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I'm trying to capture DNxHR HQX to my SSD. I want HQX because I need the 10-bit color for grading (HQX is a 12-bit codec, but HQ and below are all 8-bit).

8-bit HQ recording is no problem; I consistently get a 1.x+ speed, but 10-bit HQX recording gives me a 0.3x speed and almost instantly fails.

Is there any way to speed up the HQX recording, or lower the quality (I don't need full HQX quality; I just need 10-bit color.)

System info:

8-bit recording is fine

ffmpeg -rtbufsize 1500M -threads 4 -f decklink -i "Intensity Pro 4K@20" -c:a copy -c:v dnxhd -profile:v dnxhr_hq test1123123123.mov

Video stream:

    Stream #0:1: Video: rawvideo (UYVY / 0x59565955), uyvy422, 3840x2160, 3977334 kb/s, 29.97 tbr, 1000k tbn, 1000k tbc

Full output:

E:\>ffmpeg -rtbufsize 1500M -threads 4 -f decklink -i "Intensity Pro 4K@20" -c:a copy -c:v dnxhd -profile:v dnxhr_hq test1123123123.mov
ffmpeg version N-85597-gec07efa700 Copyright (c) 2000-2017 the FFmpeg developers
  built with gcc 6.3.0 (Rev2, Built by MSYS2 project)
  configuration:  --enable-avisynth --enable-libmp3lame --enable-libopus --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-cuda --enable-cuvid --enable-schannel --enable-decklink --enable-fontconfig --enable-frei0r --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libilbc --enable-libmfx --enable-libmodplug --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc --enable-libwavpack --enable-libwebp --enable-libxavs --enable-libxvid --enable-libzimg --enable-openssl --enable-libsnappy --enable-gpl --enable-opencl --enable-opengl --enable-libcdio --enable-libfdk-aac --enable-libkvazaar --enable-librubberband --enable-libssh --enable-libtesseract --enable-libzvbi --enable-chromaprint --enable-libopenh264 --enable-libopenmpt --enable-netcdf --enable-sdl2 --enable-libzmq --extra-cflags=-DLIBTWOLAME_STATIC --extra-cflags=-fopenmp --extra-libs=-lgomp --extra-libs=-lstdc++ --extra-cflags=-DLIBSSH_STATIC --extra-ldflags='-Wl,--allow-multiple-definition' --extra-cflags=-DCACA_STATIC --extra-cflags=-DMODPLUG_STATIC --extra-cflags=-DCHROMAPRINT_NODLL --extra-libs=-lstdc++ --extra-cflags=-DZMQ_STATIC --disable-w32threads --extra-cflags=-DPTW32_STATIC_LIB --extra-libs=-lpthread --extra-libs=-lwsock32 --extra-cflags=-DKVZ_STATIC_LIB --enable-version3 --enable-nonfree --enable-filter=frei0r --disable-debug
  libavutil      55. 61.100 / 55. 61.100
  libavcodec     57. 93.100 / 57. 93.100
  libavformat    57. 72.101 / 57. 72.101
  libavdevice    57.  7.100 / 57.  7.100
  libavfilter     6. 84.101 /  6. 84.101
  libswscale      4.  7.101 /  4.  7.101
  libswresample   2.  8.100 /  2.  8.100
  libpostproc    54.  6.100 / 54.  6.100
[decklink @ 0000017864736440] The @mode syntax is deprecated and will be removed. Please use the -format_code option.
[decklink @ 0000017864736440] Found Decklink mode 3840 x 2160 with rate 29.97
Guessed Channel Layout for Input Stream #0.0 : stereo
Input #0, decklink, from 'Intensity Pro 4K@20':
  Duration: N/A, start: 0.000000, bitrate: 3978870 kb/s
    Stream #0:0: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s
    Stream #0:1: Video: rawvideo (UYVY / 0x59565955), uyvy422, 3840x2160, 3977334 kb/s, 29.97 tbr, 1000k tbn, 1000k tbc
Stream mapping:
  Stream #0:1 -> #0:0 (rawvideo (native) -> dnxhd (native))
  Stream #0:0 -> #0:1 (copy)
Press [q] to stop, [?] for help
Output #0, mov, to 'test1123123123.mov':
  Metadata:
    encoder         : Lavf57.72.101
    Stream #0:0: Video: dnxhd (DNXHR HQ) (AVdh / 0x68645641), yuv422p, 3840x2160, q=2-1024, 200 kb/s, 29.97 fps, 30k tbn, 29.97 tbc
    Metadata:
      encoder         : Lavc57.93.100 dnxhd
    Stream #0:1: Audio: pcm_s16le (sowt / 0x74776F73), 48000 Hz, stereo, s16, 1536 kb/s
frame=  360 fps= 30 q=1.0 Lsize= 1282411kB time=00:00:11.97 bitrate=877018.5kbits/s speed=0.999x
video:1280160kB audio:2246kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.000404%

10-bit recording times out almost instantly

ffmpeg -bm_v210 1 -rtbufsize 1500M -threads 4 -f decklink -i "Intensity Pro 4K@20" -c:a copy -c:v dnxhd -profile:v dnxhr_hqx test1.mov

Video stream:

Stream #0:0: Video: dnxhd (DNXHR HQX) (AVdh / 0x68645641), yuv422p10le, 3840x2160, q=2-1024, 200 kb/s, 29.97 fps, 30k tbn, 29.97 tbc

Full output:

E:\>ffmpeg -bm_v210 1 -rtbufsize 1500M -threads 4 -f decklink -i "Intensity Pro 4K@20" -c:a copy -c:v dnxhd -profile:v dnxhr_hqx test123123121.mov
ffmpeg version N-85597-gec07efa700 Copyright (c) 2000-2017 the FFmpeg developers
  built with gcc 6.3.0 (Rev2, Built by MSYS2 project)
  configuration:  --enable-avisynth --enable-libmp3lame --enable-libopus --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-cuda --enable-cuvid --enable-schannel --enable-decklink --enable-fontconfig --enable-frei0r --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libilbc --enable-libmfx --enable-libmodplug --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc --enable-libwavpack --enable-libwebp --enable-libxavs --enable-libxvid --enable-libzimg --enable-openssl --enable-libsnappy --enable-gpl --enable-opencl --enable-opengl --enable-libcdio --enable-libfdk-aac --enable-libkvazaar --enable-librubberband --enable-libssh --enable-libtesseract --enable-libzvbi --enable-chromaprint --enable-libopenh264 --enable-libopenmpt --enable-netcdf --enable-sdl2 --enable-libzmq --extra-cflags=-DLIBTWOLAME_STATIC --extra-cflags=-fopenmp --extra-libs=-lgomp --extra-libs=-lstdc++ --extra-cflags=-DLIBSSH_STATIC --extra-ldflags='-Wl,--allow-multiple-definition' --extra-cflags=-DCACA_STATIC --extra-cflags=-DMODPLUG_STATIC --extra-cflags=-DCHROMAPRINT_NODLL --extra-libs=-lstdc++ --extra-cflags=-DZMQ_STATIC --disable-w32threads --extra-cflags=-DPTW32_STATIC_LIB --extra-libs=-lpthread --extra-libs=-lwsock32 --extra-cflags=-DKVZ_STATIC_LIB --enable-version3 --enable-nonfree --enable-filter=frei0r --disable-debug
  libavutil      55. 61.100 / 55. 61.100
  libavcodec     57. 93.100 / 57. 93.100
  libavformat    57. 72.101 / 57. 72.101
  libavdevice    57.  7.100 / 57.  7.100
  libavfilter     6. 84.101 /  6. 84.101
  libswscale      4.  7.101 /  4.  7.101
  libswresample   2.  8.100 /  2.  8.100
  libpostproc    54.  6.100 / 54.  6.100
[decklink @ 0000019b57ed6540] The @mode syntax is deprecated and will be removed. Please use the -format_code option.
[decklink @ 0000019b57ed6540] Found Decklink mode 3840 x 2160 with rate 29.97
Guessed Channel Layout for Input Stream #0.0 : stereo
Input #0, decklink, from 'Intensity Pro 4K@20':
  Duration: N/A, start: 0.000000, bitrate: 5304648 kb/s
    Stream #0:0: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s
    Stream #0:1: Video: v210 (V210 / 0x30313256), yuv422p10le, 3840x2160, 5303112 kb/s, 29.97 tbr, 1000k tbn, 1000k tbc
Stream mapping:
  Stream #0:1 -> #0:0 (v210 (native) -> dnxhd (native))
  Stream #0:0 -> #0:1 (copy)
Press [q] to stop, [?] for help
Output #0, mov, to 'test123123121.mov':
  Metadata:
    encoder         : Lavf57.72.101
    Stream #0:0: Video: dnxhd (DNXHR HQX) (AVdh / 0x68645641), yuv422p10le, 3840x2160, q=2-1024, 200 kb/s, 29.97 fps, 30k tbn, 29.97 tbc
    Metadata:
      encoder         : Lavc57.93.100 dnxhd
    Stream #0:1: Audio: pcm_s16le (sowt / 0x74776F73), 48000 Hz, stereo, s16, 1536 kb/s
[decklink @ 0000019b57ed6540] Decklink input buffer overrun!itrate=874616.0kbits/s speed=0.313x
    Last message repeated 27 times
[decklink @ 0000019b57ed6540] Decklink input buffer overrun!itrate=874609.5kbits/s speed=0.319x
    Last message repeated 27 times
[decklink @ 0000019b57ed6540] Decklink input buffer overrun!itrate=874605.2kbits/s speed=0.324x
    Last message repeated 27 times
[decklink @ 0000019b57ed6540] Decklink input buffer overrun!itrate=896389.6kbits/s speed=0.327x
    Last message repeated 4 times
frame=   42 fps= 10 q=1.0 Lsize=  149610kB time=00:00:01.36 bitrate=895868.2kbits/s speed=0.327x
video:149352kB audio:257kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.001212%
[decklink @ 0000019b57ed6540] Decklink input buffer overrun!
    Last message repeated 1 times

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