Video adaptation in ABR channels with explicit rate feedback control

We propose a video adaptation scheme for video transmission over available bit rate channels. We assume that the ABR channel supports a modified version of the explicit rate feedback control scheme, with which video sources can specify their bandwidth needs by placing a demand value in the resource management cells. Bandwidth is distributed among video connections in proportion to their demands. We investigate issues such as 'How should we adapt the video output rate to the allocated bandwidth.' 'How frequently should we change the demand.' and 'How should we adapt the video output rate to the allocated bandwidth.' Based on our investigation, we propose that the bandwidth demand specification should include both the intrinsic bandwidth requirement of a video source and the current smoothing buffer level. We show that by defining the demand this way, we can limit the worst-case buffering delay at the source. We also show that with an encoder-rate controller, the impact of buffer overflow on the video quality can be reduced by discarding bits from video frames evenly.