[FFmpeg-user] decode multiple rtp stream for multichannel usage

[Moritz Barsnick]

Okay, sorry for not seeing that those are two attempts. My bad.

On Tue, Nov 10, 2015 at 21:37:55 +0100, s p wrote:
> $ ffmpeg -i rtpopus.sdp -c:a copy -ar 44100 -f alsa surround71:HD
> > ffmpeg version 2.8.1 Copyright (c) 2000-2015 the FFmpeg developers
[...]
> > Input #0, sdp, from 'rtpopus.sdp':
> >   Metadata:
> >     title           : No Name
> >   Duration: N/A, start: 0.000000, bitrate: N/A
> >     Stream #0:0: Audio: opus, 48000 Hz, stereo, fltp
> > [alsa @ 0x564ee5d982c0] sample format 0x4f505553 is not supported
> > Output #0, alsa, to 'surround71:HD':
> >   Metadata:
> >     title           : No Name
> >     encoder         : Lavf56.40.101
> >     Stream #0:0: Audio: opus, 48000 Hz, stereo
> > Stream mapping:
> >   Stream #0:0 -> #0:0 (copy)
> > Could not write header for output file #0 (incorrect codec parameters ?):
> > Function not implemented

You are trying to copy ("-c:a copy") an opus stream to an alsa device.

ffmpeg complains:
> > [alsa @ 0x564ee5d982c0] sample format 0x4f505553 is not supported
[...]
> > Could not write header for output file #0 (incorrect codec parameters ?):

Does your alsa implementation decode opus by itself? I think not. You
need to let ffmpeg decode opus for you. ffmpeg will probably choose the
correct codec for alsa if you just omit "-c:a ...".

Moritz