Multimedia entertainment and security1 Multimedia Entertainment and Security Submitted by: Sravanthi. Y

Multimedia entertainment and security 1

Multimedia Entertainment and Security

Submitted by:

Sravanthi. Y


Outline : Introduction Services of multimedia Challenges of MM over wireless Multimedia Security Image Security Video Security Audio Security Audio Video Mixing Conclusion References


What is Multimedia?????

The term multi-media means that there are more than one media type involved in the communication, e.g. text and graphics, voice animations, video and audio.


Multimedia Services

2,000

0

32

64

9.6

128

144

384

1G 2G 3G

VoiceVoice

Text MessagingText Messaging

Video StreamingVideo Streaming

Still Still ImagingImaging

Audio StreamingAudio Streaming

Da

ta T

ran

sm

iss

ion

Sp

ee

d -

k b

ps

ElectronicNewspaper

RemoteMedical Service(Medical image)

Video Conference(High quality)

Telephone (Voice)

Voice Mail

E-MailFax

ElectronicPublishing

Karaoke

Video Conference(Lower quality)

JPEG Still Photos

Mobile Radio

Video Surveillance,Video Mail, Travel

Image

Audio

Voice-driven Web PagesStreaming Audio

DataWeather, Traffic, News,Sports, Stock updates

Mobile TV

E-Commerce

Video on Demand:Sports, News Weather

Reference:http://www.cse.fau.edu/~borko/PP,ChallengesWireless%20MM.ppt


Challenges of MM over wireless:MM applications over a wireless channel require:

High data rates Reliable connection More memory High resolution displays High processing units Quality of service factors Problem of portability with wireless Security


Characteristics of MM Applications


QoS Requirements for MM (Real-time)


Security ????


SENDER RECEIVER

THIRD PARTY INTERRUPTION

Multimedia security for : Content Protection, Protecting copy rights of sender

Is the data

credible


Security in MMDigital Watermarking: Digital water marking is a process that

embeds an imperceptible signature or watermark in digital file containing audio, image, text or voice data.

Watermark can be a binary data, a logo or random numbers with a certain distribution.

Watermarking Algorithm

WatermarkedImage Ì

Stego-Image I

Watermark W

Secret / public key K



Advantages: Watermark is invisible Easy to detect and hard to remove Combats fraudulent use of wireless communications Authenticating the identity of cell phones and

transmission stations Secured delivery of mm applications (audio, video

and images);Disadvantages: Expensive Adds to the drain of the available energy in handheld

devices.


Issues:

Security in Image transfer

Security in Video transfer

Security in Audio transfer


Issue 1: Image Security

Reference: http://www.ics.uci.edu/~forge/papers/dac04.pdf

Issue :It is very easy to reproduce multimedia image with out damage, crop images and change the content of images.


Some examples :


Solution : Image Watermarking


Target System Architecture:


Components :

Mobile or hand-held device Content Server ( stores multimedia and

data base content and stream data (say images) to a client as per requests.

Proxy servers – compress/decompress images, transcode video in real-time, provide/access directory services.


Implementation Step 1:There are three basic tasks in watermarking

with respect to imaging: Embedding:


DWTOriginal image

watermark

Watermarked image

Insertion procedure:


Steps 2 & 3: Detection and Extraction: Detecting

whether an image has a watermark and extracting watermark from the image by applying the reverse process of embedding.

Authentication : refers comparing the extracted watermark with the orginal watermark.



Wavelet- based Watermarking

Insertion and extraction procedure


Issue 2: Audio Security

Reference: www.fxpal.com/publications/FXPAL-PR-03-212.pdf

Unauthorized tapping, copying, redistribution, removal or embedding of data –Audio piracy


According to IFPI…… The water mark should not degrade the

perception of audio. The algorithm must offer more than 20dB

of SNR for water mark audio and 20 bps data payload for watermark.

The watermark must resist most common audio processing operations.

Watermark must prevent unauthorized copying, redistribution, removal or embedding of data –data piracy


Solution

Audio Watermarking : Time based modulation


Audio Watermarking Changing the time duration of an audio

sample with out changing the pitch or other spectral characteristics

These small amounts of time scale modifications are not noticeable.

Short time regions of the signal are either compressed or expanded by an imperceptible amount - “time base modulation”



How is it done??? Time-alignment of the watermarked and

reference audio produces a “tempo map” that indicates how the time base of the watermarked audio has been altered.

