Dialogic DIALOGIC MULTIMEDIA SOFTWARE FOR ADVANCEDTCA RELEASE 1.0 Supported RTP Payload Format

This feature is only supported when using the Session Initiation Protocol (SIP). None of the available Session Description Protocol (SDP) options are currently supported through Global Call (that is, direct first-party call control). The options are only available using third-party call control (3PCC), where the application is responsible for interpreting received SDP text strings and for constructing all outbound SDP text strings.

Dialogic® IP Media Library API Support

The bit rate can be controlled using a new media type in the IPM_MEDIA structure. The Dialogic® IP Media Library API allows the application to provide a preferred bit rate and a rule to determine how changes in the received CMR value control the transmitted bit rate.

Preferred bit rate

The preferred bit rate is specified by setting the eMediaType in the IPM_MEDIA structure to MEDIATYPE_AUDIO_REMOTE_CODER_INFO and setting the CoderInfo.eCoderType to the desired transmit bit rate.

CMR value

The transmitted CMR value is specified by setting the eMediaType in the IPM_MEDIA structure to MEDIATYPE_AUDIO_LOCAL_CODER_INFO and setting the CoderInfo.eCoderType to the desired CMR value.

The CMR rules are specified by a new media type called

MEDIATYPE_AUDIO_REMOTE_CODER_OPTIONS_INFO. A new field AudioCoderOptionsInfo (of type IPM_AUDIO_CODER_OPTIONS_INFO) has been added to the IPM_MEDIA union. The CMR control is implemented by allowing the host application to specify one of two rules.

•The first rule, “CMR Tracking,” indicates that the transmit bit rate should follow the CMR value in the received packet.

•The second rule, “CMR Limit,” indicates that the transmit bit rate should follow the CMR value in the received packet with a maximum value specified by the preferred bit rate.

With both CMR rules, it is necessary to specify a preferred rate to avoid the specific case of determining what rate to transmit at before the first CMR value is received. The software will transmit at the preferred rate before the first packet is received or when a CMR value of 15 (don't care) is received from the opposite side.

The CMR rules are set in the AudioCoderOptionsInfo.unCoderOptions field by ORing in either CODER_OPT_AMR_CMR_TRACK or CODER_OPT_AMR_CMR_LIMIT.

Specifying a CMR rule is mandatory and the rules are mutually exclusive.

Note: The CMR rules are not used by the MEDIATYPE_AUDIO_LOCAL_CODER_OPTIONS_INFO eMediaTypes.

Supported RTP Payload Format

AMR supports two different formats for the RTP payload:

•“Bandwidth efficient,” to minimize the amount of network bandwidth.

Dialogic® Multimedia Software for ATCA Release 1.0 Release Update, Rev 06 — January 23, 2008	33
Dialogic Corporation