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Multimedia Standards MPEG

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.

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Multimedia Standards MPEG

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

  2. 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

  3. INTRODUCTION • MPEGis a working group of theISO/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.

  4. 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.

  5. 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.

  6. MPEG Video Format • In MPEG-1 images represented in YUV color space (YCbCr) • Frame is divided into macro blocks of 16x16 pixels • 4 luminance blocks and • 2 chrominance blocks. • Every block has a dimension of 8x8 values • all luminance inf. (Y) are kept as it is, • chrominance inf. is divided into 2 parts (Cb and Cr)

  7. 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

  8. 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 16x16 pixels • Depending on the kind of macro block: • blocks contain pixel information or • prediction error information. • The information is compressed using the DCT.

  9. 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 8x8 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

  10. 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.

  11. 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 32Kbit/s to 384Kbit/s.

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

  13. 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 YCbCr • MPEG-2: 4:2:2 YCbCr • Support video transmission about 2-80 Mbits/s.

  14. 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

  15. 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.

  16. 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

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

  18. 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)

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

  20. DDL and XML • <Character-info> • <Actor>Bruce Willis</Actor> • <Character name>Bo Weinberg</Character name> • </Character-info> An example: • A web site about boxing • Huge database • Advanced queries on keywords describing certain events in the video files

  21. Boxing DDL example • <Mpeg7> • . • <Video> • <TemporalDecomposition> • <VideoSegment> • <TextAnnotation type = “Scene description” > • <FreeTextAnnotation>Tyson knocks some poor sap out</FreeTextAnnotation> • </TextAnnotation> • <MediaTime> • <MediaTimePoint>T00:01:00:0F24 </MediaTimePoint>...

  22. Tyson knocks some poor sap out

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

  24. 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.

  25. REFERENCES [1] S. Battista, F. Casalino, C. Lande, “MPEG-4: A Multimedia Standard for the 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”, 7th ACM International Conference on Multimedia, Part I, 1999 [6] http://mpeg.telecomitalialab.com/standards/mpeg-1/mpeg-1.htm http://www.crs4.it/~luigi/MPEG/mpeg2.htm [7]

  26. Thank you!

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