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Summary MPEG-1 MPEG-1(1988-1993)
-Goal: coding of moving picture with associated audio at rate up to 1.5Mbps-Entertainment and storage-Video storage with VHS quality-Video CD is full application of MPEG-1-3 layers in audio coding.
-Audio Layer 3 is the famous MP3
Summary MPEG-2
MPEG-2(1990-1995)- Higher bit rate at 80Mbps- mainly broadcast- Application in DVD, HDTV etc.- Backward compatibility with MPEG-1
Summary MPEG-4
MPEG-4 embraces several areas: Coding of visual objects Coding of audio objects Scene description and user
interaction Most important: object coding This set the stage for MPEG-7.
Why MPEG-7? Let’s take a step back! Almost all standards up to this point
involve either some form of waveform coding (e.g. linear prediction etc) or transform coding (e.g. DCT etc).
Look at linear prediction, for example. Speech waveforms are modeled as
output of a filter.
Why MPEG-7? Now, given the input to the filter
and the filter coefficients we can reconstruct the waveform, albeit with some distortion.
{Waveform } {input, filter coeffs}
Hence, we have a different (more efficient) representation of the waveform.
Represented by
Why MPEG-7?
Now look at transform coding.
Data block ---------------------> ------------ --------
Transform allows data to be ‘rotated’ to bring out the structure of the waveform for efficient coding.
T Q T-1
New representation
Why MPEG-7?
Classical Fourier Series expansion is an example Need uncountably infinite number of
‘samples’ to represent a sinusoid in time domain
Fourier series expansion needs only 3 parameters to represent the same signal
{sinusoid} {ω0, 2 FS coefficients.}
Represented by
Why MPEG-7? One motivation for MPEG-7 is to allow
meaningful search for data. We are missing one thing in our
picture. MPEG-7 allows us to go one step
further. It gives meaning to the ‘bits’ by
allowing metadata. Or ‘information’ about ‘information’.
Link between MPEG-4 and MPEG-7 MPEG-4 codes contents as objects. But an object can be described in many
different ways, just like how we can describe the object ‘apple’ in for example French, English, Russian etc.
MPEG-7 defines the ‘universal language’ as to how these objects are described and the ‘grammar’ as to how ‘sentences’ of these objects can be made.
MPEG-7(1998-2001) Also known as ’Multimedia Content Description
Interface’. An ISO/IEC standard Strictly speaking, MPEG-7 is not a data
compression scheme. MPEG-7 is mainly a software implementation. MPEG-7 specifies the rules as to how to describe
audiovisual data content whereas MPEG-1,2 and 4 make content available.
MPEG-7 is not targeted at specific application. It aims to be as generic as possible for further extension.
Main elements MPEG-7 consists of 3 parts:
Description tools (like tool box in Matlab):
-Descriptors (D) -Description Schemes (DS).
Description Definition Language (DDL). System tools.
Multimedia Description Tools:
Descriptors (D): just like ‘data types’ in Matlab Describes low-level audio or visual features such
as color, motion, texture etc as well as audiovisual content such as location, time etc
Description Schemes (DS): Just like ‘functions’ in Matlab Describes high-level audiovisual (AV) features
such as regions, segments, events etc. DS not only describes relationships among D’s, but relationships among basic DS’s as well.
Description Tools:
Over 100 description tools (just like Matlab toolboxes) have been defined. They can be divided as follows:
Basic datatypes
Links & media localization
Basic Tools
Models
Basic elements
Navigation & Access
Content management
Content description
Collections
Summaries
Variations
Content organization
Creation & Production
Media Usage
Semantic aspects
Structural aspects
User interaction
User Preferences
Schema Tools
User History Views Views
Other Multimedia Description Tools
MPEG-7 have a general set of multimedia Description Tools.
From this general set 2 other sets are defined: MPEG-7 Visual: Description tools
dealing with only visual description. MPEG-7 Audio: Description tools
dealing with only audio description.
Description Definition Language (DDL). DDL is based on XML schema Language. Since XML is not specifically designed
for audiovisual description and real-time usage, it has been extended by MPEG-7 to suite the purpose.
DDL defines syntax as to how D’s and DS’s can be described and combined.
DDL allows designers to create their own D’s and DS’s.
System Tools
A set of tools that support binary representation of D’s and DS’s.
Broadly, they are divided into 2 groups: Textual format (TeM) Binary format (BiM)
Problem in searching
Let’s go back to the problem of searching using MPEG-7
3. Spatial edge distribution
2. Spatial color distribution
4. Object shape
1. Color histogram
Other uses of MPEG-7
Digital libraries Multimedia directory services (e.g.
Tourist information, Geographical information systems)
Home Entertainment And many more!
What is next? MPEG is developing another
standard, called MPEG-21. Alternatively known as ‘Multimedia
Framework’. The goal is interoperability. It promises an environment where
delivery and use of all content types will be possible.
Summary Development of MPEG family
MPEG-1 and MPEG-2 are data compression MPEG-4 is the start to toward data
description (object coding). MPEG-7 is data description
Move from merely data compression to data description
Next step is interoperability (MPEG-21)
Bibliography Tarbell, Richard: MPEG-1 slides Tian, Dihong: MPEG-2 slides Dechaza, Olivier: MPEG-4 slides Martinez,Jose: ‘MPEG-7 Overview’ Chiariglione, Leonardo: ‘MPEG: achievements and
current work’ Chiariglione, Leonardo: ‘The MPEG generation, new
information-age elements’ Koenen, Rob: ‘Object-based MPEG offers flexibility’ at
www.eetimes.com Day, Neil; Martinez Jose: ‘Introduction to MPEG-7(V4.0)’ http://www.chiariglione.org/mpeg/ http://www.mpegif.org/resources.php