For the transmission of video data via different channels like broadcasting, cable networks or data carriers a fixed data transfer rate is given. Usually this is clearly smaller than necessary for uncompressed data. To obtain an acceptable quality the compression procedure must be adapted to the specific requirements of the distribution channel.

Therefore procedures could be used that are continuously working with a constant data transfer rate as MPEG-1 Video with about 150 KByte/s. More complex technologies like MPEG-2 for DVD-Video allow variations in a predefined range. An average transfer rate is given (e.g. 4 MBit/s) that could be exceeded up to a specified maximum (e.g. 10 MBit/s) for encoding of complex contents. To enable a proper hardware design it must be specified how long the exceeding of the average rate may take.

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