[FFmpeg-user] converting raw video in mkv to y4m looses framerate.

[Andy Furniss]

Original mkv containing raw yuv420p made by ffmpeg some months ago.

I needed to convert to y4m so I do -

ffmpeg -i ducks-2160p60-420.mkv -vcodec copy raw-ducks-2160p60.y4m
ffmpeg version N-74034-gce46627 Copyright (c) 2000-2015 the FFmpeg 
developers
   built with gcc 4.9.2 (GCC)
   configuration: --prefix=/usr --disable-doc --enable-gpl 
--enable-nonfree --enable-opencl --enable-libvpx 
--enable-libschroedinger --enable-libx265 --enable-libdcadec 
--enable-libfdk-aac --enable-libmp3lame --enable-libx264 --enable-x11grab
   libavutil      54. 29.100 / 54. 29.100
   libavcodec     56. 55.100 / 56. 55.100
   libavformat    56. 40.101 / 56. 40.101
   libavdevice    56.  4.100 / 56.  4.100
   libavfilter     5. 29.100 /  5. 29.100
   libswscale      3.  1.101 /  3.  1.101
   libswresample   1.  2.101 /  1.  2.101
   libpostproc    53.  3.100 / 53.  3.100
Input #0, matroska,webm, from 'ducks-2160p60-420.mkv':
   Metadata:
     ENCODER         : Lavf56.40.100
   Duration: 00:00:08.33, start: 0.000000, bitrate: N/A
     Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 
3840x2160, SAR 1:1 DAR 16:9, 60 fps, 60 tbr, 1k tbn, 1k tbc (default)
     Metadata:
       ENCODER         : Lavc56.47.100 rawvideo
Output #0, yuv4mpegpipe, to 'raw-ducks-2160p60.y4m':
   Metadata:
     encoder         : Lavf56.40.101
     Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 
3840x2160 [SAR 1:1 DAR 16:9], q=2-31, 60 fps, 60 tbr, 1k tbn, 1k tbc 
(default)
     Metadata:
       ENCODER         : Lavc56.47.100 rawvideo
Stream mapping:
   Stream #0:0 -> #0:0 (copy)
Press [q] to stop, [?] for help
frame=  500 fps=3.6 q=-1.0 Lsize= 6075003kB time=00:00:08.31 
bitrate=5982979.6kbits/s
video:47kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB 
muxing overhead: 12959906.000000%

The overhead is a bit high! but the framerate looks good.

Anyway players will play the vid but think it's 1000 fps ffmpeg -i below.

I very recently made a different y4m from scratch (images - same way as 
the mkv was made) and all seemed OK with that.
I did note the probesize message but  -probesize 500M -analyzeduration 500M
makes no difference (as expected really given y4m header is small)

ffmpeg -i raw-ducks-2160p60.y4m
ffmpeg version N-74034-gce46627 Copyright (c) 2000-2015 the FFmpeg 
developers
   built with gcc 4.9.2 (GCC)
   configuration: --prefix=/usr --disable-doc --enable-gpl 
--enable-nonfree --enable-opencl --enable-libvpx 
--enable-libschroedinger --enable-libx265 --enable-libdcadec 
--enable-libfdk-aac --enable-libmp3lame --enable-libx264 --enable-x11grab
   libavutil      54. 29.100 / 54. 29.100
   libavcodec     56. 55.100 / 56. 55.100
   libavformat    56. 40.101 / 56. 40.101
   libavdevice    56.  4.100 / 56.  4.100
   libavfilter     5. 29.100 /  5. 29.100
   libswscale      3.  1.101 /  3.  1.101
   libswresample   1.  2.101 /  1.  2.101
   libpostproc    53.  3.100 / 53.  3.100
[yuv4mpegpipe @ 0x2cc1f00] Stream #0: not enough frames to estimate 
rate; consider increasing probesize
Input #0, yuv4mpegpipe, from 'raw-ducks-2160p60.y4m':
   Duration: 00:00:00.50, start: 0.000000, bitrate: N/A
     Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 
3840x2160, SAR 1:1 DAR 16:9, 1k fps, 1k tbr, 1k tbn, 1k tbc