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Figure 5.96: (a) A bitstream switch at a different level of buffer occupancy can cause a decoder to overflow. (b)
Recompression after a switch to return to correct buffer occupancy.
An MPEG-2 switcher will need to monitor the buffer occupancy of its own output to avoid overflow of downstream
decoders. Where this is a possibility the second encoder will have to recompress to reduce the output bit rate
temporarily. In practice there will be a recovery period where the buffer occupancy of the newly selected signal is
matched to that of the previous signal. This is shown in Figure 5.96(b).
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