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Rate-distortion Optimized Mode Selection Based on Multi-path Channel Simulation

Rate-distortion Optimized Mode Selection Based on Multi-path Channel Simulation. Markus G ärtner Davide Bertozzi Project Proposal Classroom Presentation 6th February 2001. Overview. Hybrid Video Coding Mode selection Previous works Multi-path channel simulation: Architecture

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Rate-distortion Optimized Mode Selection Based on Multi-path Channel Simulation

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  1. Rate-distortion Optimized Mode Selection Based on Multi-path Channel Simulation Markus Gärtner Davide Bertozzi Project Proposal Classroom Presentation 6th February 2001

  2. Overview • Hybrid Video Coding • Mode selection • Previous works • Multi-path channel simulation: • Architecture • Distortion Measure • Expected Results • Workplan Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 6th February 2001

  3. Motion-compensated hybrid coder Mode Control Encoder XOR Decoder Intraframe DCT coder IntraframeDecoder Motion compensated predictor Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 6th February 2001

  4. Inter- / Intra-frame coding • P Frame (inter): • low bit rate, exploits temporal redundancy • sensitivity to error propagation • I Frame (intra): • high bit rate, no temporal dependency • stops error propagation P Frame I Frame Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 6th February 2001

  5. Optimal Mode Selection Intra [%] Foreman 30 20 Salesman 10 4 6 2 Packet error rate [%] Source: Färber, Stuhlmüller, Girod; ICIP 1999 Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 6th February 2001

  6. Previous Approaches • Feedback based methods • Transmission delay limits applicability • Heuristic refresh frequency: periodic intra-coding of: • Whole frames (Turletti-Huitema) • Random blocks (Coté-Kossentini) • Threshold methods (Liao-Villasenor, Färber-Steinbach-Girod) • Content adaptive methods (Haskell-Messerschmitt) • Rate-distortion optimization (Coté-Kossentini) Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 6th February 2001

  7. Block-weighted Distortion Estimate Coté-Kossentini • Block mode chosen according to • Error propagation only beyond one frame • Distortion measure as simple sum of Dq and Dc Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 6th February 2001

  8. Recursive optimal per-pixel Estimate Zhang-Reghunatan-Rose • Distortion is calculated for each pixel • Computational complexity • Holds for inter-pel accuracy only Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 6th February 2001

  9. Our Approach Coder Distortion Estimate Mode Selection Channel 1 Decoder Channel 2 Decoder Channel n Decoder Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 6th February 2001

  10. H.263 Coding Standard frame 16x16 macroblock 8x8 block • I-frame: DCT coding of each 8x8 block • P-frame: DPCM, 8x8 DCT coding of error, one motion vector per macroblock • Mode selection on macro-block basis GOB Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 6th February 2001

  11. Channel Model • Model on macro-block basis X Channel 1 X Channel 2 X “Controlled Randomness” Channel n X X Group of blocks Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 6th February 2001

  12. Distortion Measure R • di comprises any distortion incurred by path i where Our approach: D Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 6th February 2001

  13. Expected Results Average PSNR at decoder Channel modelling Cote-Kossentini H. 263 Error probability Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 6th February 2001

  14. Workplan Final presentation Performance measurements Implementation of Channel models Setup of H.263 Literature Investigation Week 1 Week 2 Week 3 Week 4 Week 5 Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 6th February 2001

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