1 / 17

Rate-distortion Optimized Mode Selection Based on Multi-channel Realizations

Rate-distortion Optimized Mode Selection Based on Multi-channel Realizations. Markus G ärtner Davide Bertozzi Classroom Presentation 13 th March 2001. Overview. Hybrid Video Coding Proposed Architecture Multi-channel realizations Performance Measurements: Concealment Techniques

rhea
Download Presentation

Rate-distortion Optimized Mode Selection Based on Multi-channel Realizations

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Rate-distortion Optimized Mode Selection Based on Multi-channel Realizations Markus Gärtner Davide Bertozzi Classroom Presentation 13th March 2001

  2. Overview • Hybrid Video Coding • Proposed Architecture • Multi-channel realizations • Performance Measurements: • Concealment Techniques • Number of Channel Realization • Error Propagation • Conclusions Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 13th March 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, 13th March 2001

  4. Proposed Improvements over H.263 • H.263 Hybrid Video Coder: • Error propagation in the decoder loop neglected • Error-free transmission assumed • Threshold based mode selection • Goals of our approach: • Simulation of several channel conditions • Prediction of the error incurred at the receiver • Rate-Distortion optimized mode selection Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 13th March 2001

  5. Multiple Channel Realizations output Coder Frame Buffer Decoder OriginalEncoder nth Channel Realization input Inter Channel n Decoder Conceal-ment & Mode Decision Intra Channel n Decoder Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 13th March 2001

  6. Channel Realizations • Randomly generated error patterns for each channel • Capture different sensitivity of macro-blocks to errors X Channel 1 X Channel 2 X Estimate of the real channel conditions (on the average) Channel n X X Group of blocks (GOB) Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 13th March 2001

  7. Error Concealment X X X X X X • Bit error causes loss of macro block • Synchronization markers before each GOB • Macro block concealment • GOB concealment • Concealment of rest of GOB Erroneous macro-blocks are replaced by respective macro-block of previously reconstructed frame Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 13th March 2001

  8. Distortion Measure For each Macro-block: Channel 1 Channel N Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 13th March 2001

  9. Mode Selection > < Mode Selection Input Frame • Decision takes place for each macro-block  selection table • Computational complexity Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 13th March 2001

  10. Channel Decoder Intra: quantized frame • Inter: previous frame buffer content + difference signal • Intra: quantized frame input Coder Inter: difference signal, motion vectors Foreachchannel: Mode Selection table Reconstructed Frame Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 13th March 2001

  11. Experimental Setup Rate Distortion Quantizer Encoder Frame Buffer Channel Decoder Dequantizer Frame Buffer Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 13th March 2001

  12. Performance Measurement (I) Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 13th March 2001

  13. Performance Measurement (II) Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 13th March 2001

  14. Number of Realizations Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 13th March 2001

  15. Error Propagation (I) • First I-Frame received in error Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 13th March 2001

  16. Error Propagation (II) • First I-Frame received correctly Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 13th March 2001

  17. Conclusions • Suitability for error-prone environments • Better performance than H.263 • Reduction of error propagation • Limitations • Advanced modes of H.263 not considered • Computational complexity • Application for downloadable multimedia • Future work: • Sophisticated channel models • Implementation of advanced features Markus Gärtner, Davide Bertozzi: Robust Video coding Stanford University, 13th March 2001

More Related