RTP Payload Types (Q9)
The information in this article applies to:
If there is a static payload type defined for a media, it must be used. Several endpoints currently violate this requirement. Here are the relevant passages in H.225.0v2. 6.2.1: "Payload Type(PT): Only ITU-T payload types such as (0)[PCMU], (8)[PCMA], (9)[G722], and (15)[G728] shall be used. Dynamic payload types exchanged using H.245 signaling shall be used for any ITU-T payload types not listed in Annex B." 6.2.2: "Payload Type(PT): Only ITU-T payload types such as that for H.261 shall be used. Dynamic payload types may be used for H.263 or other ITU-T algorithms for which payload types do not exist." (A payload has been defined for H.263 since this was written, so now the static payload type of 34 must be used for H.263.)
PT encoding audio/video clock rate channels name (A/V) (Hz) (audio) 0 PCMU A 8000 1 8 PCMA A 8000 1 9 G722 A 8000 1 4 G723 A 8000 1 15 G728 A 8000 1 18 G729 A 8000 1 31 H261 V 90000 34 H263 V 90000 96--127 dynamic ? Table 2/Annex B-H.225.0: Payload types (PT) for standard audio and video encodings