[FFmpeg-trac] #6386(avformat:new): Timebase is written as frame duration for mkv if framerate is unkown

FFmpeg trac at avcodec.org
Thu May 18 12:16:14 EEST 2017


#6386: Timebase is written as frame duration for mkv if framerate is unkown
------------------------------------+------------------------------------
             Reporter:  fthiery     |                    Owner:
                 Type:  defect      |                   Status:  new
             Priority:  minor       |                Component:  avformat
              Version:  git-master  |               Resolution:
             Keywords:  webm mkv    |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |
------------------------------------+------------------------------------

Comment (by fthiery):

 Hi there; applied the patch; now when i ffprobe on the sample, the
 detected framerate seems to be 0 fps

 $ ffprobe -loglevel 56 test_chrome.webm
   Duration: N/A, start: 0.000000, bitrate: N/A
     Stream #0:1(eng), 41, 1/1000: Video: vp8, 1 reference frame,
 yuv420p(progressive), 640x480, 0/1, SAR 1:1 DAR 4:3, 1k tbr, 1k tbn, 1k
 tbc (default)

 Unfortunately, when remuxing with ffmpeg -i test_chrome.webm -c copy
 out.webm, the duration is now correct, but transcoding (ffmpeg -i out.webm
 out.mp4) still results in a 1000 fps output.

 $ ffprobe -loglevel 56 out.webm
   Duration: 00:00:04.98, start: 0.000000, bitrate: 1037 kb/s
     Stream #0:0(eng), 41, 1/1000: Video: vp8, 1 reference frame,
 yuv420p(progressive), 640x480, 0/1, SAR 1:1 DAR 4:3, 1k tbr, 1k tbn, 1k
 tbc (default)

 $ ffmpeg -i out.webm test.mp4
   Metadata:
     encoder         : Lavf57.71.100
     Stream #0:0(eng): Video: h264 (libx264) ([33][0][0][0] / 0x0021),
 yuv420p, 640x480 [SAR 1:1 DAR 4:3], q=-1--1, 1k fps, 16k tbn, 1k tbc
 (default)
     Metadata:
       encoder         : Lavc57.89.100 libx264
     Side data:
       cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
     Stream #0:1(eng): Audio: aac (LC) ([64][0][0][0] / 0x0040), 48000 Hz,
 mono, fltp, 69 kb/s (default)
     Metadata:
       encoder         : Lavc57.89.100 aac
 More than 1000 frames duplicated     227kB time=00:00:01.08
 bitrate=1716.0kbits/s dup=783 drop=0 speed=0.961x

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Ticket URL: <https://trac.ffmpeg.org/ticket/6386#comment:5>
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