R: R: R: [Asterisk-Users] How to force G729

Chris A. Icide chris at netgeeks.net
Thu Jun 24 09:52:45 MST 2004

On 07:01 AM 6/24/2004, Rich Adamson wrote:
 >Now I better understand what you're trying to do.
 >I'm not a programmer, but I'm fairly certain that you can't dynamically
 >change codec preference within asterisk on a per call basis. However,
 >just as soon as this gets posted, someone will likely jump all over
 >that statement and post a way to do it.
 >I don't think its and incoming vs outgoing issue. For each outgoing call,
 >an rtp session is established between * and the gateway. That rtp session
 >goes through a codec negotiation process that automatically selects a
 >compatible codec based on what's common, and, when multiple choices
 >are available, some other decision making process (transcode time, quality
 >or something) that you probably don't have control over on a per call
 >So, my guess is you're not going to be able to do what you want.

It sounds like what you are looking for is an Asterisk-wide (or perhaps 
channel-specific) preserve_codec option.  Where preserve_codec=1 means that 
asterisk tries to preserve the originating codec if at all possible, and 
preserve_codec=0 lets asterisk freely choose any codec per whatever 
algorithm it chooses.  As far as I know, this option doesn't exist, but 
depending upon the need, perhaps someone should issue a feature 
request.  It seems like this might be an easy feature to add.


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