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Chapter 4

Management of Audio Visual Materials with

Special Reference to their Preservation

Management is an extremely important organizational activity. It is the job of a manager

to design, create and maintain conducive environment so that personnel working in

groups are able to perform effectively and efficiently to achieve selected group goals. A

manager operates in an environment affected by internal and external factors. According

to ALA glossary of library and information science, “Management may be defined as

the process of coordinating the total resource of an organization towards the

accomplishment of the desired goals of that organization through the execution of a

group of interrelated functions such as planning, organizing, staffing, directing and

controlling.

AV materials exist in great variety. These vary in size, goals, structural pattern,

complexity and such other characteristics. From the management point of view, these

may require variation in management style, employee’s aptitude, organizational

structure, environment etc. that needs innovation of the manager. New technologies

have become available as a means to improve library services and operations. A large

number of information services and products in variety of formats are available

commercially, used by the TV Centres which are to be accommodated in TV libraries.

The main concern is to find out how libraries can adopt themselves to the new

environment so as to fully support the nation in achieving the goals. Many of the

problems and issues implied in the changing environment are related to management. In

the present context, application of management techniques has acquired added

significance. AV libraries are costly ventures. Cost must be justified by providing

effective and efficient services through efficient and effective management.

Planning is considered as the basic managerial function. According to Koontz and

O’Donnell (1980), “Planning is deciding in advance what to do, how to do it, when to

32

do it and who is to do it.” Thus it involves selecting from among alternative future

course of action for the organization as a whole and for an AV library section in

particular. It provides rational approach to managerial activities.

An AV library operates in a complex, dynamic, ever-changing and uncertain

environment. An AV library of TV media organization has to take care of broadcasting

the programmes of education, information and entertainment for the greater interest of

the masses. An AV media library is a growing organization and with passage of time,

the libraries grow into large and complex organizations.

In view of the above, proper planning becomes essential. It is one of the most important

and crucial function of management.

Before actual planning, one should become aware of opportunities/problems in the light

of existing situation and future possibilities. AV library being a service organization,

one should attempt to understand the present strength and weaknesses of the library in

the light of where it stands. In the light of knowledge about the above, a planner should

examine possible future opportunities/problems, how uncertainties are to be solved and

what is expected to be accomplished. Success of actual planning would to a large extent

depend upon realistic diagnosis of the problem situation.

Koontz and O’Donnell (1980) have laid down the following steps in planning:

1. Identification of planning objectives.

2. Establishment of planning premises.

3. Search for an examination of alternative course of action.

4. Evaluation of alternative courses of action.

5. Selection of course or courses of action.

6. Formulation of derivative plans.

7. Numberizing plan by budgeting.

Planning is considered a crucial element towards the success of any enterprise. It helps

to combat the uncertainties of the future and environmental changes. It provides

directions for carrying out day to day operations of a library.

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4.1 Organization of AV Materials

The organization of AV materials in TV media libraries is a crucial task. AV materials

have been organized by TV media libraries since the establishment of TV network.

Selection of AV materials depends on the philosophy of the TV Channel and

prospective demand for patrons as well as users.

Users of TV libraries

Mostly the programme producers, journalists concerned, news correspondence, news

editors and the staff attached with programme production like video editor, transmission

executives, scenic designers, graphic artists, cameramen, news correspondents etc are

the bonafied users of TV libraries. Besides them the out side producers, advertising

agencies, parent authorities are the users of TV libraries.

The types of users may vary as per the nature of the media houses, whether it is local,

regional, national or international. Moreover, most of the media houses are of specific

broadcaster. Some are news broadcasters and others are musical, entertain mental,

educational, on sports, cinema, spirituality, cartoons, comedies, adventures, etc.

Depending upon the type of programme they aired, the users may vary in using AV

materials from each type of media libraries. The users from inter media houses may

also use each other’s libraries. As for example, the 24 Hrs North East Satellite Channel

(NESC) since 27-12-2000, has been telecasting the programme of entire North Eastern

Region. This NESC has been running from the Programme Production

Centre(NE):Doordarshan, Guwahati. So the library of this channel has been using the

AV materials of all the twelve kendras’ libraries of the NE region. In such case, the

NESC library is operating for all the users of all participating libraries of the kendras

and vice versa.

4.1.1 Organization of Technical Services of Audio Visual Materials

Acquisition

Doordarshan central purchase and store (CP&S): Doordarshan libraries unlike other

libraries are peculiar in acquiring its holdings i.e. the video tapes and other AV

materials. Because it is a corporation based organization, and the nature of work and

services are under certain rules and regulation.

34

The blank tapes are centrally purchased by CP&S, New Delhi which is an integrated

part of Doordarshan. The CP&S is responsible for purchasing and distributing the video

tapes to all the kendras. The tapes are received by engineering store section that

maintains some basic records. The libraries acquire the tapes from engineering store

section of the concerned kendra on requirement of the producers. When new tapes are

required, library incharge put requisition slip (Appendix-2) mentioning details about the

number of tapes required, types of tapes, purpose of requirement, etc. and then the store

keeper with due recommendation of store in charge (Engineer) issues the required

number of tapes to the library in-charge.

These tapes are given the tape numbers. Generally some stickers remain inside the new

tapes which are pasted on the tape for writing the tape no. On the other hand, the tape

jacket (cover/box) have one pocket inside of which a label containing company name,

duration of tape etc. is available and the reverse side is completely blank. According to

our normal practice, this label is pulled out and the tape number is written on the reverse

side of the label and fix it again on the pocket exposing the tape number upside so that

the tape number can be seen from a near distance. So the tape numbers are written in

three places, on the tape, on front side of the jacket and on the spine of the jacket.

Although the new small size tapes don’t allow to write on the spine due to its

compactness.

The tape numbers (or so called accession numbers) are preceded by some other

information regarding types of tapes, name of the kendras, duration of the tape, etc. As

for example, a tape no “DDK/GHY/ BETA/60/200” where DDK stands for Doordrahan

Kendra, GHY stands for Guwahati, BETA stands for Betacam tape format, 60 stands for

60 minutes duration and 200 is the serial no of the tape. Likewise, DDK/SHG/D

9/64/100 refers to Doordarshan Kendra: Shillong, D 9 is a tape format, 64 minutes

duration and 100 is the tape serial number.

The system of writing tape numbers may differ from one kendra to other for different

library professionals’ own system of writing, however the necessary information must

be revealed in the number. The tapes are recorded in the Accession register. The pages

of the Accession register for blank video tapes, received from engineering stores,

contain the following information as shown in the model page below :

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Accession Register for Video tapes

( To be maintained by VTR librarian )

Acc.

No

Dt. Of

receipt

from the

eng.

Store

Sec to

which

allotted

Whether declared

unserviceable

(also quote file

no containing

sanction of the

competent

authority

Initial of

VTR

librarian

Initial of

PEX /

producer

Remarks

Commissioned programmes : Commissioning of programmes is a policy by which it

is intended to supplement the in-house programme production efforts, bringing variety

in programming in a transparent and fair manner and developing excellence in

television production. These commissioned programme tapes are the massive addition

to the Doordarshan libraries which has experienced a major collection of tapes after

every two three years.

Direct purchase : The private satellite TV channels acquire blank tapes from the

market. Some approved vendors also supply the tapes regularly on demand. Then the

librarians put accession numbers according to the style of that particular channel.

Physical arrangement

The whole idea of a system of classification or indexing is to enable to retrieve a

particular AV document containing relevant information with accuracy and instantly,

despite variation of the medium. Obviously the larger the collection, the greater the

need for detailed classification.

Unfortunately, the DDK libraries are not in a position to follow any existing

classification scheme due to some particular problems posed in front of the library

professionals.

The random sampling survey shows that the libraries have an alphabetico numeric

system of indexing. New acquisitions are added to each of the alphabetic groups and

36

arrangement of the tapes also is made accordingly in the respective shelves. This is

found to be a system in compliance with the accessioning system by type of the AV

materials not exactly in a classified way according to the content contained in the

respective tapes.

The main problem is that the same tape may contain many items (programmes). One

tape of 60 minute duration may be filled with 15 minutes of musical programmes, 15

minutes of agricultural programme and so on. So it is very difficult to put a class

number to each tape except the archived tapes.

Documentation

The DDK libraries have never maintained manual catalogues. The computerization has

been started in some libraries from the recent past. The most important task in

computerization of a media library is documentation i.e. creation of bibliographical

database. This provides for the principal interface between the users of a library and its

collection. The purpose of documentation is to make possible to the users, use of

collection without going to the materials on the shelves sequentially each time a

document is needed out of the collection. This means that adequate details about an

individual document must be given in the database with the provision of search from as

many segments and angles as possible. This is done in order to provide a wide range of

access points to a user or a library staff whosoever intends to refer to a particular

document. A database is a collection of files of data of interest in a given library. For

each document in a library, a record is maintained which contains descriptive data of

sufficient specificity to characterize the document so that the existence of the document

as well as its location in the library may be determined. The bibliographical database

can be created by using “ARCLIB” software (described in Chapter 6).

