[FFmpeg-trac] #9523(avcodec:open): segment_times splits at I-frames that are not keyframes

FFmpeg trac at avcodec.org
Tue Nov 30 17:11:47 EET 2021

#9523: segment_times splits at I-frames that are not keyframes
             Reporter:  TurboLed    |                    Owner:  (none)
                 Type:  defect      |                   Status:  open
             Priority:  normal      |                Component:  avcodec
              Version:  git-master  |               Resolution:
             Keywords:              |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |
Comment (by TurboLed):

 Replying to [comment:12 Balling]:
 > So s->key_frame = 1; there does not propogate to ffprobe and more
 keyframes are present in the stream?

 I believe s->key_frame = 1 (AVCodecParserContext::key_frame ->
 h264_parse.c) is not what ffprobe displays as key_frame but rather the
 frame decoding (AVFrame::key_frame -> h264dec.c) which is computed

 I also noted that -f segment is acting as an output filter; so that when
 re-encoding the video (i.e. without -c copy) the splitting occurs on the
 newly generated keyframes from the output. But when splitting a video, you
 usually don't want to re-encode.
Ticket URL: <https://trac.ffmpeg.org/ticket/9523#comment:13>
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