[FFmpeg-trac] #786(avformat:new): GXF file frame rate double what it should be for some files.

FFmpeg trac at avcodec.org
Mon Dec 19 17:43:46 CET 2011

#786: GXF file frame rate double what it should be for some files.
             Reporter:  ryaowe      |                    Owner:
                 Type:  defect      |                   Status:  new
             Priority:  normal      |                Component:  avformat
              Version:  git-master  |               Resolution:
             Keywords:              |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |

Comment (by ryaowe):

 That makes sense. But I'm not sure that other case you're talking about
 applies to these files, even though the two sound similar. For this file,
 fields_per_frame=1, which implies that the frame rate really is 60fps. To
 verify this, we set up a small test that reads and decodes each AVFrame
 object, and the decoder emitted an AVPicture for each AVFrame of input.
 We also verified that, when played back at 60fps, the video looks correct,
 and matches up with the audio.

 If the patch still doesn't seem right, can you help me understand that bit
 of code - i.e. what's the "*2" in " {{{ main_timebase.den =
 si->frames_per_second.num * 2; }}} " for exactly? I was just assuming it
 was hardcoding the number of fields per frame (hence my change to take
 fields_per_frame into account instead of hardcoding it), but maybe it's
 for something else?

Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/786#comment:5>
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