Storage material and arrangement

Storage materials are obviously the most important aspect for preservation of

documentary wealth. There are various methods, traditional and modern, for storage of

AV materials and microforms.

In early times, wood was the material in making of the shelves. The obvious reason

behind selecting wood for the purpose was its availability in abundance in every part of

37

the world, ease in framing and setting them in desired form and low cost. But today it

has been abandoned because of following shortcomings and unsuitability for

preservation of AV materials.

1. Its hygroscopicity causes dwelling and distorting in humid climate.

2. Its combustibility.

3. Frequent attack by termites and wood borer.

4. Sagging character of shelves, and

5. Shelter place for various insects.

As a result, metal rose as dominant material for shelving in archives and libraries. At

present all the DDK libraries are fitted with sideways movement compactor shelving.

The metal racks in this system move on the metal rails fitted on the floor of the libraries.

The compactor shelving is economical in space saving. It ensures effective protection of

the documentary wealth against dust and sunlight. Again It is feasible to convert the

stack area into a variable security area because it is possible to incorporate a locking

system.

The arrangement of tapes is also a vital point. As the libraries have several thousands of

different types of tapes, they must be arranged in a proper way. The tapes are arranged

serially according to the accession number under respective type of materials.

The tapes are arranged upright in the compactor shelves keeping the spine labels

exposed to the outside, as such that the tape number can be visible clearly from a near

distance.

Photograph 4.1.1(A) : Wooden Racks

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Photograph 4.1.1(B) : Compactor Shelves

Circulation

Circulation is concerned with the supply of the library materials to the users, to receive

it back in the library and also to maintain statistics related with the use. In the

computerized library, there are only two files required to be maintained for the system,

borrower’s and item’s file. All relevant details about the borrowers and the documents

are mounted on the computer and are modified while issuing or returning the

documents. This is done by bar coding device. Barcodes are placed on all documents as

well as the identity cards of the users and a barcode reader is placed on the circulation

desk. The particulars regarding the document and the borrower are downloaded and sent

to the central processing unit of the computer where the record is kept in the electronic

form. The record is updated at the time of return of the document. However, some

information are retained as it is useful for preparation of utilization report and other

related activities.

In manual system, the users have to submit requisition slips for his/her requirement of

blank tapes to the librarian. In the requisition slip, they mention the purposes of tapes to

be borrowed from the library and the requisition slip must be countersigned by in-

charge programme officer of the library. Then the librarian issued the required tapes to

the user concerned. Only a register is maintained to keep records of charging and

discharging service. The page of issue and return register is attached ( Appendix-3).

After recording or transferring or editing in the tape, it is deposited in the library. The

final tape is always accompanied with a dope sheet (Appendix-4) which is a sheet of

detailed information of the tape content. Tape no, programme title, name of

39

producer/director, all other crew members, tape reading, duration etc. are recorded in

the dope sheet.

The regular issue and return for daily transmission is done according to the cue-sheet

(Appendix-5). The cue sheet is a list of programmes to be telecast against time schedule,

which is prepared by programme section and is sent to the library. The librarian finds all

the programmed tapes in order and deposited to the Duty room/Earth station of the

concerned kendra for transmission. After transmission the tapes are returned to the

library.

4.2 Preservation of Audio Visual Materials

Preservation is the process of keeping an object safe from harm or loss, damage,

destruction or decay and maintaining it in a reasonably sound condition for present and

future use. The IFLA principles for the preservation and conservation of library

materials, defines “ preservation includes all the managerial and financial considerations

including storage and accommodation provisions, staffing levels, policies, techniques

and methods involved in preserving library and archive materials and the information

contained in them.” Thus the preservation is the adoption of appropriate prophylactic

and prospective measures to maintain the specimen in as good a condition as possible

and to prolong its life to whatever extent possible.

Feather (2004) explains preservation as something that has got something to do with the

means by which the documentary heritage is handed down to future generations, while

being made available to current users, past, present and future are the keywords of

preservation. Whatever was documented in the past is what present users are benefiting

from today, and it is the role of today’s users to safe guard the heritage for the future

generations to enjoy. Therefore, there should be a means, a tangible medium that is, to

document the information one is intending to preserve.

Preservation has the value to society over and above the value of the content that is

preserved. It is important to articulate this value in order to argue compellingly for the

creation of public policies and economic models that adequately support preservation of

culturally significant content

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The medium is what complicates the preservation of cultural heritage today. While the

principle and intention of documentary preservation remains purposeful, the type of

information career that can withstand the test of time and technological shifts without

limiting the user access has become a major issue in audio visual preservation. Although

there is no promise that guarantees everything can be preserved for life, the librarian or

archivist is left with no other choice but to put his foot down and try to put an end to the

document format dilemma.

It is instinctive among media custodians the desire and keep everything in their

collection for the sake of the future generations to come. What is in fact being

safeguarded here is not the media carrier peruse, but the information contained in these

media. Protection of the intangible heritage is always the advocacy of preservation.

Despite the looming reality that it is impossible to preserve everything forever, it does

not follow however, that custodians and archivists cannot do anything about it. What is

achievable can be done. At this point, the gathering of the AV collection in one place

and putting them in storage to extend the collection’s life line is already an act of

preservation. Edmondson (2002) defined AV preservation as the “totality of things

necessary to ensure the permanent accessibility, with minimum loss of quality, of the

visual or sonic content or other essential attributes of the work concerned.” Archivists

are all up and arms in ensuring that there is minimum loss of value in the documentary

heritage as it is being cared for, since permanent accessibility is the major point of

preservation. If the carrier is decayed and inoperable, there will be no other way then to

get to its content, therefore no cultural transmission will ever occur. Preservation adds

significance to the archival value of the object, this being the bearer of historical

evidence (Smith, 1998).

4.2.1 Magnetic Media

Magnetic media was first used in recording sound in 1935; it is in later stage used to

record images. All the materials are synthetic substances; life span is relatively short.

Environment like smoke and pollution, heat, sunlight, other magnetic fields, fluctuation

of temperature, high humidity and constant use contribute to deterioration. Extensive

use or poor conditions can severely shorten the life of a tape.

41

Fifty years ago, the magnetic tape era would have given a posterity promise to the

broadcasting world. With the wear and tear capacity of this medium at that time,

magnetic tapes seemingly offered greater advantages over film stocks in terms of

malleability and cost. For these reasons, a video tape was seen as “a medium for long

term historical record keeping” (Martin, 2005). However as with most information

carriers, this medium is not exempt from the elements of the ever changing shifts in

media technology. Its physical benefits might have foretold its life expectancy as the

ideal carrier, but not really.

Technology continues to contribute to quality and longevity of tape, and to change

recording devices and formats, producing products that cast better, as well as new

products with unknown shelf life. Equipment also changes along with the tape medium,

unless which particular tape may be in good condition but cannot be played for lack of

the right equipment.

Bogart (1995) has described in detail the different aspects relating to the magnetic tapes

storage and handling and he elaborated the concepts on magnetic media compared to

paper and film, physiology of magnetic media, audiovisual recording procedure in

magnetic media, tape cost and longevity, practical life expectancy, care and handling of

magnetic tapes, frequent access, transportation of magnetic tape, storage condition and

standards, temperature and relative humidity, dust and debris, corrosive gases, removal

of magnetic tapes from archival storage, refreshing of tapes etc. as below.

Magnetic media compared to paper and film

The magnetic tapes as the information storage media are not as stable as film or paper.

Properly cared for, film and non acidic paper can last for centuries, whereas magnetic

tapes will only last a few decades. Use of magnetic media for storage is further

confounded by the prevalence of several formats ( e.g. U-matic, VHS, S-VHS, 8mm and

Betacam for video ), media types ( iron oxide, chromium dioxide, barium ferrite, metal

particulate and metal evaporated ) and by rapid advances in metal technology. On the

other hand, books have virtually maintained the same format for centuries, have almost

exclusively used ink on paper as the information storage medium and require no special

technology to access the recorded information. Likewise newer microfilm, microfiche

42

and movie film are known for their stability when kept in proper environments and

viewing formats have not changed significantly over the years.

The physiology of magnetic media

The magnetic audio and video tapes have a similar physical structure, they consist of a

thin layer capable of recording a magnetic signal supported by a thicker film backing.

