[FFmpeg-devel] [PATCH] Change default number of RTSP audio channels to 1

John Wimer j.wimer
Tue Jun 1 11:25:17 CEST 2010


I recently ran into a problem with ffmpeg decoding a mono audio RTP 
stream over, and found that I wasn't the first one with this problem. I 
saw this email from a few years ago but it was never addressed. 

 From reading the RFC that describes the SDP format, which is used by 
RTSP to describe the RTP streams, I see that if no parameters are given, 
the number of channels will be assumed to be one. From 
[http://www.ietf.org/rfc/rfc2327.txt] page 21:

      The general form of an rtpmap attribute is:

      a=rtpmap:<payload type> <encoding name>/<clock rate>[/<encoding

      For audio streams, <encoding parameters> may specify the number of
      audio channels.  This parameter may be omitted if the number of
      channels is one provided no additional parameters are needed.  For
      video streams, no encoding parameters are currently specified.

The attached patch changes the default number of channels to match the 
the rfc.


John Wimer
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