[FFmpeg-trac] #1731(avformat:new): libavformat muxers destroy initial timestamp offsets

FFmpeg trac at avcodec.org
Thu Sep 13 14:01:19 CEST 2012

#1731: libavformat muxers destroy initial timestamp offsets
               Reporter:  saste      |                  Owner:
                   Type:  defect     |                 Status:  new
               Priority:  normal     |              Component:  avformat
                Version:             |               Keywords:  muxer
  unspecified                        |  timestamp flv avi
             Blocked By:             |               Blocking:
Reproduced by developer:  0          |  Analyzed by developer:  0
 Many muxers in libavformat (tested: avi, flv) destory the initial offset.
 This is meant as a feature, but has the effect that remuxing a file will
 destroy the original timestamp information. This is especially annoying in
 case streams from different sources need to be synched.

 How to reproduce:
 ffmpeg -f lavfi -i "aevalsrc=sin(2*PI*400*t)::d=5,asetpts=PTS+10/TB" -y

 then check the packet timestamps with ffprobe -show_packets out.flv.

 A possible workaround:
 ffmpeg -f lavfi -i
 -y out.flv

 (with video the problem can't be easily worked around).

 The behavior with respect to the initial offset could be made configurable
 through some options.

Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/1731>
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