[FFmpeg-trac] #2317(undetermined:new): Byte based seeks fail in chained OGG files (with FLAC codec)

FFmpeg trac at avcodec.org
Sat Mar 2 12:43:31 CET 2013


#2317: Byte based seeks fail in chained OGG files (with FLAC codec)
-------------------------------------+-------------------------------------
             Reporter:  gjdfgh       |                    Owner:
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:
              Version:  unspecified  |  undetermined
             Keywords:               |               Resolution:
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  0
-------------------------------------+-------------------------------------

Comment (by gjdfgh):

 You can produce a sample by concatenating two OGG-in-flac files with
 "cat". I don't know how to force byte seeks with ffmpeg. With ffplay, the
 stream appears to be unseekable even with "-bytes 1". However, doing byte
 seeks when using libavformat as library are marked as supported, are
 reported as successful, and lead to strange behavior. Please test it
 yourself with ffplay (possibly by modifying the code to do byte seeks
 properly).

 The behavior I'm experiencing is that libavformat does seem to seek to the
 correct position (I think it even demuxes some audio packets from the new
 position), but then it jumps back. I think it gets confused by the byte
 seek, and tries to "resync" to the "correct" (i.e. previous) file position
 by explicitly issuing a seek.

 Sometimes, it also stops demuxing after printing some errors:
 {{{
 [ogg @ 0x8a8f120]Cannot identify new stream
 [ogg @ 0x8a8f120]failed to create or replace stream
 [ogg @ 0x8a8f120]Cannot identify new stream
 [ogg @ 0x8a8f120]failed to create or replace stream
 }}}

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2317#comment:2>
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