Video bandwidth smoothing insufficient

Problem Description

Video bandwidth is inherently very "peaky" as I frames are much larger than P or B frames.  If video packets are sent immediately then bandwidth peaks could potentially lead to buffer overflows in routers.  If the stream of packets is smoothed in order to provide a more constant bandwidth then a high level of jitter is introduced by the smoothing process; provided the playout buffer is larger than the GoP length this jitter can be accommodated.

Symptoms

If the video bandwidth is unsmoothed and buffer levels are insufficient or if the video bandwidth then a high proportion of I frame packets will be dropped.  This will result in severe degradation of quality, and can be identified by the loss rate in I frames being higher than in B or P frames.

If the video bandwidth is smoothed but the playout buffer is too short then a high rate of packet discard will occur within the set-top box - see Playout Buffer problem description. 

Resolution

Consider applying a greater degree of video packet smoothing, or higher capacity network connections.

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