The magnetic layer or top coat, consists of a magnetic pigment suspended within a

polymer binder. As its name implies, the binder holds the magnetic particles together

and to the tape backing. The structure of the top coat of a magnetic tape is similar to the

structure of Jell-o that contains fruit- the pigment (fruit) is suspended in and held

together by the binder (Jell-o). the top coat, or magnetic layer, is responsible for

recording and storing the magnetic signals written to it.

Figure 4.2.1(A): Tape Reel showing the principal components

(Source: Magnetic tape storage and handling: A guide for libraries and archives by Dr.

John W.C.Van Bogart (1995), National Media Laboratory)

The tape is wound around the hub of a tape reel forming a tape pack. The tape pack is

protected from damage and disruption by flanges on the reel. The binder also has the

function of providing a smooth surface to facilitate transportation of the tape through

the recording system during the record and playback processes. Without the binder, the

tape surface would be very rough, like sand paper. Other components are added to the

43

binder to help transport the tape and facilitate information playback. A lubricant is

added to the binder to reduce friction, which reduces the tension needed to transport the

tape through the recorder and also reduces tape wear. A head cleaning agent is added to

the binder to reduce the occurrence of the head clogs that result in dropouts. Carbon

black is also added to reduce static charges, which attract debris to the tape.

The backing film, or substrate, is needed to support the magnetic recording layer, which

is too thin and weak to be a standalone film layer. In some tape systems, a back coat is

applied to the back side of the tape substrate layer. A back coat reduces tape friction,

dissipates static charge and reduces tape distortion by providing a more uniform tape

pack wind on the tape reel.

Figure 4.2.1(B): Cross Section of Magnetic Tape

(Source: Magnetic tape storage and handling: A guide for libraries and archives by Dr.

John W.C.Van Bogart (1995), National Media Laboratory)

Magnetic particles are held together with a binder coated on a film substrate. Lubricants

and other agents (not shown in this figure) may also be included in the top coat layer. A

back coat may also be added to control friction and static charges. The structure of the

top coat is analogous to that of Jell-o filled with grapes where the grapes represented the

magnetic particles and the Jell-o represented the binder.

44

Thus the constituent elements of these magnetic tapes are as follows:

• Polyester base ( Polyethylene terephtalate )

• Agglomerant binder ( polyurethane )

• Metallic oxide particles ( chrome dioxide, iron oxide, etc.), that are integrated

within the agglomerant binder ( high quality tapes additionally incorporate an

anti-mycotic substance to prevent fungus from spreading ); and

• The carbon inferior layer that protects the tape from scratches, and reduces

mechanical friction.

Each of these elements can deteriorates differently. The layers of the tape may

deteriorate or flake off; friction from deteriorating tape can result in failure of the tape

to feed through the machine. The playing equipment can also cause problems, such as

build up on the head, resulting in signal failure.

Audiovisual recording procedures in magnetic media

The analog recording and digital recording are the two recording system in magnetic

media. The analog recording system is used for groove records and magnetic cassettes,

the sound is transformed in “parallel” (e.g. in vinyl records, a needle picks up the

mechanical vibrations produced by the relief of a groove, and the signal is then

transformed into an electrical impulse), or in the aligning of particles in magnetic tapes.

This procedure has the advantage of being inexpensive, although it is very sensitive to

variations between the reading mechanisms (needles or magnetic readers) and the media

in which the information is recorded, since there is physical contact between the two.

The susceptibility of the recording to loss as a result of dimensional changes in the

backing is dependent on recording format. Video tape, which uses a helical scan

recording format is more sensitive to disproportionate dimensional changes in the

backing than analog audio tape, which uses longitudinal recording.

Tracks are recorded diagonally on a helical scan tape at small scan angles. When the

dimensions of the backing change disproportionately, the track angle will change for a

helical scan recording. The scan angle for the record/playback head is fixed. If the angle

that the recorded tracks make to the edge of the tape don’t correspond with the scan

angle of the head, mistracking and information loss can occur.

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Figure 4.2.1(C): Types of Mistracking for Helical Scan Recording

(Source: Magnetic tape storage and handling: A guide for libraries and archives by Dr.

John W.C.Van Bogart (1995), National Media Laboratory)

Trapezoidal error occurs when the angle of the recorded track does not agree with the

scan angle of the playback head. Curvature error occurs when the tape has deformed

nonlinearly. The playback signal corresponds to that for a single helical scan.

Distortion of a helical scan video tape can result in two types of mistracking-trapezoidal

and curvature. In trapezoidal mistracking the tracks remain linear, but the track angle

changes so that the playback head, which is always at a fixed angle to the tape, cannot

follow them. Curvature mistracking can be a more serious type of deformation where

the recorded tracks become curved as a result of non linear deformation of the tape

backing. Mistracking will result in a video image where some or all of the screen is

snowy or distorted. For example, in the case of trapezoidal mistracking, the upper

portion of the TV screen may appear normal, whereas the lower portion of the screen

may be all static. The appearance on the screen will be similar to the playback of a good

tape where the tracking adjustment control has been purposely misadjusted.

In the longitudinal tape system, the heads are arranged along a fixed head stack-one

head per track and the other tracks will always remain parallel to the edge of the tape.

Mistracking is not as great a problem in longitudinal recording for this reason.

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Figure 4.2.1(D): Longitudinal Recording

(Source: Magnetic tape storage and handling: A guide for libraries and archives by Dr.

John W.C.Van Bogart (1995), National Media Laboratory)

A moving tape passes across a stationary record head. The recorded tracks are parallel

to the edge of the tape and run the full length of the tape. A nine-track tape is shown in

the above figure.

Distortion of a longitudinal audio recording tape will appear as a temporary muffling,

change in pitch, or loss of the audio track. Distortion of the tape backing can impart a

slight curve to the normally linear type. When the distorted portion of the tape passes

over the playback head, the recorded tracks can move out of alignment with the head

gap, causing a temporary reduction in sound volume and quality.

In digital recording, the sound, video image or the data is transformed into binary codes

which are transformed into electrical impulses. The digital recording system is,

according to J. Wheeler (1983), the best form of archive, because digital recording

procedures provide a solution to the two main conservation problems of the medium.

Firstly, it allows the quantification of any material deterioration, as the system can

measure accurately the errors that are eventually produced in the recording, and there

are secure procedures to correct them, even when a great amount of data has been

damaged. Secondly, it makes it possible to produce an exact duplication of the original.

47

Magnetic media and causes of deterioration

The main problem concerning with the magnetic tapes is agglomerate stability, that is

the stability of the component maintaining the joint between the magnetic particles and

the plastic support. When the tapes are exposed to humid conditions and unfavorable

temperature, the different layers of which they are composed contract and expand.

These variations sometimes cause irreparable damage to the magnetic surface: this can

break the agglomerate and cause the metallic particles to detach from their plastic base.

This phenomenon is described in the specialist literature as “flaking off”.

The magnetic films are generally made from organic materials and therefore, are prone

to suffer degradation. The old black and white films present four or five layers of

different chemical compositions; colour films are also composed of a series of layers

that are only a few microns thick. In both kind of films, the main component is gelatin,

which is a particularly sensitive product due to its easy reaction to water, while also a

good medium for growing fungus and germs.

E. Cuddihi (1988) described how inadequate environmental conditions (mainly

humidity and temperature) promote deterioration of the adhesive through its main

component, the polyurethane, hydrolyzing that is becoming sticky and impossible to

read. This chemical effect is commonly known as the “sticky shed syndrome”.

Reilly (1993) pointed out that the materials made of cellulose suffer from the same

deterioration problems, although environmental conditions are the important factors.

The velocity of deterioration very much depends on temperature conditions and

humidity, due to the chemical reactions that they promote.

Inappropriate storage in excessively humid conditions creates additional problems. It

favors the spread of fungus, which can also severely damage the agglomerant: it can

cause the destruction of the document medium and the contamination of other magnetic

document via the liberation of spores.

The deterioration mechanisms of nitrate and acetate films derive from an autocatalytic

type of reaction. This means that the accumulated chemical degradation products

generate more yet deterioration, so that, once the degenerative process has been started,

48

the speed of chemical activity increases, which at the same time increases gas

emissions. In this way the deterioration process of film materials is speeded up,

sometimes in an irreversible way. To prevent the accumulation of gaseous products

from chemical deterioration, negatives must be removed periodically from their storage

containers, so that by using well-ventilated storage the evacuation of gaseous by-

products will be made easier.

Volkman & Schou (1986) pointed out that “the destructive processes of film are

determined by natural laws that we cannot alter. All we can do is slow down

significantly the destruction process until it is possible to transfer its contents to a more

stable environment”. This assertion has special relevance to the nitrate medium, a

material that has been widely used in negative manufacturing, transparencies, cartoons,

microfilms and the like. Unfortunately, cellulose nitrate and acetate are very unstable

materials and the products of degradation can severely harm, and even destroy

photographic collections, what is more, they can be potentially harmful for those who

work with them.

