[FFmpeg-trac] #2325(undetermined:new): MP4 AAC Audio is delayed by 2ms when converted to PCM
FFmpeg
trac at avcodec.org
Wed Mar 6 11:17:58 CET 2013
#2325: MP4 AAC Audio is delayed by 2ms when converted to PCM
-------------------------------------+-------------------------------------
Reporter: brchapman | Owner:
Type: defect | Status: new
Priority: important | Component:
Version: git-master | undetermined
Keywords: aac mov | Resolution:
regression | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
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Comment (by cehoyos):
Replying to [comment:10 brchapman]:
> Also, if I encode test100.mp4 without the aac audio stream (ie with no
audio) and then convert it:
> {{{
> % ffmpeg -i test100_no_aac.mp4 -c:v prores test100_ffmpeg.mov
> }}}
> I don't get the duplicate first frame bug in #2324
You are using a different input file that is cfr, your original sample has
a longer first frame (that needs to be duplicated to get cfr output).
> Based on this I would guess that this would work:
> {{{
> ffmpeg -i test100.mp4 -c:v prores -an test100_ffmpeg.mov
> }}}
> However, it doesn't. The first frame is still duplicated.
Because the timestamps still require a duplication (they do not change
just because you don't encode the audio). Use -vsync 0 to ignore the
timestamps so that no frame duplication happens.
--
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2325#comment:11>
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