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8.2.3. Usage in Declarative Session Descriptions

8.2.3. Usage in Declarative Session Descriptions​

When H.264 over RTP is offered with SDP in a declarative style, as in Real Time Streaming Protocol (RTSP) [27] or Session Announcement Protocol (SAP) [28], the following considerations are necessary.

  • All parameters capable of indicating both stream properties and receiver capabilities are used to indicate only stream properties. For example, in this case, the parameter profile-level-id declares only the values used by the stream, not the capabilities for receiving streams. The result of this is that the following interpretation of the parameters MUST be used:

Declaring actual configuration or stream properties:

  • profile-level-id - packetization-mode - sprop-interleaving-depth - sprop-deint-buf-req - sprop-max-don-diff - sprop-init-buf-time

Out-of-band transporting of parameter sets:

  • sprop-parameter-sets - sprop-level-parameter-sets

Not usable (when present, they SHOULD be ignored):

  • max-mbps - max-smbps - max-fs - max-cpb - max-dpb - max-br - max-recv-level - redundant-pic-cap - max-rcmd-nalu-size - deint-buf-cap - sar-understood - sar-supported - in-band-parameter-sets - level-asymmetry-allowed - use-level-src-parameter-sets

  • A receiver of the SDP is required to support all parameters and values of the parameters provided; otherwise, the receiver MUST reject (RTSP) or not participate in (SAP) the session. It falls on the creator of the session to use values that are expected to be supported by the receiving application.

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