Moreover the magnetic media may be deteriorated by

• Edge damage, which is caused by improper winding and a poor tape pack

results. The tape’s control track (a signal that tells the VTR to pull the tape

through the machine) is on the edge of the tape. If the control track is damaged,

the tape does not play.

• Creased tape (Clinching) can also occur from an improper tape pack.

• Drop outs can be caused by dirt or other debris coming in contact with the tape

as it crosses the VTR head. The debris can become embedded on the tape.

• Stretched tape occurs when a tape is left in pause for more than 5 seconds.

Magnetic media and their life expectancy

The magnetic media life expectancy (LE) information is largely undocumented and a

standard method for determining magnetic media life time has yet to be established. The

LE of magnetic media can be ten to thirty years near normal climatic conditions, it is

important to understand that environmental storage conditions can optimize or seriously

compromise the lifespan of magnetic tapes. Earlier stability studies have attempted to

49

chart the impact of storage conditions on the longevity of the magnetic media. The

lifespan of magnetic media was estimated based upon the effect of temperature and

relative humidity (RH) on the stability of the polymer binder as reflected by its degree

of hydrolytic deterioration. An early study recommended storage environments based

on the level of binder hydrolysis. Temperature and RH recommendations were

determined to meet requirements for both tape storage and use (Bertram, and Cuddihy,

1982, p. 993-999). The recommendations were based on the relationship between

acceptable degrees of hydrolysis and operational problems when tapes were played.

Later publications provided insights into the lifespan of tapes. Based on the given end of

life criterion, LE were quantified based upon data obtained through accelerated aging. It

was recognized that polyester polyurethane degrades through hydrolysis. Higher

humidity promotes the breakage of polyester linkage by the reaction with water.

Degradation byproducts such as organic acids are believed to accelerate binder

hydrolysis. The model makes life span predictions possible and establishes a

relationship between storage conditions and LE values. Estimates for tape LE may vary

from less than ten years to several decades, depending on temperature and RH levels.

As a general rule, lower temperature and drier conditions lead to longer life span. It

should be noted that the link between chemical stability and climatic condition is not

specific to magnetic tape alone but applies to a wide range of organic materials, such as

photographic film.

Tape costs and longevity

Some people assess storage media solely in terms of media cost. This view assumes that

the sound, images or information stored on the media have no intrinsic value. However,

a storage medium should be evaluated in terms of the cost of losing the recorded

information in the event that the storage medium degrades irreversibly.

The value of the tape must be equated with the cost of preserving the data. When the

cost of losing the information is considered, it may be economically justified to invest

more in a medium / system of proven reliability. It may also warrant the cost of making

and keeping replicated copies of original data and stockpiling systems to play back the

data at future times.

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When purchasing media of a specific format, some archivists are required to deal with a

procurement bidding process. In most cases, the archivists will end up with the lowest

bidder’s media, which may not be the best media. Tape manufacturers’ products differ

in coating thickness, magnetic particle stability and durability. Procurement

specifications should exclude the poorer media. The vendor should be asked for

experimental proof of the stability of the media if the tape is to be used for archival

storage.

Practical life expectancies

The archivists who accustomed to storing paper and microfilm may be annoyed by the

relatively short life expectancies of magnetic AV materials. Some gold plated / glass

substrate digital optical disc technologies promise 100 years life times. However, a 100

year life expectancy is irrelevant when the system technology may be in use for not

more than 10 – 20 years or less.

Audio and video recording technologies are advancing at a much faster rate than

printing and microfilming technologies. We are fortunate if a recording technology

stays current for more than twenty years. In the case of a magnetic recording media with

a fifty year LE, the media would undoubtedly outlive the recording system technology.

To truly achieve a fifty year archival life, recording systems, sufficient spare parts and

technical manuals would need to be archived along with the recorded media.

In the case of audio and video archives, transcription is inevitable. Rather than trying to

preserve old, outdated recording formats and technologies, it may be more practical to

transcribe on a regular basis- every 10 to 20 years or even more frequently. The old

copy could be preserved until the new copy is transcribed to the next generation of

recording system. In this style, at least two copies of the material are always in

existence.

Care and handling of magnetic tape

The magnetic tapes should be handled with care, keep them clean and apply common

sense as below:

• Use and store magnetic tape reels and cassettes in a clean environment.

51

• Avoid contamination of the tapes by dirt, fingerprints, food, cigarette smoke and

ash and airborne pollutants.

• Take care not to drop tapes or cartridges.

• Keep tapes out of strong sunlight and avoid contact with water.

• Don’t store tapes on radiators, window sills, televisions, electronic equipments

or machinery.

• When the tapes are not in use, they should be placed back on the storage shelf

and stored on end. They should not be allowed to lay flat for extended periods of

time.

Magnetic tapes do require some unique care and handling precautions. Because they are

magnetic form of storage, exposure to strong magnetic field must be avoided to prevent

information loss. This is generally not a problem, unless the materials need to be

transported from here and there.

Frequent access

Tapes which are frequently accessed may have a reduced life expectancy due to wear

and tear. The life of the media may not be determined by data error rates, but by the life

of the media housing. In one instance, the life of a tape was limited by failure of the

cassette door, not because of any fault of the tape media. How many insert and eject

cycles will the media be required to handle – this may limit the life of the cassette.

The more tapes are handled, the more these are contaminated with fingerprints and

debris. It is also exposed to less than ideal conditions, especially if the materials are

removed from the building in which they are normally stored.

Every time a tape/cassette is loaded into a recorder, mechanism pulls tape from the

cassette. This mechanism can damage the tape if the guide pins are not properly aligned.

Debris on loading mechanism can scratch the surface of the tape. Also, when a tape is

removed from a recorder, the tape must properly retract into the cassette, otherwise it

will be damaged when the cassette doors close and the tape/cassette is ejected from the

recorder.

52

Because of the potential damage to the tape, it is important that the tapes be inserted and

ejected at areas of the tape that contain no recorded information. A tape should never be

ejected in the middle of an important recording.

Transportation of magnetic tape

Care must be exercised to ensure that tape collections are not harmed when they are

transported. When magnetic media are transported temperature should not exceed 110ºF

(43ºC). Collections should be transported when outdoor temperature are moderate, if

possible. Properly wound tape reels can survive greater variations in temperature and

humidity without permanent damage than can poorly wound tape packs.

Tapes/cassettes should be transported in the same orientation as they are stored - on

edge with the weight of the tape pack being supported by the reel hub. Tapes which are

transported in the flat position are particularly subject to damage from dropping and

other forms of shock. This is especially true of tapes that experience large changes in

temperature during shifting which are poorly wound.

Media should be protected from damage due to shock by packing them in materials that

will absorb shock (special packages, bubble wrap) using special labeling, and

transporting them in appropriate vehicles. Shock absorbing packaging will often have

the added advantage of providing insulation that helps protect the media from large

swings in temperature and humidity.

Exposure to strong magnetic fields must also be avoided to prevent information loss.

Some of the detectors used to screen luggage at security points have been known to

partially erase tapes. Walk through metal detectors and x-ray scanners do not pose a

threat to recorded information. Some hand held metal detectors can cause problems

since they use strong magnetic fields.

Storage conditions and standards

Storing magnetic tapes in a clean, controlled environment is the most important

precaution for the extended life of this media. High temperature, high humidity and the

presence of dust and corrosive elements in the environment affect the components that

constitute magnetic tape and can result in loss of readable data through decreased

53

magnetic capability and deterioration of the binder or backing of the tape. Too low

temperatures should also be avoided. In some cases, temperatures lower than 32º F

(0ºC) may actually harm the media and shorten, rather than extend, life expectancies by

risking exudation of the lubricant from the binder, which may clog heads. Rapid

temperature changes are also undesirable as they introduce stresses in the wound tape

pack. Tapes those are to be played in an environment different from the storage

environment should be allowed to acclimate to the new temperature.

Temperature and relative humidity

The common recommendation is to store the tapes in cool, dry place. In fact, binder

hydrolysis is dependent on moisture content of the tape and lower humidity results in

lower rates of hydrolysis. Moreover, the reaction proceeds more slowly at lower

temperature. The latter is also true for the magnetic pigments- they will degrade more

slowly at lower temperature. Finally, to reduce unnecessary stresses on the wound tape

that could result in deformation of the backing, a limited variation in temperature and

humidity is recommended.

Storage at high temperature (>74º F; >23º C) increases tape pack tightness. This results

in distortion of the tape backing and an increase in permanent dropouts as wound- in

debris is forced into the tape magnetic layer. Many layers of tape before and after the

debris can be affected by impressions of the debris. Layer to layer adhesion known as

tape backing, also can result after long term storage at elevated temperature.

