| 摘要 |
<p>A digital video encoder and method for its operation are disclosed. This encoder comprises a frame-layer rate controller that bases a rate-distortion-optimized target bit assignment Tj on an energy estimate for frame j, an average energy estimate for a group of frames, and the desired overall bit rate. If the encoder uses motion compensation, motion bits used for frame j and an average motion bits estimate for a group of frames may also be used by the frame-layer rate controller. Preferably, the desired delay in the system affects how average estimates are computed by the encoder. The frame-layer rate controller of the video encoder above may also utilize buffer protection logic during target bit assignment. This logic adjusts an initial target bit assignment Tj based on the transmission bit rate and desired delay. A primary benefit of the frame-layer rate controller disclosed herein is its basis in a rate-distortion optimal solution to the frame-layer rate control problem. Additional benefits are provided by the explicit consideration of buffer delay during selection of a target bit assignment: rate control robustness allows one controller to be used in a range of delay situations (or even a varying delay situation); and buffer underflow/overflow can be largely eliminated, even in very low delay implementations.</p> |
