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Robust Compression and Transmission of MPEG4 Video

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... to recover data after errors, and to visually conceal the effect of errors. ... estimate macroblock movement so that more accurate concealment can be performed. ... – PowerPoint PPT presentation

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Title: Robust Compression and Transmission of MPEG4 Video


1
Robust Compression and Transmission of MPEG-4
Video
  • ACM Multimedia, Oct 1999
  • Steven Gringeri ,Roman Egorov, Khaled Shuaib,
  • Arianne Lewis and Bert Basch

2
Outline
  • Introduction
  • Overview of MPEG-4 Standards
  • Error Resilience Features in MPEG-4
  • Error handling in Decoding MPEG-4
  • MPEG-4 Video Performance Experiments
  • Conclusions

3
Introduction
  • With variable length code,the transmission errors
    can cause the decoder to incorrectly determine a
    code words length leading to loss of
    synchronization between the decoder and the
    stream.
  • Predictive coding techniques allow errors to
    propagate thus degrading video quality.

4
Introduction(cont.)
  • MPEG-4 standards define a set of special error
    resiliency tools to handle these issues.

5
Overview of MPEG-4 Standards
  • The MPEG-4 standards present a scene as a set of
    audiovisual objects.
  • An MPEG-4 stream contains three major types of
    video object planes(I-VOP,P-VOP,B-VOP).

6
Overview of MPEG-4 Standards(cont.)
7
Overview of MPEG-4 Standards(cont.)
  • MPEG-4 standards support object-based coding
    where each object in a video scene can be coded
    as a separate bit stream and where both natural
    and synthetic objects can be mixed.

8
Overview of MPEG-4 Standards(cont.)
9
Error Resilience Features in MPEG-4
  • The MPEG-4 standards provide built-in error
    resilience capabilities to detect and localize
    errors, to recover data after errors, and to
    visually conceal the effect of errors.
  • Resynchronization markers
  • Data partition
  • Header protection
  • Reversible variable length code

10
Error Localization
  • Resynchronization markers
  • Data partition

11
Error Localization(cont.)
12
Error Localization(cont.)
13
Error Localization(cont.)
14
Intra Frame Refresh
15
Error Handling in Decoding MPEG-4
  • When an error is detected in a video packet, the
    damaged macroblocks must be discarded.
  • The simplest approach is to leave the affected
    region unchanged until the next undamaged intra
    coded macroblock is available.
  • If motion information is undamaged,it can be used
    to estimate macroblock movement so that more
    accurate concealment can be performed.

16
MPEG-4 Video Performance Experiments
  • NM image

17
Effect of Bit Errors on Video Quality
18
Effect of Bit Errors on Video Quality(cont.)
19
Effect of Bit Errors on Video Quality(cont.)
20
Effects of Packet Size and Boundaries on Video
Quality
21
Localizing Errors Using Packet Video
22
Localizing Errors Using Packet Video(cont.)
23
Error Correcting Codes
  • BCH code (n,k)
  • n n bits
  • k protect k bits
  • t the maximun number of errors that a code can
    correct

24
Error Correcting Codes(cont.)
  • PB post-decoder BER

25
Error Correcting Codes(cont.)
26
Conclusion
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