Concepts of Computer Network, Digital Communication, Optimization Techniques are used.

2. Outline
 Introduction
 Background Study
 Problem Statement
 Contribution of Paper
 Sliding-Window Encoding Scheme
 DCT Coefficient Selection
 Simulation Result
 Conclusion
 References

3. Introduction
 Digital video applications have become increasingly popular.
 There are several video standards established for different purposes.
 e.g, MPEG-1, MPEG-2, H.263…
 Delay is an important issue in real-time communication.

4. Background Study
 Streaming video applications
 Video sequences are
 Encoded off-line
 Stored in a server
 Pre-load before playback
 E.g, VOD

5. Problem Statement
 Bit allocation and video quality
 Minimum distortion under the rate constraint

7. Sliding-Window Encoding Scheme
 Use future frames to improve video quality.
 Set window size W to encode video frame.
 frames : i, i+1, …, i+W-1
 let frame i be the current frame
 This proposed encoder better than real-time’s for the
same bitrate.

8. Buffer-size and Pre-loading Time Requirement
 Why need buffer?
 Store the excess bit waiting to be decoded
e.g, bits of future frames
 Why need pre-loading time?
 The delay before playback

9. DCT Coefficient Selection
 Quantize the DCT coefficients
 rate-distortion sense and macroblock level.
 quantizer step-sizes(Q) largely determine the rate-distortion tradeoff.
 There are not optimal for all video sequences by
 limited quantizer selections and
 predetermined run-length codeword.
 The encoder can adjust the quantized coefficient’s level.
 a marginal distortion increase but
 a significant bit-rate reduction.

10. Simulation Result
 Different bitrates:
 32, 64, and 128 kbits/s
 Different types of video sequences:
 large facial movement
 head and shoulder
 camera panning
 Compare with TMN8

12. CONCLUSION
 Better video quality than TMN8 in high motion-activity frames and
scene-change frames.
 Require more buffer size and pre-loading time than TMN8.

13. References
[1] Coding of moving pictures and associated audio for digital storage media at up to about 1.5
Mbit/s, ISO/IEC 11 172, Aug. 1993.
[2] Generic coding of moving pictures and associated audio information, ISO/IEC 13 818, 1995.
[3] Video coding for low bit rate communication, ITU-T Recommendation H.263, March 1996.
[4] G. Cote, B. Erol, M. Gallant, and F. Kossentini, “H.263+: Video coding at low bit rates,” IEEE Trans.
Circuits Syst. Video Technol., vol. 8, pp. 849–866, Nov. 1998.
[5] Test model 5, JTC1/SC29/WG11 coding of moving pictures and associated audio MPEG
96/1260, ISO-IEC/JTC1/SC29/WG11, Mar. 1996.
[6] Video codec test model, TMN8, ITU-T/SG15, Jun. 1997.
[7] Encoding Stored Video For Stremming Applications, IEEE Transactions On Circuits And Systems For
Video Technology, Vol. 11, No. 2, February 2001