[FFmpeg-trac] #8728(undetermined:open): Misplaced chapters for mp3 files (ID3v2 Chapter Frame Addendum)

FFmpeg trac at avcodec.org
Sun Feb 20 15:35:56 EET 2022


#8728: Misplaced chapters for mp3 files (ID3v2 Chapter Frame Addendum)
-------------------------------------+-------------------------------------
             Reporter:  sandreas     |                    Owner:  (none)
                 Type:  defect       |                   Status:  open
             Priority:  normal       |                Component:
                                     |  undetermined
              Version:  unspecified  |               Resolution:
             Keywords:  chapters,    |               Blocked By:
  mp3, misplaced                     |
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
Changes (by mkver):

 * status:  new => open

Comment:

 1. Your file is gone; you should have uploaded it
 [https://streams.videolan.org/upload/ here] or attached it to this ticket
 in case of small samples.
 2. A quick test of mine shows that the chapters are offset by an amount
 corresponding to encoder delay. In fact, if one has an mp3 file with
 chapters and a xing frame indicating encoder delay, then each round of
 remuxing (without reencoding) offsets the chapters by this encoder delay.
 The demuxer just signals the encoder delay via side data and the
 AVStream's start_time. It is ffmpeg that offsets the chapters to
 (presumably) somehow compensate for this. This is definitely a bug
 (regardless of the missing sample).
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/8728#comment:1>
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