[FFmpeg-trac] #2325(undetermined:open): MP4 AAC Audio is delayed by 2ms when converted to PCM

FFmpeg trac at avcodec.org
Tue Nov 2 18:09:22 EET 2021


#2325: MP4 AAC Audio is delayed by 2ms when converted to PCM
-------------------------------------+-------------------------------------
             Reporter:  BChap        |                    Owner:  (none)
                 Type:  defect       |                   Status:  open
             Priority:  important    |                Component:
                                     |  undetermined
              Version:  git-master   |               Resolution:
             Keywords:  aac mov      |               Blocked By:
  regression                         |
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
Comment (by Balling):

 I just found a mp4/aac file that has crazy 10 116 priming samples!! WOW.
 It is "Advanced Audio Codec with Spectral Band Replication".

 It has media time set to 5058, and you do x2 because it is HC since
 mdhd_TimeScale (?). Nice, just nice, I suppose you should look into that
 too. File Abba - Don't Shut Me Down.mp4 from Tidal. It does have sgpd and
 sbgp though, all good but it has 310720 ms duration which is BS, because
 it is actually (after discarding priming) 8 ms longer than the audio. WTF.
 mdhd.duration is also different after -c copy. Oogh.
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/2325#comment:19>
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