Multimedia Standards MPEG 0360520 Section 2 Winter 2003

Multimedia Standards MPEG 0360520 Section 2 Winter 2003 Instructor: Dr. Ritu Presented by Jijun(Justin) Huang

OUTLINE • • • Introduction MPEG Overview MPEG Standards – – – MPEG-1 MPEG-2 MPEG-4 MPEG-7 MPEG-21 • Influence of Other Standards to MPEG • Implementation Areas • Conclusion

INTRODUCTION • MPEG is a working group of the ISO/IEC. – – – MPEG (Moving Pictures Expert Group) ISO (International Organization for Standardization) IEC (International Electronics Commission) • The aim of MPEG is: – compression, – decompression, – processing, – and coded representation of video, audio, and their combination.

MPEG Video Overview • Idea is to remove – Spatial redundancy: • Discrete Cosine Transform (DCT) is used: – Transforms a video frame from spatial domain into a frequency domain. – Temporal redundancy • Motion-compensation is used: – Encodes a video frame based on other video frames which are temporally close to it.

MPEG Video Format • A video stream is a sequence of video frames – digitized in a standard RGB format, 24 bits per pixel; • 8 bits for each Red, Green, and Blue. – RGB format must be converted to YUV format: • Represented in 24 bits per pixel: – 8 bits for each Y, U, and V information.

MPEG Video Format • In MPEG-1 images represented in YUV color space (YCb. Cr) – Frame is divided into macro blocks of 16 x 16 pixels • 4 luminance blocks and • 2 chrominance blocks. – Every block has a dimension of 8 x 8 values • all luminance inf. (Y) are kept as it is, • chrominance inf. is divided into 2 parts (Cb and Cr)

MPEG Video Format • This subsampling is a lossy step and • Does not affect the quality • The 24 bits RGB format --> 12 bits YUV inf. , • which gives 2: 1 compression • MPEG-1 allows video compression ratio: • 50: 1 to 100: 1

MPEG Frame Encoding • A MPEG “film” is a sequence of : – I- frames: is a still image, – P-frames: are forward predicted from last I or P frame – B-frames: are both forward & backward predicted from the last/next I or P frame • Frame is divided into macro blocks of 16 x 16 pixels – Depending on the kind of macro block: • blocks contain pixel information or • prediction error information. – The information is compressed using the DCT.

MPEG Frame Encoding • Macro blocks are units for motion-compensated compr. – Blocks are used for DCT compression. – I- frames: encoded as a single image, • Each 8 x 8 block transformed into a freq. domain • Data is encoded in a zig-zag ordering – P-frames: encoded relative to the past reference frame; • Encoded either as an I-macroblock or P-macroblock. – B-frames: encoded relative to the past/future or both reference frame. • Encoded similar to P-frames

MPEG Audio • To compress audio MPEG tries to remove: – The irrelevant parts, and – Redundant parts. • Parts of the sound that we don’t hear: • Can be thrown away. – MPEG Audio uses psycho-acoustic principles.

MPEG STANDARDS • MPEG-1: (release in 1993, ISO 11172) – Standard for • storage and • retrieval of video and audio on digital storage media. – Provides video compression rate: • Around 1. 5 Mbit/s. – Provides audio compression rate: • Around 32 Kbit/s to 384 Kbit/s.

Description of MPEG-1 System • Synchronized video and audio with timing information • 90 k. Hz system clock

MPEG STANDARDS (continued) • MPEG-2: (1994, ISO 13818) • Standard for digital television. • Tires for a higher resolution. – A color resolution in: • MPEG-1: 4: 2: 0 YCb. Cr • MPEG-2: 4: 2: 2 YCb. Cr • Support video transmission about 2 -80 Mbits/s.

