M P E G

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M P E G
A Presentation by Sebastian Graf and Thomas
Winterscheid
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Topics

• What is MPEG?
• Different MPEG Standards
• What is a movie?
• The MPEG video compression
• Conclusion

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What is MPEG?
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What is MPEG exactly?

• Moving Picture Experts Group
• Established in 1988
• The convener of the MPEG group is Dr. Leonardo
  Chiariglione
• Vice president of Multimedia Telecom Italia Lab
• http//leonardo.telecomitalialab.com/

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What is MPEG exactly?

• Comission directed by ISO an IEC
• Develops standards for video and audio coding
• Nickname given to a family of international
  standards

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Approved MPEG Standards

• MPEG-1 Nov. 92
• MPEG-2 Nov. 94
• MPEG-4
• Version 1 Oct. 98
• Version 2 Dec 99

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Planned for the future...

• MPEG-4
• Version 3,4 and 5
• MPEG-7
• MPEG-21

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MPEG-1

• Quality VHS video
• Originally for 1x CD-ROM drives (1,4 MBit/s)
• Constant datarate
• Standard for Video CDs

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MPEG-2

• HDTV (High Definition TeleVision)
• Premiere World (lower rates for more chan.)
• Still important for new digital TV norms
• DVD
• Variable datarates

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MPEG-3 ?

• MPEG-3 standard was under construction, but never
  finished
• Was planned for newer HDTV
• Parts of technology and techniques are
  implemented in MPEG-2

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Overview
Datarate/ Resolution
Advantages
Disadvantages
Scope
1,4 Mbit/325x288 High Compression Audiocodec Assymetric compression Only in SIF Format Codec for Multimedia files on your PC
4 Mbit/325x288 15 Mbit/720x576 60 Mbit/1440x1152 80 Mbit/1920x1152 Different Formats Supports Dolby Surround Much more complicated as MPEG-1 Multimedia PC Digital TV Satellite TV
MPEG-1
MPEG-2
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The Future MPEG-7

• Planned to be released in fall 2001
• Is formally called Multimedia Content
  Description Interface
• Includes a new standard of handling DDL
• More easier to implement into multimedia
• Intends to be an allrounder for all multimedia
  formats

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The Future MPEG-7

• MPEG 1-2-4 wont be replaced by MPEG-7
• Works indepentend of its predecessors
• Because of file description data query in special
  multimedia databank is possible
• Several search options will be included
• But this isnt enough................

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More Future MPEG-21

• Development is running, planned to be finished in
  2003
• Includes a new description language (DIDL)
• Universal player for all standards
• Multimedia files are more communicative
• And also there is to say...............

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More Future MPEG-21

• The general goal of MPEG-21 activities is to
  describe an open framework which allows the
  integration of all components of a delivery chain
  necessary to generate, use, manipulate, manage,
  and deliver multimedia content across a wide
  range of networks and devices.
• http//ipsi.fhg.de/delite/Projects/MPEG7/Mpeg21.h
  tml

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Topics

• What is MPEG?
• Different MPEG Standards
• What is a movie?
• The MPEG video compression
• Conclusion

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What is a movie?
video track
timecode
audio track
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What is a movie?
timecode
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encode or decode?

• encoder

• decoder

100111010011
100111010011
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MPEG video compression
movie picture 1
movie picture 2
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MPEG video compression

• High similarity of 2 successive pictures
• gt correlation
• Same pixels movement in Camera turns
• gtmotion compensation
• DCT quantization

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MPEG video compression

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The block layer

• Picture is divided in 8x8 blocks (JPEG)
• The blocks are processed independent from each
  other
• DCT
• Quantization

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DCT Quantization

• Very similar to the fourier transformation
• Information are transformed to a
  frequenz-exhibition (nearly no data loss)
• Matrix of DCT-coefficients
• Coefficients are divided by quantization values
  (given by the JPEG group) and then rounded to the
  next integer value

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Discrete Cosinus Transformation
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The macro layer

• I Frame, P Frame or B Frame?

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The macro layer

• I Frames
• intra coded image
• highest amount of data
• coding is very similar to a JPEG picture
• can be processed independent from other frames
• have a specified distance to the next I-Frame

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The macro layer

• B Frames
• bi-directionally interpolated image
• lowest amount of data
• most frequent type of frame
• depending on the previous or following P /
  I-Frame
• can also depend on the previous and following
  frame

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The macro layer

• P Frames
• predicted image
• medium amount of data
• difference to the previous I Frame is stored
• have motion compensation ability

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The macro layer

• Motion Compensation in P Frames

I - Frame
P - Frame
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The slice layer

• Slices are a group of succesive macro-blocks
• There is no dependence of slices on each other

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The picture layer
Display
Datastream
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The group of picture layer

• Unrestricted number of pictures in their natural
  sequence
• At least one I-Frame per GOP
• Quantization values can be different for each GOP

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The sequence layer

• Union of GOPs
• Movie width
• Movie height
• Movie format (e.g. 43 / 169)
• Framerate (fps)
• Bit-rate

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Conclusion

• MPEG is a very common standard
• Look forward to the new codec technologies
• Contains numerous new features
• New standards will be much more user
  friendly
• Many options to adjust the compression
• Even better techniques for even better quality

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Any questions?
    leonardo.chiariglione_at_tilab.com
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Thanks for your attention...