[FFmpeg-trac] #9140(ffmpeg:reopened): aac gapless fail

FFmpeg trac at avcodec.org
Fri Sep 17 07:58:35 EEST 2021

#9140: aac gapless fail
             Reporter:  Guy Sivey    |                    Owner:  (none)
                 Type:  defect       |                   Status:  reopened
             Priority:  normal       |                Component:  ffmpeg
              Version:  unspecified  |               Resolution:
             Keywords:  aac gapless  |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
Comment (by Balling):

 >identify if my files follow this standard

 Any command ffplay, ffmpeg will show metadata iTunSMPB. As to how to edit,
 I recommend Audacity, of course. Just see what amount of samples you
 should delete from both sides.

 >some kind of industry standard for making mp3/m4a(aac) gapless work

 Yes, you can use an editlist to remove 256 samples (that is what is
 written BTW, not timestamp) for eac3 sound, but you will have to remove 11
 ms from the end for eac3. Same for aac. As for concat, it should work with
 longer editlist. There is also a way to use PTS (presentation timestamps)
 for mkv or TS yet those will not be perefctly 256, for example, so IMHO,

 >that it is Apple who is out of line

 Apple came first! ISO standard for AAC using edts + sgpd atoms and LAME
 way for gapless mp3 came after that.
Ticket URL: <https://trac.ffmpeg.org/ticket/9140#comment:9>
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