Description of MPEG-2 System – PES Packetised Elementary Streams – PS: combines 1 or more PES with a common time base into a stream – TS: combines 1 or more PES with 1 or more independent time base

MPEG STANDARDS (continued) • MPEG-4: (1998, ISO 14496; version 2, late 2001) – Include the ability to represent as a single object, and – Audio, video, synthetic audio, graphics, image, etc. – multiplex and synch. to form complex appearance. – aims to provide a set of technologies to: • Satisfy the needs of authors • Service providers • End users By avoiding incompatible formats and players. – MPEG-4 video encodes frames into YUVA format.

MPEG STANDARDS (continued) • MPEG-7: (release late 2001, ISO 15938) – common interface for describing multimedia materials. – MPEG-7 aims to standardize: • A set of Description Schemes and Descriptors to describe data • A language to specify Description Schemes, and • A scheme for coding the description – MPEG-7 goals • Describe multimedia content • Manage data flexibly, and • Globalize data resources

MPEG STANDARDS(continued) • MPEG-21 1. Describes “big picture” across wide range of networks 2. Creates framework for multimedia delivery and consumption 3. Transparent use of multimedia resources across networks 4. Provides access to information and services from almost anywhere at anytime with terminals and networks

MPEG-21 Parts • Vision, Technologies and Strategy – Technical roadmap, identify key steps in value chain • Digital Item Declaration (DID) – Schema defining the structure of a digital item (resources + descriptors) • Digital Item Identification & Description (DII & D) – Provides a tools to identify a Digital Item • Intellectual Property Management & Protection • Rights Data Directory ( RDD) deal with • Rights Expression Language ( REL) digital rights • Digital Item Adaptation ( DIA)

Influence of Other Standards – SGML (Standard Generalized Markup Language ): provides a good Standard Generalized Markup Language example for MPEG’s DDL (Description Definition Language) ü Structuring ü Describing content – XML: XML Schema Language is used for the basis of it. – Hy. Time: parts of the standard are considered; Ø Too generic Ø Difficult to understand handle

DDL and XML Bruce Willis Bo Weinberg An example: • A web site about boxing • Huge database • Advanced queries on keywords describing certain events in the video files

Boxing DDL example .

Tyson knocks some poor sap out

Implementation Areas • Social and economic issues : – Education – Surveillance – Shopping – Film, video, and radio archives – Geographical Information Systems (GIS) – Face recognition technology

CONCLUSION • MPEG-1: Audio & video coding for digital storage • MPEG-2: For Digital TV ( DVD, Satellite) • MPEG-4: For coding of audio & video objects • MPEG-7: Identifies and manages audio-video content; multimedia indexing, standardizes a set of high level schemas (XML-Schema) • MPEG-21: Multimedia Framework. . . • The complexity of streams are increasing …. • They are making the work enjoyable with computer.

REFERENCES [1] S. Battista, F. Casalino, C. Lande, “MPEG-4: A Multimedia Standard for the Lande Third Millennium, Part 2”, IEEE Multimedia, Vol. 7, No. 1, 2000, pp. 76 -84 [2] S. Battista, F. Casalino, C. Lande, “MPEG-4: A Multimedia Standard for the Third Millennium, Part 1”, IEEE Multimedia, Vol. 6, No. 4, 1999, pp. 74 -83 [3] F. Nack, A. T. Lindsay, “Everything You Wanted to Know About MPEG-7: Part 1”, IEEE Multimedia, Vol. 6, No. 3, 1999, pp. 65 -76 [4] F. Nack, A. T. Lindsay, “Everything You Wanted to Know About MPEG-7: Part 2”, IEEE Multimedia, Vol. 6, No. 4, 1999, pp. 64 -73 [5] S. Gringeri, R. Egorov, K. Shuaib, A. Lewis, B. Basch, “Robust Compression and Transmission of MPEG-4 Video”, 7 th ACM International Conference on Multimedia, Part I, 1999 [6] http: //mpeg. telecomitalialab. com/standards/mpeg-1. htm [7] http: //www. crs 4. it/~luigi/MPEG/mpeg 2. htm

Thank you!