Re: [webrtc-extensions] Question: Does the current SDP setup procedure allow a stereo audio session to be initiated without munging? (#63)

note that `cbr` `useinbandfec` and `usedtx` usage on SDP only expresses that the decoder on the receiver prefers cbr, fec or dtx, but in no way controls what the encoder on any of both sides must use:

```
   cbr:  specifies if the decoder prefers the use of a constant bitrate
      versus a variable bitrate.  Possible values are 1 and 0, where 1
      specifies constant bitrate, and 0 specifies variable bitrate.  If
      no value is specified, the default is 0 (vbr).  When cbr is 1, the
      maximum average bitrate can still change, e.g., to adapt to
      changing network conditions.

   useinbandfec:  specifies that the decoder has the capability to take
      advantage of the Opus in-band FEC.  Possible values are 1 and 0.
      Providing 0 when FEC cannot be used on the receiving side is
      RECOMMENDED.  If no value is specified, useinbandfec is assumed to
      be 0.  This parameter is only a preference, and the receiver MUST
      be able to process packets that include FEC information, even if
      it means the FEC part is discarded.

   usedtx:  specifies if the decoder prefers the use of DTX.  Possible
      values are 1 and 0.  If no value is specified, the default is 0.

```

So the SDP mungling that is allowed by current implementation is just a hack due to the lack of APIs and in no way is backed up by any standard.

-- 
GitHub Notification of comment by murillo128
Please view or discuss this issue at https://github.com/w3c/webrtc-extensions/issues/63#issuecomment-760691609 using your GitHub account


-- 
Sent via github-notify-ml as configured in https://github.com/w3c/github-notify-ml-config

Received on Friday, 15 January 2021 06:49:17 UTC