Opened 8 years ago
Closed 8 years ago
#5891 closed defect (invalid)
"-t" not applied to streams when using channelsplit filter
Reported by: | Matthew Austin | Owned by: | |
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Priority: | normal | Component: | undetermined |
Version: | unspecified | Keywords: | |
Cc: | Blocked By: | ||
Blocking: | Reproduced by developer: | no | |
Analyzed by developer: | no |
Description
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 highlighting.
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 whereas: 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.
Change History (3)
comment:1 by , 8 years ago
comment:2 by , 8 years ago
This is the expected behaviour: -t
is an output option, it affects the processing after the filters.
Also, using sinks in filter graphs is not very well supported for now. To isolate a channel, you would probably be better off using -af pan
.
comment:3 by , 8 years ago
Resolution: | → invalid |
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Status: | new → closed |
Please provide the actual command line that allows to reproduce the issue together with the complete, uncut console output to make this a valid ticket.