Note
Access to this page requires authorization. You can try signing in or changing directories.
Access to this page requires authorization. You can try changing directories.
The structure and syntax of this protocol is defined within the RFC for RTP Payload for Redundant Audio Data, as specified in [RFC2198] section 3. This protocol does not cover all audio data redundancy. It is limited to in-band audio communication data. This protocol MUST NOT be used to carry audio data redundancy for audio data such as out-of-band DTMF tones.
The deviation from [RFC2198] is as follows:
[RFC2198] section 2 provides for one or more redundant audio blocks for each RTP payload. This protocol description allows for only one redundant block for every RTP payload. Therefore, each RTP payload MUST NOT contain more than two blocks total: one redundancy block and one primary block.
[RFC2198] section 2 describes the mechanism for including the redundancy information in the RTP packet header. This protocol does not support redundant information in the RTP header. The RTP header MUST NOT contain redundant information. It MUST be made part of a dynamic RTP payload type and negotiate as such during SDP negotiation.
While [RFC2198] section 2 allows for static typing of payload types, systems interoperating with implementation of this protocol MUST negotiate for dynamic redundancy payload type using SDP to enable redundancy as specified in [MS-SDPEXT] section 3.1.5.3.