Storage at high humidity (>70% RH) results in increased degradation of the binder as a

result of the higher moisture content of the tape pack. High humidity will also cause

increased tape pack stresses as the tape absorbs moisture from the air and expands,

causing distortion of the tape backing and an increase in permanent dropouts.

Fungal growth is also possible at high humidity and temperature. Moulds can live off

the binder polymer and added components. This is yet another cause of binder break

down in high humidity. Hairy growths at the edges of the tapes are a sign of mould. The

spores those are produced on this fuzz can get onto the tape surface and cause many

dropouts.

54

Changes in both temperature and humidity can also cause mistracking problems on

helical recording (Refer fig. 4.2.1(C) above). Substrates will expand or shrink with

changing temperature and humidity just as metals do in heat or cold. The substrate films

are not completely balanced in their reaction to these changes in temperature and

humidity. In other words, they stretch and shrink differently in length and width

directions. This causes a change in the angle of the recorded helical scan tracks. Most of

these changes are recoverable by returning to a temperature and humidity close to the

one at which the tape was recorded. However, heat can also cause premature aging of

the substrate in the form of non recoverable shrinking and stretching.

Variations in temperature and humidity

The temperature and humidity in a tape storage facility are generally set to specific

values or set points, and frequently varied or adjusted. This does not mean that the

temperature and humidity in the facility are invariant. Changes in the outdoor

temperature and humidity will cause the temperature in the tape storage facility to vary

slightly.

If the outdoor temperature is higher than the set point temperature in the facility, the

actual temperature in the facility will be slightly higher than the set point. If the outdoor

temperature is lower than the set temperature, the actual facility temperature will be

lower than the set point. The variations in temperature experienced will be larger at

larger distances from the thermostat in the facility. The same logic applies to the

humidity level in the facility. Larger discrepancies in the set point and the actual

temperature will be observed if one of the walls of the facility is an exterior wall, or if

the heating/cooling capacity of the environmental controller is less than that required to

properly control the tape archive.

The set point in a tape archive may be constant, but the archive will still experience

same degree of daily and seasonal variations in temperature and humidity. A tape

archivist must have knowledge of the set points in the archive as well as the variations

in temperature and humidity to ensure that the archive complies with recommended

storage conditions.

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Variations in temperature and humidity can cause tape problems. Tape packs are wound

under a considerable amount of tension. This is necessary to maintain the shape of the

tape pack. A reel of tape may be permanently damaged if the tape pack tension is too

high or too low. If the tension is too high, the tape backing can stretch. If the tension

gets too low, tape layers can slip past each other, resulting in pack slip, clinching or

popped strands on playback. Relaxation of the tape backing can also occur if the tape

pack tension is not properly maintained. Relaxation, stretching and deformation of the

tape backing can cause mistracking of a video tape or sound distortion on an audio

tape. Every time a tape pack is heated or cooled, the tape pack tension will increase or

decrease respectively. The best way to reduce the degree of tape backing distortion is to

store magnetic media in an environment that does not vary much in temperature or

humidity.

Figure 4.2.1(E): Bad Tape Wind

(Source: Magnetic tape storage and handling: A guide for libraries and archives by Dr.

John W.C.Van Bogart (1995), National Media Laboratory)

This figure shows schematic examples of popped strands, pack slip, and a flange pack.

The illustrations show a cross-section slice of the tape pack through the hub.

Dust and debris

Dust, smoke particles and tape debris present in the environment can get wound into the

tape pack as the tape is played, resulting in dropouts when the tape is subsequently

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played. The lost signal is generally greater than expected from the size of the particle.

The record and read heads must maintain very close contact with the tape. A particle of

dust on the tape causes the head to ride up over the particle and lose contact with the

tape. The figure below shows the various debris compared to the normal head to tape

spacing.

Figure 4.2.1(F): Debris Perspective on High Density Digital Recording Tape

(Source: Magnetic tape storage and handling: A guide for libraries and archives by Dr.

John W.C.Van Bogart (1995), National Media Laboratory)

Corrosive gases

The magnetic tapes are susceptible to corrosive gases in the environment. Exposure to

very low levels of corrosive gases, has been known to cause corrosion on bare metal

particle (MP) and metal evaporated (ME) tapes. In general, these tapes are contained in

cassettes and the cassette shells have been shown to be effective armour against

pollutants in the environment. This corrosion problem is limited to the metal based MP

and ME tapes and is not a significant factor in the deterioration of oxide tapes (Iron

oxide, chromium dioxide, barium ferrite).

If a tape archive is known to contain MP or ME based magnetic tapes and the tape

archive is situated in an environment characterized by high levels of pollutants, some

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precautions may be necessary to ensure that the level of chlorine and sulphides in the

archive are at a sufficiently low level. Air conditioning systems may require special

filters to remove pollutants if the archive is located in an urban environment.

Removal of magnetic tapes from archival storage.

The magnetic tapes cannot be immediately removed from archival storage conditions

and played on a recorder. Time must be allowed for the tapes to equilibrate to the

temperature and humidity of the recorder environment prior to playback. This allows

the stresses in the pack to equalize and the track shapes (helical scan) to return to

normal. In the case of very low temperature storage, it may be necessary to place the

tapes in an intermediate storage environment first to prevent condensation of moisture

on the tapes and reduce stresses on the tape pack that would be introduced by rapid

temperature changes.

In general, it is the width of the tape that determining how rapidly it will come to

equilibrium. A tape that is twice as wide will take four times as long to stabilize to the

new environment.

The table below indicates the amount of time that should be allowed for the tapes to

come to equilibrium after significant changes in temperature and humidity ("Heat and

moisture diffusion in magnetic tape packs", 1994, p. 237)

Table 4.2.1: Acclimation times for Magnetic media Removed from archival storage

Tape Format Time for Temperature

Acclimation

Time for Humidity

Compact Audio Cassette 1 Hour 06 Hours

¼ inch reel to reel 1 Hour 01 Day

2 inch reel to reel 16 Hours 50 Days

VHS/Beta Cassettes 2 Hours 04 Days

8 mm Video Cassette 1 Hour 02 Days

Umatic Cassette 4 Hours 08 days

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A tape that is stored at a temperature or humidity that is significantly below that of room

ambient conditions must be allowed to acclimatize prior to play back.

Refreshing of tapes

The periodic refreshing may give the tapes an useful life. Refreshing is not a standard

term in the tape recording trade which is referred to the retensioning or rerecording of

the tape, depending on the community of tape users. To avoid confusion, the term

retensioning and rerecording are preferred to refreshing.

Retensioning is normally recommended where prolonged tape pack stresses could cause

damage to the tape. Some manufacturers have recommended that tapes be unspooled

and rewound at regular intervals to redistribute tape stress and prevent tape pack slip,

clinching and tape backing deformation. Some tape user communities refer to the

process of retensioning as exercising the tape.

Recording requires that data be read from and written to the same tape periodically to

refresh the magnetic signal and prevent data loss. Transcription, the copying of one tape

to another, has also been referred to as refreshing. Transcription is the preferred term for

this process. Tapes purchased today generally utilize small diameter tape reels and high

coercivity magnetic pigments so that they often do not require retensioning or

rerecording on a periodic basis.

Refreshing should not be confused with restoration. Refreshing is a preventive

maintenance procedure. Restoration refers to the reconditioning of a damaged or

degraded tape in order to allow playback. Restoration is a repair or damage recovery

procedure

4.2.2 Digital Media

As the television and broadcast facilities are gradually changing over to digital

broadcasting, the need for digital video preservation becomes apparent. Data rates for

video are increasing dramatically as more media houses move towards broadcasting in

digital video standard definition (SD) and high definition (HD). Hence the video need to

be preserved.

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The audio visual records are always at risk. The digitization has been a solution, which

has created a new problem : Preservation of digital Audio visual content. Preservation

of digital media encompasses both preservation of materials which are created in

digitized form and never exist in analog form which are called “born digital” and the

use of recording technologies to create digital surrogates of analog materials for access

and preservation purposes. The first one ensures the longevity of electronic documents

in comparison to the second one.

The digital preservation can be described as using digital technology to preserve the

information content. The born digital and converted digital form are threatened by

technology obsolescence and physical deterioration. Moreover, the digital materials are

especially vulnerable to loss and destruction because they are stored on fragile magnetic

and optical media which deteriorate rapidly and can fail suddenly from exposure to heat,

humidity, airborne contaminants etc.

The digital preservation is termed as long term, error-free storage of digital information

with possible means for retrieval and interpretation and keeping the digital materials

alive into the future. Digitization refers to the conversion of analog material to digital

form. The digital form is a form which uses a binary numerical code to represent

variables.

The goal of digital preservation is to maintain the ability to display, retrieve and use

digital collections in the face of rapidly changing technological organizational

infrastructures and elements. In the digital era, “Preservation is the creation of digital

products worth maintaining over time” (Vinitha 2010).

