| Summary: | 碩士 === 義守大學 === 資訊工程學系 === 92 === Bit-rate control plays a major role in the video communication system. A well-designed rate control mechanism may realize fine visual quality at given channel rates. This thesis proposes a framework of rate control called Kalman filter rate controller (KFrc), which is compatible with H.263+ standard and includes three encoding phases: the encoding frame rates control, the frame-level bit-allocation and the decision of macroblock-level quantization parameters. The first stage predicts the motion activity of current sub-gop according to the past statistical information and adapts the encoding frame rate to prevent the appearance of object’s motion discontinuity. While detecting buffer overflow, the controller will drop later frames until overflow is relieved. In the picture layer, KFrc detects scene changes and allocates reasonable budget bits to each frame for regularizing coded bit-streams and steadying buffer fullness. The last stage derives the quantization parameter (Qp) of macroblock based on the rate-quantizer (R-Q) model which comprises 31 Qp-characteristic lines. To refine R-Q model further, KFrc employs the prediction and measurement model of Kalman filter for adjusting model parameters. In comparison with TMN8 module, the proposed KFrc can achieve a good balance of spatial-temporal quality and keep the stable buffer status with less computational cost.
|
|---|
