#9708 closed defect (duplicate)
.aac files produced by ffmpeg miss duration
Reported by: | Jozef Chutka | Owned by: | |
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Priority: | normal | Component: | undetermined |
Version: | unspecified | Keywords: | aac duration |
Cc: | Jozef Chutka | Blocked By: | |
Blocking: | Reproduced by developer: | no | |
Analyzed by developer: | no |
Description (last modified by )
When doing some audio manipulation with ffmpeg, the .aac output miss duration information. I wonder if this is a container design issue or ffmpeg implementation bug.
ffmpeg -filter_complex amovie=source.wav,adelay=4000 -c:a aac -y out.aac ffmpeg -i out.aac [aac @ 0000027a343998c0] Estimating duration from bitrate, this may be inaccurate Input #0, aac, from 'output/out.aac': Duration: 00:02:31.21, bitrate: 1 kb/s
.m4a extension (which I see being used on https://trac.ffmpeg.org/wiki/Encode/AAC) seems ok
ffmpeg -filter_complex amovie=source.wav,adelay=4000 -c:a aac -y out.m4a ffmpeg -i out.aac Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'output/out.m4a': Metadata: major_brand : M4A minor_version : 512 compatible_brands: M4A isomiso2 encoder : Lavf59.17.101 Duration: 00:00:06.62, start: 0.000000, bitrate: 33 kb/s
A combination of m4a format for aac encoder doesnt seem appropriate:
ffmpeg -filter_complex amovie=source.wav,adelay=4000 -c:a aac -f m4a -y out.aac [NULL @ 00000237e631db40] Requested output format 'm4a' is not a suitable output format
mp4 format in .aac seems ok:
ffmpeg -filter_complex amovie=source.wav,adelay=4000 -c:a aac -f mp4 -y out.aac ffmpeg -i out.aac Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'output/out.aac': Metadata: major_brand : isom minor_version : 512 compatible_brands: isomiso2mp41 encoder : Lavf59.17.101 Duration: 00:00:06.62, start: 0.000000, bitrate: 33 kb/s
But I am not sure its ok to have mp4 inside .aac file.
Marking it as a defect b/c I believe that .aac with its default container should provide duration information.
Using ffmpeg version 2022-02-07-git-04cc7a5548-full_build-www.gyan.dev
Attachments (1)
Change History (5)
by , 3 years ago
Attachment: | source.wav added |
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comment:1 by , 3 years ago
Description: | modified (diff) |
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comment:2 by , 3 years ago
comment:3 by , 3 years ago
Hi @Balling, thanks for loooking into it.
Is there any workaround to resolve the duration?
I just tried ffmpeg -i out.aac -c copy -y fix.aac
which produces the same output, same invalid duration...
comment:4 by , 3 years ago
Resolution: | → duplicate |
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Status: | new → closed |
Duration is correct, as written by the encoder. We are just reading it wrong ON MONO files, and you are writing mono here, Mediainfo is correctly reading them. I am closing this as duplicate of #5448.
But I am not sure its ok to have mp4 inside .aac file.
The file you got must be renamed to mp4 as it is mp4. Also aac is just .adts, not aac. There is not such thing as ".aac".
-f m4a is invalid. The way you do it is add out.m4a that will automocatically add -brand and all the needed stuff in the header.
There is such a bug already. #5448 There is no way to know the actual duration and what part of it is garbage in the start and the end.