Audiovisual recording on digital media

In the electronic media world, digital preservation has a great concern for the longevity

of the AV contents. The gradual obsolescence of analog magnetic media leads to the

increasing use of digital media. The digital recording can be divided into two groups :

1. The digital recordings on dedicated physical carriers like Digital Betacam,

Digital-S D9, D1, D2, D3, D5 HD, DV, HDV, Pro HD, Mini DV, D-VHS, DVD

etc.

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2. Digital recordings that exists as files on digital storage. All the advanced

equipments can record sound and moving images directly into the device’s

memory, at which point the recordings are files and have an existence that is

independent of any particular storage media.

Some certain technological procedures and workflow is required to move the recordings

into files.

Need of preservation on digital media

Due to technological revolution, digital preservation has become the important process

in information society to have the long term access of information and to keep it for

future generations for their use. Digital preservation is needed for the following reasons

(Bajpai, Hada and Singh 2010).

• To provide information about our cultural heritage and history for future

generation.

• To solve the space problem.

• Provide accessibility and flexibility to the users.

• To keep materials alive for the future generations.

• Avoid duplication of effort and expenses.

• To provide accessibility across the globe.

• To maintain the information about the historical value.

• To prevent the important document from wear and tear.

• To reduce the effects of deteriorating factors.

Strategies for digital preservation

Several strategies are adopted for digital preservation. In 2006, the OCLC (Online

Computer Library Centre) developed a four point strategy for the long term preservation

of digital objects that consisted of (Seifi and Nikam, 2010).

• Assessing the risk for loss of content posed by technology variables such as

commonly used proprietary file formats and software application.

• Evaluating the digital content objects to determine what type and degree of

format conversion or other preservation action should be applied.

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• Determining the appropriate metadata needed for each objects type and how it is

associated with the object.

• Providing access to the content.

There are more other strategies of digital preservation.

Refreshing

The copying of digital files from one storage medium to another is termed refreshing.

With the advent of new formats and technology, the older storage media become

unreliable and vulnerable. Refreshing may provide more reliable storage medium that

offer higher capacity, better access and low price. For example, data stored in several

CD’s will be fit in one DVD. Refreshing is the one means for media obsolescence and it

is not a full preservation strategy (Bajpai, Hada and Singh,2010).

Migration

Migration is a primary strategy and is the process of transfer of files periodically from

one format to another format or one generation of computer to latest generation of

computer, without loss of the original. It has been defined as “a set of organized tasks

designed to achieve the periodic transfer of digital materials from one

hardware/software configuration to another or from one generation of computer

technology to a subsequent generation”(Commission of Preservation,1996). It ensures

that the digital information re-encoded in new formats before the old format becomes

obsolete.

The aim of this process is to preserve the integrity of digital objects and materials and

retain the same for their users. In other words, we can say that, migration is the process

of converting the digital material for operation in different digital environment for their

users without loss of the original, if we want the data migrate to different environment.

In these processes, we don’t loss any data. Every time if we want to migrate data, it will

also result in the change of the format of the file. It is also a major concern to migrate

the data in newer environment (Bhatt & Kumar,2011).

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Emulation

This process refers to creating new software that performs the operations of older

hardware or software in order to reproduce its performances. Thus, not only are physical

presence and content preserved but digital objects could display original features

(layout) and functionality available with the older software. Emulation is established as

a potential strategy to assist preservation, recognizing that some electronic material that

is highly dependent on particular hardware and software will not lend itself to

migration. One of the benefits of the emulation strategy compared with migration is that

the original data need not be altered in any way. It is the emulation of the computer

environment that will change with time. This should help maintain the integrity and

“look and feel” of the material. Another advantage of implementing emulation is its

possible efficiency. Once the data is archived with appropriate metadata and software,

no other action is required apart from media refreshing until access is desired. One

emulator can also be used as a solution for several data objects requiring the same

operating environment.

Metadata

Metadata is structured information that describes, explains, locates or otherwise makes

it easier to retrieve, use or manage an information resource. Metadata is often called

data about data. It is an essential component of most of the digital preservation

strategies. Without metadata we can’t access and use digital objects and there is no

alternative of metadata.

As the digital AV archives grow, both through the increasing volume of new digital

video productions and the conversion of the analog AV record, the need for metadata

creation similarly increases. Automatic analysis of video in support of content based

retrieval will become a necessary step in managing the archives. A recent editorial by

the Director of the European Broadcasting Union Technical Department notes that

“efficient exploitation of broadcasters’ archives will increasingly depend on accurate

metadata” (Laven, 2000).

As the analog video resources are digitized and new video is produced digitally from the

outset, the video itself, once encoded as bits, can be copied without loss in quality and

63

distributed cheaply. Metadata for video are crucial when one considers the large volume

of bits within digital video representatives.

There are three types of metadata:

a) Descriptive: facilitating resource identification and exploration.

b) Administrative: supporting resource management within a collection.

c) Structural: binding together the components of more complex information

objects.

An important reason for creating metadata is to facilitate discovery of relevant

information. In addition to resource discovery, metadata can help organize electronic

resources, facilitate interoperability and legacy resource integration, provide digital

identification and support archiving and preservation.

Metadata serves the same functions in resource discovery as good cataloging does by-

• Allowing resources to be found by relevant criteria,

• Identifying resources,

• Bringing similar resources together,

• Distinguishing dissimilar resources and

• Giving location information

Transformation of television production : From analog to digital

Public television is responsible for the production, broadcast and dissemination of

programmes which form the richest audio visual source of cultural history in the United

States (Library of Congress,1997).

The National Digital Information Infrastructure Preservation Programme (NDI-IPP) of

Library of Congress, in its first set of reports, identified the challenges of preserving

digital television productions:

By nature and necessity, public broadcasting is a hodge-podge of media types and

formats. In whatever manifestations these objects previously existed, they become bits

and bytes before they reach the public eye. That is an enormous amount of digital

information to manage over time. As we move into the increasingly complex digital

world, those charged with preserving our television heritage have the opportunity to

64

develop and establish better coordinated and standardized preservation policies and

practices to ensure what television programme and related assets survive (Ide, Mac

Carx, Shepard & Weisse, 2002).

In Indian context, it is not evident that TV broadcast operations will be altered rapidly

by digital production and distribution technologies. Gradually the broadcast television

will be shifted from a manual process based on video tape, to that is almost entirely file

based. Virtually all programmes are now shot and edited digitally and completed

programmes are finalized as digital files. Television distribution and transmission will

be equally transformed, as tape based submissions to the public broadcasting service are

being replaced by digital file transfer, which leads to tapeless broadcasting and the

programmes are stored, assembled and aired as files directly from a server.

The taste of viewers also has shifted as well. The explosion of broadcasting channels,

coupled with a constantly changing array of viewing devices, have created a

fundamentally altered video environment which requires programming to be viewable

on everything from the very smallest ipod screen to giant wall size flat panels. Hence,

there is a need to turn off the analog transmitters and be broadcasting exclusively on

digital channels. The all digital television chain will be complete, from programme

producer at the start of production to the mobile viewers at the end of the line.

4.2.3 Optical Media

Optical media refers to discs that are read by laser light. This includes CD-ROMs,

DVD-ROMs and all the variations of the two formats- CD-R, CD-RW, DVD-R,

DVD+R, Blue Ray etc. Optical discs are less likely to lose their data and have a longer

shelf life around seven times longer than magnetic media. The discs are also more

durable than hard drives and are much cheaper to produce, making them great for back

ups and for transferring small amounts of data between different computers.

<www.techterms.com/definition/optical media>.

Optical discs have been a popular form of storage media due to its low cost, ease in

manufacturing and portable size. Optical storage media is flat, usually circular disc and

found between 7.6 and 30 cm in diameter, however, the generally available on most

common and standard size disc is measuring 12 cm in diameter. A typical disc is about

65

1.2 mm (0.05 inch) thick while the track pitch (distance from the centre of one track to

the centre of the next track) is typically 1.6 µm. Since 1982, optical media is still the

standard for purchased music and movie physical media. Several types of media are still

in use today.<http://www.ehow.com/about_5384975_types-optical-storage

devices.html#ixzz26vmk17xs>

In computing and optical disc recording technologies, an optical disc encodes binary

data (bits) in the form of pits (binary value of 0 or off, due to lack of reflection when

read) and lands (binary value of 1 or on, due to a reflection when read) on a special

material (often alluminium) on one of its flat surfaces. The encoding material sits atop a

thicker substrate (usually polycarbonate) which makes up the bulk of the disc and forms

a dust defocusing layer. The encoding pattern follows a continuous, spiral path covering

the entire disc surface and extending from the innermost track to the outermost track.

