AudioCodes Mediant 4000 SBC User Manual page 391

User's Manual
Parameter
Transcoding Mode
transcoding-mode
[IpProfile_TranscodingMode]
Extension Coders Group
sbc-ext-coders-group-name
[IpProfile_SBCExtensionCod
ersGroupName]
Allowed Audio Coders
allowed-audio-coders-group-
name
[IpProfile_SBCAllowedAudio
CodersGroupName]
Allowed Coders Mode
sbc-allowed-coders-mode
[IpProfile_SBCAllowedCoder
sMode]
Version 7.2
Defines the transcoding mode (media negotiation) for the SIP entity
associated with the IP Profile.

[0] Only if Required = (Default) Transcoding is done only when
necessary. Many of the media settings (such as gain control) are
not implemented on the voice stream. The device forwards RTP
packets transparently (RTP-to-RTP), without processing them.

[1] Force = Transcoding is always done on the outgoing leg. The
device interworks the media for the SIP entity (as both legs have
different media capabilities), by implementing DSP transcoding.
This enables the device to receive capabilities that are not
negotiated between the SIP entities. For example, it can enforce
gain control to use voice transcoding even though both legs have
negotiated without the device's intervention (such as extension
coders).
For more information on extension coders and transcoding, see Coder
Transcoding on page 429,
Note:

To implement transcoding, you must configure the number of
required DSP channels for transcoding (using the MediaChannels
parameter). Each transcoding session uses two DSP resources.

The corresponding global parameter is TranscodingMode.
Assigns a Coder Group used for extension coders, added to the SDP
offer in the outgoing leg for the SIP entity associated with the IP
Profile. This is used when transcoding is required between two IP
entities (i.e., the SDP answer from one doesn't include any coder
included in the offer previously sent by the other).
For more information on extension coders and transcoding, see Coder
Transcoding on page 429,
To configure Coder Groups, see Configuring Coder Groups on page
375.
Assigns an Allowed Audio Coders Group, which defines audio (voice)
coders that can be used for the SIP entity associated with the IP
Profile.
To configure Allowed Audio Coders Groups, see Configuring Allowed
Audio Coder Groups on page 380. For a description of the Allowed
Coders feature, see ''Restricting Coders'' on page 428.
Defines the mode of the Allowed Coders feature for the SIP entity
associated with the IP Profile.

[0] Restriction = In the incoming SDP offer, the device uses only
Allowed coders; the rest are removed from the SDP offer (i.e., only
coders common between those in the received SDP offer and the
Allowed coders are used). If an Extension Coders Group is also
assigned (using the 'Extension Coders Group' parameter, above),
these coders are added to the SDP offer if they also appear in
Allowed coders.

[1] Preference = The device re-arranges the priority (order) of the
coders in the incoming SDP offer according to their order of
appearance in the Allowed Audio Coders Group or Allowed Video
Coders Group. The coders in the original SDP offer are listed after
the Allowed coders.

[2] Restriction and Preference = Performs both Restriction and
391
19. Coders and Profiles
Description
Mediant 4000 SBC