[FFmpeg-trac] #7321(ffprobe:reopened): Sample format for mp2 audio channel is incorrectly determined as fltp rather than s16p

[FFmpeg]

#7321: Sample format for mp2 audio channel is incorrectly determined as fltp
rather than s16p
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             Reporter:  haertel     |                    Owner:
                 Type:  defect      |                   Status:  reopened
             Priority:  normal      |                Component:  ffprobe
              Version:  git-master  |               Resolution:
             Keywords:              |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |
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Changes (by klassikmann):

 * status:  closed => reopened
 * resolution:  invalid =>
 * component:  undetermined => ffprobe


Comment:

 Background:
 The codec mp2 is heavily used in DVB, both cable and SAT. In particular
 DVB-Audio is based on mp2.

 Problem description:
 My DVB SAT receiver streams digital audio to my music server (Pi,
 ArchLinux, RuneAudio, mpd with ffmpeg plugin). After the upgrade of mpd to
 0.20.21 and ffmpeg to 4.0.2 the sample format is detected as fltp instead
 of s16p. Consequence: The ffmpeg plugin invoked by mpd performs a
 (meaningless) conversion from 48000:f:2 to 48000:32:2 producing noise.

 The error can be detected in ffprobe, i.e. it has nothing to do with the
 ffmpeg API.
 ffprobe  -show_format -show_streams hr1.mp2

 Previous (correct) situation:
 ffprobe 3.4.4:
 > Input #0, mp3, from 'hr1.mp2':
 > Duration: 00:00:16.85, start: 0.000000, bitrate: 384 kb/s
 > Stream #0:0: Audio: mp2, 48000 Hz, stereo, '''s16p''', 384 kb/s
 > [STREAM]
 > index=0
 > codec_name=mp2
 > codec_long_name=MP2 (MPEG audio layer 2)
 > profile=unknown
 > codec_type=audio
 > codec_time_base=1/48000
 > codec_tag_string=[0][0][0][0]
 > codec_tag=0x0000
 > sample_fmt='''s16p'''
 > sample_rate=48000
 > channels=2
 > channel_layout=stereo

 Actual (erroneous) situation:
 ffprobe 4.0.2:
 > Input #0, mp3, from 'hr1.mp2':
 > Duration: 00:00:16.85, start: 0.000000, bitrate: 384 kb/s
 > Stream #0:0: Audio: mp2, 48000 Hz, stereo, '''fltp''', 384 kb/s
 > [STREAM]
 > index=0
 > codec_name=mp2
 > codec_long_name=MP2 (MPEG audio layer 2)
 > profile=unknown
 > codec_type=audio
 > codec_time_base=1/48000
 > codec_tag_string=[0][0][0][0]
 > codec_tag=0x0000
 > sample_fmt='''fltp'''
 > sample_rate=48000
 > channels=2
 > channel_layout=stereo

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Ticket URL: <https://trac.ffmpeg.org/ticket/7321#comment:2>
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