The data is stored on the disc with a laser or stamping machine, and can be accessed

when the data path is illuminated with a laser diode in an optical disc drive which spins

the disc at speeds of about 200 to 4000 RPM or more, depending on the drive type, disc

format and the distance of the read head from the centre of the disc (inner tracks are

read at a faster disc speed). The pits or bumps distort the reflected layer light, hence

most optical discs characteristically have an iridescent appearance created by the

grooves of the reflected layer.

The reverse side of an optical disc usually has a printed label, sometimes made of paper

but often printed or stamped onto the disc itself. This side of the disc contains the actual

data and is typically coated with a transparent material, usually lacquer. Unlike the 3 ½

inch floppy disk, most optical discs do not have an integrated protective casting and are

therefore susceptible to data transfer problems due to scratches, fingerprints and other

environmental problems.

Types of optical media <http://en.wikipedia.org/wiki/optical_disc#mw-head>.

There are three types of optical disc based on recording patterns. An optical disc is

designed to support one of the following types.

Read-only Memory (ROM) disc: This type (CD and CD-ROM) of discs are used for

the distribution of standard program and data files. These are mass-produced by

66

mechanical pressing from a master die. The information is actually stored as physical

indentations on the surface of the CD. Recently low-cost equipment has been introduced

in the market to make one-off CD-ROMs, putting them into the next category.

Write-once Read-many (WORM) disc: Some optical discs can be recorded once. The

information stored on the disc can not be changed or erased. The discs commonly have

an organic dye recording layer between the substrate and the reflective layer. A strong

laser beam is focused on selected spots on the surface and pulsed. The energy melts the

film at that point, producing a non reflective void. In the read mode, a low power laser

is directed at the disc, and the bit information is recovered by sensing the presence or

absence of a reflected beam from the disc.

Re-writable, Write-many Read-many (WMRM) disc: Just like the magnetic storage

disks, allows information to be recorded and erased many times. Usually, there is a

separate erase cycle although this may be transparent to the user. Some modern devices

have this accomplished with one over write cycle. These devices are also called direct-

read-after-write (DRAW) discs. These discs typically contain an alloy recording layer

composed of a phase change material, most often AgInSbTe, an alloy of Silver, indium,

antimony and tellurium.

Developments of optical media<http://en.wikipedia.org/wiki/optical_disc#mw-head>

First generation

Optical discs were most commonly used to store music and computer software. The

laser disc format stored analog video signals for the distribution of home video, but

commercially lost to the VHS video cassette format, mainly due to its high cost and

non-recordability; other first generation disc formats were designed only to store digital

data and were not initially capable of use as a digital video medium.

Most first-generation disc devices had an infrared laser reading head. The minimum size

of the laser spot is proportional to the wave length of the laser, so wave length is a

limiting factor upon the amount of information that can be stored in a given physical

area on the disc. The infrared range is beyond the long wavelength end of the visible

light spectrum, so it supports less density than shorter wavelength visible light. One

67

example of high density data storage capacity, achieved with an infrared laser, is 700

MB of net user data for a 12 cm compact disc.

The first generation discs are :

• CD (Compact Disc) & its derivatives

VCD (Video Compact Disc)

SVCD (Super Video Compact Disc)

• LD (Laser Disc) : is a home video format and the first commercial optical disc

storage medium.

• GD-ROM (Gigabyte Disc Read-only Memory)

• PD (Phase-change Dual) : rewritable optical disc format introduced by

Panasonic in 1995.

• DDCD (Double Density Compact Disc)

• MO Disc (Magneto-Optical Disc) : rewritable optical disc that is used in

combination with magnetic technology.

• MD (Mini Disc) : Magneto optical disc-based data storage device initially

intended for storage of up to 74 minutes and later 80 minutes of digitized audio.

Second generation

The second generation optical discs were for storing great amounts of data, including

broadcast quality digital video.

The second generation optical discs are :

• DVD and its derivatives

DVD-audio

Dual-Disc : a type of double sided optical disc.

DIVX (Digital Video Express)

• Super Audio CD

• EVD (Enhanced Versatile Disc)

• DP (Data Play) : an optical disc system developed by Dataplay Inc. and released

to the market in 2002.

• UMD (Universal Media Disc) : an optical disc for use in play station, portable

handheld gaming and multimedia platform.

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• UDO (Ultra Density Optical) : Optical Disc format designed for high density

storage of high definition video and data.

Third generation

The third generation optical discs are in development, meant for distributing high-

definition video and support greater data storage capacities. These are :

• HD Disc (High Definition Disc)

BD (Blue-Ray Disc) : its storage capacity is upto 128 GB(quad-layer).

CBHD (China Blue High Definition Disc) : a derivative of the discontinued disc

format HD DVD

• FVD (Forward Versatile Disc)

• DMD (Digital Multilayer Disk) : an optical disc format developed by D. Data

Inc. It is based on the 3D optional data storage technology.

• FMD (Fluorescent Multilayer Disc) : an optional disc format developed by

Constellation 3D that uses fluorescent, rather than reflective materials to store

data.

Fourth generation

The following formats are going beyond the third generation discs and have the

potential to hold more than one terabyte (1TB) of data.

• HVD (Holographic Versatile Disc)

• LS-R (Laser-Selection-Type Recordable optional disc)

• PCD (Protein Coated Disc) : A PCD could enable 50 TB storage capacity.

Optical disc structure

Byers (2003) described the optical disc structure as below.

CDs and DVDs consist of the same basic materials and layers but are manufactured

differently. A DVD is actually like two thin CDs glued together. A CD is read from and

written to (by laser) on one side only; a DVD can be read from or written to one or both

sides, depending on how the disc was manufactured. Recordable DVDs (DVD-R, DVD-

RW, DVD-RAM) can be manufactured with one recording layer on each side.

69

Polycarbonate (plastic) substrate layer

The polycarbonate substrate makes up most of the disc, including the area that is read

by the laser (opposite the label side on CDs). It is present on both sides of a DVD, even

a “single sided” disc with a label on one side. This substrate provides the disc depth

necessary to maintain laser focus on the metal and data layers. It also gives the disc

enough strength to remain flat. Anything in or on the polycarbonate layer that interferes

with the ability of the laser to focus on the data layer will result in the misreading of

data. Accordingly, fingerprints, smudges or scratches, as well as such substances as dirt,

dust, solvents and excessive moisture (which polycarbonate will absorb), can interfere

with the ability of the laser to read the data. Contact of any foreign material with the

polycarbonate substrate layer should be avoided.

Data layer

As its name implies, the data layer of CDs and DVDs is the layer that contains the data.

The data appear as marks or pits that either absorb light from the laser beam or transmit

the light back to the laser photo sensor by way of the metal reflective layer. In CDs, the

data and metal layers are very close to the top of the disc (label side); in DVDs, they are

in the middle of the disc. The types of data and metal layers used depend on the type of

disc-read-only (ROM), write-once (R), or rewritable (RW, RAM).

The table below shows the relationship between the data and metal layers and the disc

type.

Table 4.2.3(A) : Disc type, read/record type, data layer and metal layer

CD- DVD- Type Data Layer Metal Layer

CD-ROM

Audio/Video

and PC use

DVD-ROM

Video/Audio

and PC use

Read only Molded Aluminium (also

silicon, gold or silver

in double layered

DVDs)

CD-R DVD-R

DVD+R

Recordable

(Write

once only)

Organic dye Gold, Silver or Silver

alloy

70

CD-RW DVD-RW

DVD+RW

DVD-RAM

Rewritable

(Write,

erase and

re-write)

Phase changing

metal alloy film

Alluminium

(Source: Byers (2003), NIST special publication 500-252, October, 2003)

Basic layers of CD-ROMs and DVD-ROMs (Byers,2003)

(Replicated discs for audio, video, computer use or interactive games)

(Source: Byers (2003), NIST special publication 500-252, October, 2003)

71

Metal (reflective) layers

The metal layer in optical discs reflects the laser beam back to the laser photo sensor in

the laser head. Three types of reflective metals are typically used for this layer :

aluminium, gold and silver or silver alloy. In “double-layer” DVDs, silicon is

sometimes used as one of the semi reflective layers.

Lacquer (metal protective) layer (CDs)

A very thin lacquer layer is applied to the label side of CDs to protect the metal from

exposure to the environment. DVDs have no such protective lacquer coating. Thin layer

also gives some limited protection from writing on or labeling the disc. The application

of lacquer completely around the edges of the disc is very important.

Optional surface layer

An optional layer may also be added to CDs/DVDs to provide a labeling surface. Such

surfaces are of four types:

• Thermal printable

• Inkjet printable

• Silkscreen printable

• A surface that will accommodate more than one type of printing.

These layers are applied over the lacquer layer on CDs or over polycarbonate substrate

on a single sided DVD.

