[FFmpeg-trac] #5891(undetermined:new): "-t" not applied to streams when using channelsplit filter

FFmpeg trac at avcodec.org
Fri Oct 14 13:51:09 EEST 2016

#5891: "-t" not applied to streams when using channelsplit filter
             Reporter:  MReedAustin  |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:
  undetermined                       |  unspecified
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
 Summary of the bug:
 I was using volumedetect to check each channel of a file to ensure that
 program start handles were mute, and got misleading readings when the
 incoming audio was split (using channelsplit). I have fixed my code by
 using atrim instead of -t but though the inconsistency was worth

 How to reproduce:
 (Any stereo audio source)
 ffmpeg -ss 149 -i [stereo wav] -filter_complex "[0:0]
 channelsplit=channel_layout=2c [A1] [A2], [A2] anullsink,  [A1]
 volumedetect"  -t 0.96 -vn -f null -
 Results in:
 [Parsed_volumedetect_2 @ 0000000002a463a0] n_samples: '''135634560'''
 [Parsed_volumedetect_2 @ 0000000002a463a0] mean_volume: -25.3 dB
 [Parsed_volumedetect_2 @ 0000000002a463a0] max_volume: -7.7 dB
 [Parsed_volumedetect_2 @ 0000000002a463a0] histogram_7db: 57
 [Parsed_volumedetect_2 @ 0000000002a463a0] histogram_8db: 40871
 [Parsed_volumedetect_2 @ 0000000002a463a0] histogram_9db: 98220

 ffmppeg -ss 149 -i [stereo wav] -filter_complex "[0:0]
 channelsplit=channel_layout=2c [A1] [A2], [A2] anullsink,  [A1]
 atrim=start=0:duration=0.96, volumedetect"  -vn -f null -
 results in:
 [Parsed_volumedetect_3 @ 00000000003400c0] n_samples: '''46080'''
 [Parsed_volumedetect_3 @ 00000000003400c0] mean_volume: -91.0 dB
 [Parsed_volumedetect_3 @ 00000000003400c0] max_volume: -91.0 dB
 [Parsed_volumedetect_3 @ 00000000003400c0] histogram_91db: 46080

 ffmpeg version N-81894-g54220ce
 Zeranoe build

 Patches should be submitted to the ffmpeg-devel mailing list and not this
 bug tracker.

Ticket URL: <https://trac.ffmpeg.org/ticket/5891>
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