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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]


  • 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.
  • 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
    • 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)
  • Project Website:

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