[FFmpeg-trac] #2159(undetermined:closed): FFMPEG not consistently identifying audio tracks and selects audio track with no data

[FFmpeg]

#2159: FFMPEG not consistently identifying audio tracks and selects audio track
with no data
-------------------------------------+-------------------------------------
             Reporter:  ramitbhalla  |                    Owner:
                 Type:  defect       |                   Status:  closed
             Priority:  normal       |                Component:
              Version:  unspecified  |  undetermined
             Keywords:  wtv          |               Resolution:
             Blocking:               |  worksforme
Analyzed by developer:  0            |               Blocked By:
                                     |  Reproduced by developer:  0
-------------------------------------+-------------------------------------

Comment (by cehoyos):

 Replying to [comment:2 ramitbhalla]:
 > Am reopening the ticket, if there is an audio track with no audio / 0
 channels it should NOT report it as stereo, it should report it as 0
 channels:
 >
 >     Stream #0:0[0x75](eng): Audio: mp2 (P[0][0][0] / 0x0050), 48000 Hz,
 stereo, s16p, 256 kb/s (hearing impaired)

 I am not sure I understand: The wtv sample you uploaded contains two audio
 stream, one of them is a mono mp2 stream with id 0x75. Why should FFmepg
 report this stream with 0 channels?

 > You've given a "work around" by using the map function.

 No, I think you misunderstand: Your original command line was "ffmpeg -i
 input -vcodec copy -acodec copy out.ts" and the output of your command
 showed that ffmpeg chose the streams "0:0" and "0:1" as streams to copy.
 My command line is "ffmpeg -i input -map 0:0 -map 0:1 -vcodec copy -acodec
 copy out.ts" just for clarity, to make sure we are discussing the same
 streams. But the output file of my command line is of course binary
 identical no matter if I use -map or not.
 I slightly misunderstood the ticket yesterday but wanted to clarify that
 there is an audio stream 0x75 (and it has more than 0 channels) and that
 audio stream is copied correctly by FFmpeg (I tested A/V sync shortly and
 it works fine afaict).

 > The issue is when applications are parsing the output of ffmpeg they are
 expecting it to have a stereo audio track when actually there isn't one it
 messes everything up.

 FFmpeg warns that the stream parameters may not be correctly, I don't
 think much more can be done.

 > The right output should be a 0 channel audio track like it gives it
 after remuxing to the TS format.

 I don't understand: The stream has one channel and this channel can be
 copied correctly into the transport stream - why should it be shown as
 having 0 channels?

 > Also, if there are no audio channels detected, FFMPEG should NOT select
 the audio track when using the -acodec copy paramater (without the map
 workaround)

 Please look again at my command line - as said I did not use a workaround
 with map, I only specified it to make it clear I am copying the same
 streams as you did.

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2159#comment:6>
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