Q.3 Computation of RTP payload size

26.1143GPPIP Multimedia Subsystem (IMS)Media handling and interactionMultimedia telephonyRelease 18TS

When the b=AS bandwidth is computed, it is assumed that the codec is using the highest allowed bit-rate for each frame.

The RTP payload size for the 2 bytes header-full payload format and 1 frame/packet is calculated from the following components:

– 8 bits for the codec mode request (CMR)

– 8 bits for the table of content (ToC)

– N bits for the speech frame (size depends on bit-rate)

– No padding in the end of the RTP payload is needed since each item is already an integer number of octets

The RTP payload size for the 2 bytes header-full payload format and 2 frames/packet is calculated from the following components:

– 8 bits for the codec mode request (CMR)

– 16 bits for the table of content (ToC)

– N bits for the speech frame (size depends on bit-rate)

– No padding in the end of the RTP payload is needed since each item is already an integer number of octets