MPEG4 Codec for Access Grids
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MPEG4 Codec for Access Grids National Center for High Performance Computing Speaker: Barz Hsu Email: [email protected] 11/11/2004. Outline. Definition of HDTV Brief Introduction to MPEG-4 Standard History and Problems of VIC Contributions. What’s High Definition Video?.

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MPEG4 Codec for Access Grids

National Center for High Performance Computing

Speaker: Barz Hsu

Email: [email protected]

11/11/2004


Outline
Outline

  • Definition of HDTV

  • Brief Introduction to MPEG-4 Standard

  • History and Problems of VIC

  • Contributions


What s high definition video
What’s High Definition Video?

  • Frame Resolution:

    >= 720x480 or 640x480

  • Frame Rate

    >= 20 fps

  • Peak Signal to Noise Ratio (PSNR)

    >= 30 dB


Another key factors for access grids
Another Key Factors for Access Grids

  • Real-Time

    • Minimize latency & jitter

  • Error Resilience

    • RTP over UDP is unreliable

  • Large Scale Video Conferencing

    • Selection of suitable coding tools

    • Optimization

  • Adaptive

    • network bandwidth

    • computing resources


Status of mpeg4
Status of MPEG4

  • Part 2: Advanced Simple Profile (ASP)

  • Part 10: Advanced Video Coding (AVC or H.264)

  • Match MPEG-2 quality at up to half data rate

  • Deliver excellent video quality across entire bandwidth spectrum – from 3G to HD

    • (from 40Kbps to 10MBps)



Interoperability issues
Interoperability Issues

  • Communicate with Polycom, iChat AV (Tiger)

  • Transport Stream

    • RFC 3016: RTP Payload Format for MPEG-4 Audio/Visual Streams.

    • RFC 3640: RTP Payload Format for Transport of MPEG-4 Elementary Streams

    • MPEG2TS


Vic vi deo conferencing t ool
VIC: Video Conferencing Tool

  • Developed by Network Research Group in U.C. Berkeley

  • Mbone Tools used by Access Grid, inSORS, and VRVS

    • vic for video and rat for audio

  • Based on RTP/RTCP to provide real-time video

  • Support Multicast/Unicast Protocol

  • Hybrid of Tcl/Tk and C++

  • Supported codecs

    • H.261, H.263, H.263++, MJPEG, nv, and etc.


The problems of vic
The Problems of VIC

  • Hard to maintain

  • Lack of high-quality video codec

    • only H.261 is relative useable

  • Limitation on frame resolution

    • Only QCIF (176x144), CIF (352x288)

  • Limitation on viewing resolution

  • Lack of exhaustive optimization oncodec, render, grabber, and etc


Our goal
Our Goal

  • Broadcast in Television Quality

    • Leverage with Existing Open Source Resources

      • VLC, MPlayer, and FFmpeg

    • Providing “Sense of Presence”

    • As Real-Time As Possible

    • High-Definition, High Quality

    • Incorporate with up-to-date codecs such as MPEG2, MPEG4 (ASP), H.264

    • Less Compression Artifact

    • Error Resilience/Concealment


Mpeg4 codec
MPEG4 Codec

  • Related Open Source Project

    • FFmpeg, xvid, and sklmp4

  • FFmpeg/libavcodec

    • High performance of CPU usage

    • Support various codec

      • MPEG4, MPEG2, MPEG1

      • H.263++, H.263, H.261

    • Provide error resilience tools

      • slices, data partition

    • Cross Platform

      • Linux, Windows, and Mac OS


Benefits from mpeg4 codec
Benefits from MPEG4 codec

  • Support arbitrary sizes of a video stream

    • in contrast to H.261

    • the largest size depends on your video grabber card and camera

  • Less obvious block artifacts


Mpeg4 performance
MPEG4 Performance

  • Typical bit-rate is1Mbps

    • 720x480 (NTSC) with 25 frames/sec and PSNR value is about 40 dB

  • Consistent bit-rate

    • adjusting bit-rate only affects to the quality; not influence the frame-rate

  • Up to 40 CIF, or 10 NTSC video streams.


Deinterlace
Deinterlace

  • Convert interlaced video into progressive one


Efficient color conversion
Efficient Color Conversion

  • VIC didn’t give correct color representation.

  • Efficient Color Conversion

    • Grabber (YUYV) to Encoder (YUV420)

    • Decoder (YUV420) to Display (RGB15/RGB16/RGB24)


Scaling viewing windows
Scaling Viewing Windows

  • Original VIC

    • only support limited sizes of viewing windows

    • based on unrealistic pixel replication method

  • NCHC-VIC

    • scaling viewing windows arbitrarily without too much overhead

    • interpolation by 9 tap FIR filter

    • hardware assisted by Xvideo extension in XFree86

    • full screen mode



Real time video streaming
Real-Time Video Streaming

  • Real-time

    • the compressed data are transferred at a speed that matches the coded video source rate.

  • Latency, Jitter

    • average end-to-end delay

    • delay variation


Error resilience
Error Resilience

  • Error Progratation


Error resilience cont d
Error Resilience (cont’d)

  • Resynchronization marker

    • the data between the error location and the first following resynchronization marker would have to be discarded.

  • Data Partition

    • motion vectors and related syntactic elements are transmitted first, followed by syntactic elements like MB headers, motion vectors, and DCT coefficients.


Minimize latency
Minimize Latency

  • Multithread Encoding

    • Take advantage of symmetric multiple processor architecture

  • Pipeline the latency of transmission and encoding

  • SIMD Instruction Ses

    • Optimized by SSE2/SSE, MMX


Future work
Future Work

  • Support H.264 codec

  • Support MPEG-4 High Efficient AAC (HE-AAC)


Conclusion
Conclusion

  • Project Website:

  • http://vic.nchc.org.tw


Thanks for

your attendance


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