Hello,
Let’s say Alice calls an Asterisk instance from a SIP phone. The dialplan processing Alice’s call includes an Answer() followed by a Playback() statement.
How Asterisk negociates a codec with Alice’s phone ?
Can the format of the audio file played by Playback() app, influence the selected codec ?
Wher can I read doc about codec selection when one call leg is an Asterisk app (ie not a SIP phone) ?
Best regards
If the recording exists in more than one format, Asterisk chooses the format that can be converted at the lowest processing cost. I’m not sure if if tries all the codecs offered by the caller, or only the first choice one. I have a suspicion it is the first choice one.
I believe Asterisk’s SDP offer is sent before this selection is made, even if the call was unanswered when Playback was called.
I believe dialplan variables can be used to change the first choice codec.
I also think SDP/codec selection is done when Answer() application is run.
Thanks for replying