Opened 11 months ago

Last modified 8 days ago

#10314 new defect

FFmpeg concat introduces gaps, even encoding to wav; does not occur with mpg123.

Reported by: Karen Róbertsdóttir Owned by:
Priority: normal Component: ffmpeg
Version: 5.0.2 Keywords: gaps, mp3, wav, mpg123
Cc: Blocked By:
Blocking: Reproduced by developer: no
Analyzed by developer: no

Description

mpg123 -w out_mpg123.wav 160k_75_80_15-8_v5_B/00015[5678]*

vs.

echo -n > list.txt; for i in 160k_75_80_15-8_v5_B/00015[5678]*.mp3; do echo "file '$i'" >> list.txt; done; ffmpeg -y -f concat -safe 0 -i list.txt -c copy out_ffmpeg.wav

See the attached waveform to see the gap, and the source files to recreate. My suspicion is that ffmpeg concat is not respecting the stated file length, and is instead just writing out whole blocks even if the block extends out beyond the end of the file.

Attachments (5)

Screenshot_20230410_141046.png (43.2 KB ) - added by Karen Róbertsdóttir 11 months ago.
Waveform comparing the mpg123 (no added gap) .wav file with the ffmpeg (added gap) .wav file.
000155_00019.mp3 (102.1 KB ) - added by Karen Róbertsdóttir 11 months ago.
First sound sample
000156_00019.mp3 (102.1 KB ) - added by Karen Róbertsdóttir 11 months ago.
Second sound sample
000157_00019.mp3 (102.1 KB ) - added by Karen Róbertsdóttir 11 months ago.
Third sound sample
000158_00019.mp3 (102.1 KB ) - added by Karen Róbertsdóttir 11 months ago.
Fourth sound sample

Download all attachments as: .zip

Change History (8)

by Karen Róbertsdóttir, 11 months ago

Waveform comparing the mpg123 (no added gap) .wav file with the ffmpeg (added gap) .wav file.

by Karen Róbertsdóttir, 11 months ago

Attachment: 000155_00019.mp3 added

First sound sample

by Karen Róbertsdóttir, 11 months ago

Attachment: 000156_00019.mp3 added

Second sound sample

by Karen Róbertsdóttir, 11 months ago

Attachment: 000157_00019.mp3 added

Third sound sample

by Karen Róbertsdóttir, 11 months ago

Attachment: 000158_00019.mp3 added

Fourth sound sample

comment:1 by Michael Niedermayer, 9 days ago

Blocking: Have to use mpg123 as a workaround; ruined the timings on my current project, have to redo.

the "blocking" field should not be filled with random text

comment:2 by Karen Róbertsdóttir, 8 days ago

That's not "random text", that's describing the work that the bug blocks and whether or not there's a workaround that lets the project continue (TL/DR, there is, but it requires 3rd party software). And seriously, your important takeaway from the bug report was... what information was put in what fields in the submission form?

comment:3 by Gyan, 8 days ago

The primary consumers of bug reports are FFmpeg developers. All these metadata fields are meant to be in relation to the FFmpeg project, not the bug reporter.

Last edited 8 days ago by Gyan (previous) (diff)
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