Default Media Profiles
The Oracle® Enterprise Session Border Controller (ESBC) contains a set of default media profiles that define characteristics of well-known IANA codecs. You cannot view the default media profiles configurations, but you can override them by configuring identically-named media profile configuration elements.
Transcodable codecs are a subset of the default media profiles, which the ESBC can transcode between.
Preferred Default Payload Type
When the Oracle® Enterprise Session Border Controller (ESBC) adds a codec with a dynamic payload type to SDP, it uses the lowest unused payload number. You can configure a preferred payload type for a dynamic codec by creating an override media profile. The override makes the ESBC use your preferred payload type for insertion into SDP. If you configure a dynamic codec to use a preferred payload type and that payload type is already in use, the codec will still be inserted into SDP, but with the first available dynamic payload type.
For example, suppose you create a media profile for telephone-event with a payload type of 101. If telephone-event is added to SDP, and payload type 101 is already in use in the SDP, the ESBC will use the first available payload type in the 96-127 range when adding telephone-event.
Redefining Codec Packetization Time
You can configure a media profile with a packetization time (ptime) that overrides the default ptime of the codec. Transcoding functions look up and use default ptimes when not specified in offered or answered SDP. The default ptime for most audio codecs is 20ms, but some are 30ms.
To change the default ptime for a codec, you must create a media profile that overwrites the default ptime parameter with your new ptime. When SDP is received with no 'a= ptime' attribute or when adding the codec to egress SDP, the system uses the newly configured ptime.
To set a new default ptime for a media profile, type "ptime=<x>" in the parameters parameter, where <x> is the new default ptime.
mptime Support for Packet Cable
The SDP specification lacks the ability to specify unique packetization times (ptime) per codec when more than one codec is listed in an m= line. The ptime attribute is not related to a specific codec but to the entire m= line. When multiple codecs appear on a single m= line, the PacketCable mptime attribute can specify different packetization times for each codec.
The Oracle® Enterprise Session Border Controller (ESBC) adheres to PKT-SP-NCS1.5-I01-050128 and PKT-SP-EC-MGCP-I06-021127 for processing and generating mptime. The mptime line uses an integer to indicate the ptime for each corresponding codec in the m= line. The dash character, "-", on an mptime line is used for non-packetized codecs, such as CN or telephone-event.
When the ESBC receives an invalid mptime, it is ignored and removed. When a valid mptime is received in the incoming SDP, the ESBC uses its values for the ptimes of each corresponding codec and sends a valid mptime line in the outgoing SDP.
Valid:
m=audio 10000 RTP/AVP 0 96 8
a=mptime:20 - 30
a=rtpmap:96 telephone-event/8000Valid: 'ptime' attribute is ignored
m=audio 10000 RTP/AVP 0 8
a=mptime:20 30
a=ptime:30Invalid: dash cannot be first mptime value
m=audio 10000 RTP/AVP 96 0
a=mptime: - 20When ESBC includes an mptime in an outgoing SDP, it always adds a ptime attribute with the value of the most preferred codec. This is done to increase the interoperability with devices that do not support mptime.