Life expectancy of optical disc

The life expectancy of optional discs depend on many factors. Manufacturers have done

some testing and there is consensus that under recommended storage conditions, CD-R,

DVD-R and DVD+R discs should have a life expectancy of 100 to 200 years or more.

CD-RW, DVD-RW, DVD+RW and DVD-RAM discs should have a life expectancy of

25 years or more. In case of CD-ROM and DVD-ROM discs, life expectancy vary from

20 to 100 years (Byers,2003).

Factors for degradation of optical disc (Byers,2003)

Optical discs degrade through the passage of time. The following factors are identified

for affecting the optical discs.

72

• Type of disc

• Manufacturing quality

• Condition of the disc before recording

• Quality of the disc recording

• Handling and maintenance

• Environmental conditions

The different types of CD and DVD discs have different data layer materials-molded

aluminium, organic dye or phase changing film etc. Deterioration of these materials is

the primary cause of degradation of the discs. Sometimes microscopic pinholes develop

on the protective coating by exposure to high temperature, high humidity, high intensity

light and allow water molecules and airborne pollutants to penetrate onto the recording

and reflective layer. Imperfect sealing around the disc circumference is especially

damaging.

The corroded reflective layer seriously degrades its functions as an effective light

modulator, reducing the readout signal performances.

Some materials used in the label silk screening process are known to chemically react

with the reflective layer, lowering its reflectivity.

Environmental factors like temperature and relative humidity, light exposures,

moistures, organic solvents, magnetism, x-ray, micro waves and radiation can affect the

rate of disc degradation. In each of the three basic disc types, environmental forces will

degrade the data layer much faster than the polycarbonate substrate layer. Because

degradation of the data layer will render the disc unless well before the polycarbonate

begins to deteriorate, the relative degradation rate for the polycarbonate layer is not used

for life expectancy considerations.

Strong temperature and relative humidity ranges recommended in various technical

sources are presented in the table below:

73

Table 4.2.3(B): Recommended storage parameters from different sources

Source

Media Temperature Maximum

Temperature

Gradient

Relative

Humidity

(RH)

Maximum

RH

Gradient

ISOTC 171/SC,

Jan,2002

CD-R

CD-

ROM

+5° to 20°C

(41°F to68°F)

4°C/hr

(7°F/hr)

30% to

50%

10% /hr

IT 9.25 and ISO

18925, Feb-

2002

CDs

DVDs

-10°C to 23°C

(14°F to73°F)

20% to

50%

Cycling

no

Greater

than

±10%

NARA, FAQ

about Optical

media, April-

2001

CDs

DVDs

68°F

(20°C)

+/-1°F/day

(+/-

0.6°C/day)

40% 5% /day

National

Archives of

Australia,

April,1999

CDs 18°C to 20°C

(64°F to68°F)

45% to

50%

10% /

24hrs

Library

Technical

Report

Nov-Dec, 1997

CDs -10°C to 50°C

(16°F to122°F)

10% to

90%

DVD

Demystified

Second Edition

Jim Taylor,

2001

DVD-

R

DVD-

ROM

-20°C to 50°C

(-4°F to122°F)

15°C/hr

(27°F/hr)

5% to 90% 10% / hr

DVD-

RAM

-10°C to 50°C

(16°F to122°F)

10°C/hr

(18°F/hr)

3% to 85% 10% / hr

DVD+ -10°C to 55°C 15°C/hr 3% to 90% 10% / hr

74

RW

(14°F to131°F) (27°F/hr)

National

Library of

Canada, 1996

CDs 15°C to 20°C

(59°F to68°F)

2°C/24hrs

(9°F/24hrs)

25% to

45%

5% /

24hrs

Media Sciences,

Inc. Jerome L.

Hartke, July-

2001

CD-R 10°C to 15°C

(50°F to59°F)

20% to

50%

(Source: Byers (2003), NIST special publication 500-252, October, 2003)

Physical mishandling of the disc is usually the cause of polycarbonate layer damage.

Fingerprints, smudges, scratches, dirt, dust, solvents, moisture and any other foreign

materials can interfere with the ability of the laser to read the data. Light scratches and

fingerprints are very common and while they both can impede laser reading, their

effects on the disc are somewhat different.

4.3 Personnel Management

Staffing is a complete personnel function covering (a) employment and training of

employees and (b) maintenance of favorable environment for carrying out work. The

principal aim of a staffing programme is to employ efficient employees in adequate

number in the library who are capable in fulfilling the objectives of the library.

Required environment must be built up so that they feel motivated to put in their best.

When the information infrastructure becomes more complex, it is more likely that the

staff will be highly skilled in handling a variety of AV formats. They will have a basic

general skill level with high specialization in this area.

Categories of staff

The existing categories of staff in DDK libraries can be grouped as below:

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• Para professional

- Junior Library Attendant

- Library Attendant

- Library clerk

• Professional

- Library and Information Assistant

• Senior professional

- Assistant Library and Information Officer

- Library and Information Officer

- Senior Library and Information Officer

- Principal Library and Information Officer/ Director

In DDKs the para professional staff are not recognized as library and information

science professionals. Still there are a provision for Junior Library Attendant (JLA)

meant for middle pass standard and the Library Attendant (LA) and Senior Library

Attendant (SLA) which are promotional grades from JLA. On the other hand, the

Library clerk is the post of HSLC level. All the employees holding these posts,

obviously have experiences in day to day library activities and they are functioning as

para professional staff and contribute a lot in the dissemination of information.

The post of Library and Information Assistant (LIA) is of professional category at entry

level. The LIAs are the Bachelors of Library and Information Science with minimum of

professional qualification. The post of Assistant Library and Information Officer

(ALIO) onwards are the senior library and information science professionals.

Recruitment and promotional avenue

Some of the library staff are recruited directly and some of them are on promotional

basis. But some of them are filled up by both ways, either direct recruitment or on

promotion. The list of these posts and their specific procedures for recruitment and

promotion is given below:

1. Junior Library Attendant Direct entry Middle pass

2. Library Attendant Promotional Grade Middle pass

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3. Senior Library Attendant Promotional Grade Middle pass

4. Library Clerk Direct entry Matriculation

5. Library and Information Direct entry and Graduate + BLISc

Assistant ( LIA ) Promotional grade

From Library Clerk

6. Assistant Library and Direct entry and PG + BLISc + 3

Information Officer (ALIO) Promotional grade Years Experience

from LIA

7. Library and Information Direct entry and PG + BLISc + 7

Officer Promotional grade Years Experience

from ALIO

8. Senior Library and Direct entry and PG + BLISc + 10

Information Officer Promotional grade Years Experience

( SLIO ) from LIO

9. Principal Library and Direct entry and PG + MLISc + 12

Information Officer/ Promotional grade Years Experience

Director From SLIO

Though the above picture gives a clear provision for promotional avenue in DDK

libraries, it is unfortunately observed that although most of the LIAs were recruited

through Staff Selection Commission (SSC), it has come to light that some of the LIAs

are working more than 25 years even 30 years in some kendras, but no promotion has

been given to them till date. However they have been given financial upgradation under

Modified Assured Career Progression (MACP) Scheme.

In service training

The DD media authority organizes some training programmes which are designed to

meet the needs at different levels on different functions, such as library management,

programme production, technical competence, administrative and accounts

performances etc.

The library professionals are also given training on library automation, digitization of

library holdings, database management etc. Generally the training programmes are

77

arranged by the Regional Staff Training Institutes (RSTI) located at different parts of

the country. Sometimes they also make use of training programmes conducted by some

outside expert agencies.

The basic idea of manpower training is to

(1) create confidence in the newly coming technologies/ ideas

(2) Sharing of ideas/skills/experiences among the participant trainees

(3) Prepare themselves to face new challenges

(4) Broaden their outlook

(5) Achieve a high level of technical competence among staff

(6) Gain knowledge of policies and procedures etc.

4.4 Conclusion

The effective management enables the users to have faster and more convenient access

to the contents of the AV media. The obsolescence of the AV materials necessitates the

archived materials to be migrated to the new AV materials. The management technique

of all AV libraries in DDKs is almost similar except few variations found from kendra

to kendra. The manual processing of all basic library functions has put the whole image

of the TV media library system into a backward position in comparison to the other

libraries where all possible information technologies are being applied. The ARCLIB

tape database management system software which has been created for in-house use in

DDK libraries only is not yet been popularized among the library professionals.

Preservation methods in Indian TV media libraries have been found not up to the mark.

Excepting the process of transferring the valued contents of the AV materials to the new

AV materials, no other techniques like maintenance of tapes, application of

dehumidifiers, vacuum cleaners etc. are popularly adopted. All these attempts have

remained occasional. Digitization of AV contents in file formats is only anticipated as

effective method of preservation.

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