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Design of Packet Video Receivers for Best Effort Networks - Playout Policies

Delay diagram The transmission of real-time streams over best-effort networks has been an interesting research area for over a decade. An important objective of the research community has been to devise methods that cope with the variations of the network delay -- also called delay jitter -- that are an inherent characteristic of best-effort networks. Jitter destroys the temporal relationships between periodically transmitted media units that constitute a real-time media stream, thus hindering the comprehension of the stream. Playout adaptation algorithms undertake the labor of the temporal reconstruction of the stream, which is sometimes referred to as the restoration of its intrastream synchronization quality.

We have studied the problem of designing a packet video receiver for best effort networks under the influence of delay jitter. Our main results has been an optimized playout policy that monitors the current number of frames in the playout buffer and the level of network jitter and regulates the presentation duration of frames accordingly. The system tries to avoid long-lasting disruptions, such buffer underflow and overflows, and instead substitute them with smaller more frequent disruptions that may be unnoticed due to human perceptual limitations in the detection of motion. The produced results have been recorded in the following publications: