[FFmpeg-user] recording @ 120fps on mac fails with 'activeVideoMinFrameDuration not supported'

[Roman Puttkammer]

I'm running ffmpeg 3.4 on MacOS Sierra using a USB/UVC camera capable of
120fps at low resolutions (per specs.) At lower frame rates it works well,
but at higher frame rates ffmpeg fails with "An error occurred: The
activeVideoMinFrameDuration passed is not supported by the device.  Use
-activeFormat.videoSupportedFrameRateRanges to discover valid ranges". This
even though the requested frame rate/video size is explicitly listed (by
ffmpeg) as supported.

Any help/suggestions much appreciated! I care little about
resolution/color, but I do need high frame rates.

Thanks.
Roman

###
### List supported modes
Romans-MBP:~ roman$ ffmpeg -f avfoundation -i "0:0"
ffmpeg version 3.4 Copyright (c) 2000-2017 the FFmpeg developers
  built with Apple LLVM version 9.0.0 (clang-900.0.37)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/3.4 --enable-shared
--enable-pthreads --enable-version3 --enable-hardcoded-tables
--enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-gpl
--enable-libmp3lame --enable-libx264 --enable-libxvid --enable-opencl
--enable-videotoolbox --disable-lzma
  libavutil      55. 78.100 / 55. 78.100
  libavcodec     57.107.100 / 57.107.100
  libavformat    57. 83.100 / 57. 83.100
  libavdevice    57. 10.100 / 57. 10.100
  libavfilter     6.107.100 /  6.107.100
  libavresample   3.  7.  0 /  3.  7.  0
  libswscale      4.  8.100 /  4.  8.100
  libswresample   2.  9.100 /  2.  9.100
  libpostproc    54.  7.100 / 54.  7.100
[avfoundation @ 0x7f8b2f800000] Selected framerate (29.970030) is not
supported by the device
[avfoundation @ 0x7f8b2f800000] Supported modes:
[avfoundation @ 0x7f8b2f800000]   320x240@[120.101366 120.101366]fps
[avfoundation @ 0x7f8b2f800000]   640x480@[120.101366 120.101366]fps
[avfoundation @ 0x7f8b2f800000]   800x600@[60.000240 60.000240]fps
[avfoundation @ 0x7f8b2f800000]   1024x768@[30.000030 30.000030]fps
[avfoundation @ 0x7f8b2f800000]   1280x720@[60.000240 60.000240]fps
[avfoundation @ 0x7f8b2f800000]   1280x1024@[30.000030 30.000030]fps
[avfoundation @ 0x7f8b2f800000]   1920x1080@[30.000030 30.000030]fps
[avfoundation @ 0x7f8b2f800000]   320x240@[30.000030 30.000030]fps
[avfoundation @ 0x7f8b2f800000]   640x480@[30.000030 30.000030]fps
[avfoundation @ 0x7f8b2f800000]   800x600@[20.000000 20.000000]fps
[avfoundation @ 0x7f8b2f800000]   1024x768@[6.000002 6.000002]fps
###
### OK -framerate 30
Romans-MBP:~ roman$ ffmpeg -f avfoundation -video_size 320x240 -framerate
30 -pixel_format uyvy422 -i "0:none" out.avi
...

###
### FAILS -framerate 120.101366
Romans-MBP:~ roman$ ffmpeg -f avfoundation -video_size 320x240 -framerate
120.101366 -pixel_format uyvy422 -i "0:none" out.avi
...
[avfoundation @ 0x7f8925002600] An error occurred: The
activeVideoMinFrameDuration passed is not supported by the device.  Use
-activeFormat.videoSupportedFrameRateRanges to discover valid
ranges.0:none: Input/output error
...

###
### FAILS -framerate 120
Romans-MBP:~ roman$ ffmpeg -f avfoundation -video_size 320x240 -framerate
120.101366 -pixel_format uyvy422 -i "0:none" out.avi
...
[avfoundation @ 0x7f95e4000000] Selected framerate (120.000000) is not
supported by the device
...