#8436: ffmpeg sets opus audio to stereo in SDP even though it is mono
-------------------------------------+-------------------------------------
Reporter: | Type: defect
rudolfs.bundulis |
Status: new | Priority: minor
Component: | Version:
undetermined | unspecified
Keywords: opus rtsp | Blocked By:
sdp |
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
-------------------------------------+-------------------------------------
Summary of the bug:
ffmpeg sets a=rtpmap:98 opus/48000/2 indicating a stereo track
in RTSP SDP when the source is actually mono.
How to reproduce:
The input file has been attached (Big buck bunny with a mono audio track
that has silence).
{{{
% fmpeg -i mono_opus_sample.mp4 -c:v h264 -c:a opus -strict -2
-rtsp_transport tcp -f rtsp rtsp://localhost:554/app/live
ffmpeg version 4.2.1
built on macOS 10.15
}}}
Here is the output from ffmpeg with -loglevel panic, which shows the
invalid SDP:
{{{
[rtsp @ 0x7fb9ea805800] SDP:
v=0
o=- 0 0 IN IP4 127.0.0.1
s=No Name
c=IN IP4 127.0.0.1
t=0 0
a=tool:libavformat 58.29.100
m=video 0 RTP/AVP 96
a=rtpmap:96 H264/90000
a=fmtp:96 packetization-mode=1; sprop-parameter-
sets=Z2QADazZQUH7DhAAAAMAEAAAAwPA8UKZYA==,aOvjyyLA; profile-level-
id=64000D
a=control:streamid=0
m=audio 0 RTP/AVP 97
b=AS:48
a=rtpmap:97 opus/48000/2 # This track should be mono
a=control:streamid=1
}}}
If not forcing opus (and defaulting to aac), the entry seems correct:
{{{
ffmpeg -i mono_opus_sample.mp4 -c:v h264 -rtsp_transport tcp -f rtsp
rtsp://localhost:554/app/live
}}}
The SDP then is:
{{{
[rtsp @ 0x7fd58c013800] SDP:
v=0
o=- 0 0 IN IP4 127.0.0.1
s=No Name
c=IN IP4 127.0.0.1
t=0 0
a=tool:libavformat 58.29.100
m=video 0 RTP/AVP 96
a=rtpmap:96 H264/90000
a=fmtp:96 packetization-mode=1; sprop-parameter-
sets=Z2QADazZQUH7DhAAAAMAEAAAAwPA8UKZYA==,aOvjyyLA; profile-level-
id=64000D
a=control:streamid=0
m=audio 0 RTP/AVP 97
b=AS:69
a=rtpmap:97 MPEG4-GENERIC/48000/1 # Mono, as it should be
a=fmtp:97 profile-level-id=1;mode=AAC-
hbr;sizelength=13;indexlength=3;indexdeltalength=3; config=118856E500
a=control:streamid=1
}}}
--
Ticket URL: <https://trac.ffmpeg.org/ticket/8436>
FFmpeg <https://ffmpeg.org>
FFmpeg issue tracker
_______________________________________________
FFmpeg-trac mailing list
FFmpeg-trac@avcodec.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-trac
To unsubscribe, visit link above, or email
ffmpeg-trac-requ...@ffmpeg.org with subject "unsubscribe".
