[FFmpeg-user] ffmpeg -f lavfi with -i color / r flag behaves strangely

[gf]

Hi.
Why does the the "r" flag behave differently in the two cases below?
The output for test2.avi shows 25 fps instead of the desired 50 fps. Only
the tbn flag is 50.
ffprobe, however, shows a value of 50 for all timestamps for both avi files.
cheers!


ffmpeg -f lavfi -i color=d=10:r=50 -c copy test1.avi
ffmpeg version N-80117-gdac030d Copyright (c) 2000-2016 the FFmpeg
developers
  built with gcc 5.3.0 (GCC)
  configuration: --enable-gpl --enable-version3 --disable-w32threads
--enable-nvenc --enable-avisynth --enable-bzlib --enable-fontconfig
--enable-frei0r --enable-gnutls --enable-iconv --enable-libass
--enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype
--enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug
--enable-libmfx --enable-libmp3lame --enable-libopencore-amrnb
--enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus
--enable-librtmp --enable-libschroedinger --enable-libsnappy
--enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame
--enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis
--enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264
--enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg
--enable-lzma --enable-decklink --enable-zlib
  libavutil      55. 24.100 / 55. 24.100
  libavcodec     57. 43.100 / 57. 43.100
  libavformat    57. 37.101 / 57. 37.101
  libavdevice    57.  0.101 / 57.  0.101
  libavfilter     6. 46.100 /  6. 46.100
  libswscale      4.  1.100 /  4.  1.100
  libswresample   2.  0.101 /  2.  0.101
  libpostproc    54.  0.100 / 54.  0.100
Input #0, lavfi, from 'color=d=10:r=50':
  Duration: N/A, start: 0.000000, bitrate: N/A
    Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 320x240 [SAR
1:1 DAR 4:3], 50 fps, 50 tbr, 50 tbn
[avi @ 00000000001dd8c0] Using AVStream.codec to pass codec parameters to
muxers is deprecated, use AVStream.codecpar instead.
Output #0, avi, to 'test1.avi':
  Metadata:
    ISFT            : Lavf57.37.101
    Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 320x240 [SAR
1:1 DAR 4:3], q=2-31, 50 fps, 50 tbr, 50 tbn
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
Press [q] to stop, [?] for help
frame=  500 fps=0.0 q=-1.0 Lsize=   56267kB time=00:00:10.00
bitrate=46094.2kbits/s speed= 108x
video:56250kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
muxing overhead: 0.030837%



ffmpeg -f lavfi -i color=d=10 -r 50 -c copy test2.avi
ffmpeg version N-80117-gdac030d Copyright (c) 2000-2016 the FFmpeg
developers
  built with gcc 5.3.0 (GCC)
  configuration: --enable-gpl --enable-version3 --disable-w32threads
--enable-nvenc --enable-avisynth --enable-bzlib --enable-fontconfig
--enable-frei0r --enable-gnutls --enable-iconv --enable-libass
--enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype
--enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug
--enable-libmfx --enable-libmp3lame --enable-libopencore-amrnb
--enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus
--enable-librtmp --enable-libschroedinger --enable-libsnappy
--enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame
--enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis
--enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264
--enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg
--enable-lzma --enable-decklink --enable-zlib
  libavutil      55. 24.100 / 55. 24.100
  libavcodec     57. 43.100 / 57. 43.100
  libavformat    57. 37.101 / 57. 37.101
  libavdevice    57.  0.101 / 57.  0.101
  libavfilter     6. 46.100 /  6. 46.100
  libswscale      4.  1.100 /  4.  1.100
  libswresample   2.  0.101 /  2.  0.101
  libpostproc    54.  0.100 / 54.  0.100
Input #0, lavfi, from 'color=d=10':
  Duration: N/A, start: 0.000000, bitrate: N/A
    Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 320x240 [SAR
1:1 DAR 4:3], 25 fps, 25 tbr, 25 tbn
[avi @ 00000000006508e0] Using AVStream.codec to pass codec parameters to
muxers is deprecated, use AVStream.codecpar instead.
Output #0, avi, to 'test2.avi':
  Metadata:
    ISFT            : Lavf57.37.101
    Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 320x240 [SAR
1:1 DAR 4:3], q=2-31, 25 fps, 25 tbr, 50 tbn
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
Press [q] to stop, [?] for help
frame=  250 fps=0.0 q=-1.0 Lsize=   28142kB time=00:00:09.98
bitrate=23100.4kbits/s speed= 216x
video:28125kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
muxing overhead: 0.061674%