In regions of compression or expansion, the tempo map will deviate from a straight line and the embedded watermark data may be recovered from these deviations. Though this method will not work on audio with undetectable spectral change, such as silence,




Signal x(t) expressed as the concatenation of K non-overlapping blocks,x1…..k, with concatenation denoted by C.

The watermarked signal, xw(t)..



Issue 3: Video Security

Unlimited duplication, piracy and unauthorized access and distribution of video.

Reference: http://www.cse.cuhk.edu.hk/~lyu/paper_pdf/icdat05.pdf

Solution : Video Watermarking


Solution: Video Watermarking

Watermark remains intact even when the decrypted signal is converted from digital to analog.

Transparency : Invisibility of water mark with out affecting the video quality.

Robustness: watermark is not removable by any attacks, including frame dropping, compression, cropping, resampling.....


Implementation of Video watermarking Step 1: Video is taken as input , perform

scene change detection by histogram difference method.

Video divided into frames.


GOP - Frames 3 types of frames: I-frames (frames independent of other

frames). P-frames (frames predicted from I-frames). B-frames ( Between P-frames &i-frames for

motion compensation).


Watermark PreprocessIf size of image = 64.2p X 64.2q

p + q = n ; p, q<0; 2n≦m,

Divide the image into 2n small images with size 64 X 64


Video Water marking

Embedding algorithm


Implementation (contd..) Step 2: Applying DWT to video &

watermark.

Step 3: Embedding Algorithm :


Watermark embedding Some applications require real-time

watermark embedding. Frames with high degree of similarity

cannot have different watermarks. Embedding the same watermark in all

frames may be insecure. Embedding a watermark must not

significantly increase the data rate of the watermarked video stream.


Combination of watermark with scenes


Scene Change Detection


Experimental results

Extracted watermark from different attacks

Dropping and averaging

Compression

Increase brightness

Cropping some regions

Dropping all frames with the 5th part of watermark


Is this a good approach????

Watermarked Video Frames

Watermarked Audio


Is this a good approach??? (contd..)

Difference in delays

Missing frames or audio packets

Attack against integrity

Lip synchronization


Combined Audio Video

watermarking

Synchronization based approach


Synchronization based approach: Inserts a time code as a watermark into

multimedia data in a efficient manner. time code format : hh:mm:ss:ff (f-frame) Well known synchronization time code is

SMPTE

Each position in a multimedia stream would include a complete timing information;


Implementation:Step 1: Inserting an absolute time code into

a/v streams.Absolute time

code

Relative time code


Range of time code {0-12},{0-59}, {0-59}

This can be encoded with 4+6+6 = 16 bits

01: 35: 45 = 00 01 11 101 100 101


Time code transferred to a Watermark

01:35:45 0001 011101 100101

Time

Secret key

Watermarking patternBit vector


Loop hole:

The features of audio/video content extraction are a subject to further research.

(The reliability of audio signal varies with different audio categories).


Conclusion & Future Direction: Watermarking is a good solution for

transfer of multimedia through an unsecured wireless channel and with out effecting the quality of data.

Watermarking can be improved with error coding and compression techniques.


References:[1]. Borko Furht, ”Challenges in Wireless Multimedia” CSE Department Seminar

Series, September 2003

[2]. Arun Kejrariwal, Sumit Gupta, Alexanderu Nicolau, Nikil Dutt, Rajesh, “Proxy based task Partitioning of watermarking Algorithms for reducing Energy

Consumption in Mobile Devices” October 2004

[3]. Jonathan Foote, John Adcock and Andreas Girgensohn, “Time Based Modulation: A new Approach to Watermarking”, July 2005

[4]. Pik-Wah Chan, Michael R.Lyu, “ Digital Video Watermarking with a genetic Algorithm”, computer science and Engineering Department, the Chineese University of Hongkong, March 2004

[5]. Jana Dittman, Martin Steinebach, Ivica Rimac, Stephan Fischer, and Ralf Steinmetz, “Combined video and audio watermarking: Embedding content information in multimedia data” GMD- German national research Center for Information Technology,


Questions ????

Documents

Multimedia entertainment and security1 Multimedia Entertainment and Security Submitted by: Sravanthi. Y