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• Unknown V4L2 pixel format equivalent for yuva420p with ffmpeg and v4l2loopback

  7 février 2019, par Kim

  I am trying to use filter_complex from ffmpeg to stich several video input together into one output.

  I use v4l2loopback to create a virtual video device :

  sudo modprobe v4l2loopback video_nr=90

  In this example, i first try with only one camera :

  v4l2-ctl --device=/dev/video0 --info gives the following output :

  Driver Info (not using libv4l2):
  
          Driver name   : uvcvideo
  
          Card type     : HD USB Camera
  
          Bus info      : usb-0000:00:14.0-13.2
  
          Driver version: 4.10.17
  
          Capabilities  : 0x84200001
  
                  Video Capture
  
                  Streaming
  
                  Extended Pix Format
  
                  Device Capabilities
  
          Device Caps   : 0x04200001
  
                  Video Capture
  
                  Streaming
  
                  Extended Pix Format
  
  Priority: 2
  
  Video input : 0 (Camera 1: ok)
  
  Format Video Capture:
  
          Width/Height      : 640/480
  
          Pixel Format      : 'YUYV'
  
          Field             : None
  
          Bytes per Line    : 1280
  
          Size Image        : 614400
  
          Colorspace        : sRGB
  
          Transfer Function : Default
  
          YCbCr Encoding    : Default
  
          Quantization      : Default
  
          Flags             :
  
  Crop Capability Video Capture:
  
          Bounds      : Left 0, Top 0, Width 640, Height 480
  
          Default     : Left 0, Top 0, Width 640, Height 480
  
          Pixel Aspect: 1/1
  
  Selection: crop_default, Left 0, Top 0, Width 640, Height 480
  
  Selection: crop_bounds, Left 0, Top 0, Width 640, Height 480
  
  Streaming Parameters Video Capture:
  
          Capabilities     : timeperframe
  
          Frames per second: 30.000 (30/1)
  
          Read buffers     : 0
  
                       brightness (int)    : min=0 max=15 step=1 default=8 value=8
  
                         contrast (int)    : min=0 max=15 step=1 default=8 value=8
  
                       saturation (int)    : min=0 max=15 step=1 default=7 value=7
  
                              hue (int)    : min=-10 max=10 step=1 default=0value=0
  
   white_balance_temperature_auto (bool)   : default=1 value=1
  
                            gamma (int)    : min=1 max=10 step=1 default=7 value=7
  
                             gain (int)    : min=0 max=0 step=0 default=0 value=0
  
             power_line_frequency (menu)   : min=0 max=2 default=2 value=2
  
        white_balance_temperature (int)    : min=2800 max=6500 step=1 default=2800 value=2800 flags=inactive
  
                        sharpness (int)    : min=0 max=15 step=1 default=6 value=6
  
           backlight_compensation (int)    : min=0 max=1 step=1 default=0 value=0
  
                    exposure_auto (menu)   : min=0 max=3 default=3 value=3
  
                exposure_absolute (int)    : min=4 max=5000 step=1 default=625 value=625 flags=inactive
  
                   focus_absolute (int)    : min=0 max=21 step=1 default=16 value=16 flags=inactive
  
                       focus_auto (bool)   : default=1 value=1

  Then i use this command to ouput /dev/video0 to /dev/video90 on the left side with a specific resolution :

  ffmpeg -loglevel verbose -y \
  
    -f v4l2 -thread_queue_size 512 -i /dev/video0 \
  
    -filter_complex "nullsrc=size=960x240 [base]; \
  
            [0:v] format=pix_fmts=yuva420p, setpts=PTS-STARTPTS, scale=320x240 [left]; \
  
            [base][left] overlay=shortest=1" \
  
    -f v4l2 /dev/video90

  Which results in the following error :

  [v4l2 @ 0x55fa67d02f60] Unknown V4L2 pixel format equivalent for yuva420p
  
  Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument
  
  Error initializing output stream 0:0 --
  
  Conversion failed!

  Full logs :

  ffmpeg version 3.4.4-1~16.04.york0 Copyright (c) 2000-2018 the FFmpeg developers
  
    built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.10) 20160609
  
    configuration: --prefix=/usr --extra-version='1~16.04.york0' --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --disable-stripping --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-librsvg --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libopencv --enable-libx264 --enable-shared
  
    WARNING: library configuration mismatch
  
    avcodec     configuration: --prefix=/usr --extra-version='1~16.04.york0'--toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --disable-stripping --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-librsvg --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libopencv --enable-libx264 --enable-shared --enable-version3 --disable-doc --disable-programs --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libtesseract --enable-libvo_amrwbenc
  
    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
  
  [video4linux2,v4l2 @ 0x55fa67cfca00] fd:5 capabilities:84200001
  
  [video4linux2,v4l2 @ 0x55fa67cfca00] Querying the device for the current frame size
  
  [video4linux2,v4l2 @ 0x55fa67cfca00] Setting frame size to 640x480
  
  Input #0, video4linux2,v4l2, from '/dev/video0':
  
    Duration: N/A, start: 273229.829138, bitrate: 147456 kb/s
  
      Stream #0:0: Video: rawvideo, 1 reference frame (YUY2 / 0x32595559), yuyv422, 640x480, 147456 kb/s, 30 fps, 30 tbr, 1000k tbn, 1000k tbc
  
  [Parsed_nullsrc_0 @ 0x55fa67d00680] size:960x240 rate:25/1 duration:-1.000000 sar:1/1
  
  [Parsed_scale_3 @ 0x55fa67d02240] w:320 h:240 flags:'bilinear' interl:0
  
  Stream mapping:
  
    Stream #0:0 (rawvideo) -> format
  
    overlay -> Stream #0:0 (rawvideo)
  
  Press [q] to stop, [?] for help
  
  [Parsed_nullsrc_0 @ 0x55fa67cfc760] size:960x240 rate:25/1 duration:-1.000000 sar:1/1
  
  [Parsed_scale_3 @ 0x55fa67d055c0] w:320 h:240 flags:'bilinear' interl:0
  
  [graph 0 input from stream 0:0 @ 0x55fa67d06a40] w:640 h:480 pixfmt:yuyv422 tb:1/1000000 fr:30/1 sar:0/1 sws_param:flags=2
  
  [auto_scaler_0 @ 0x55fa67d05d80] w:iw h:ih flags:'bilinear' interl:0
  
  [Parsed_format_1 @ 0x55fa67d04360] auto-inserting filter 'auto_scaler_0' between the filter 'graph 0 input from stream 0:0' and the filter 'Parsed_format_1'
  
  [auto_scaler_0 @ 0x55fa67d05d80] w:640 h:480 fmt:yuyv422 sar:0/1 -> w:640 h:480 fmt:yuva420p sar:0/1 flags:0x2
  
  [Parsed_format_1 @ 0x55fa67d04360] TB:0.000001 FRAME_RATE:30.000000 SAMPLE_RATE:nan
  
  [Parsed_scale_3 @ 0x55fa67d055c0] w:640 h:480 fmt:yuva420p sar:0/1 -> w:320 h:240 fmt:yuva420p sar:0/1 flags:0x2
  
  [Parsed_overlay_4 @ 0x55fa67d05e80] main w:960 h:240 fmt:yuva420p overlay w:320 h:240 fmt:yuva420p
  
  [Parsed_overlay_4 @ 0x55fa67d05e80] [framesync @ 0x55fa67d05fa8] Selected 1/1000000 time base
  
  [Parsed_overlay_4 @ 0x55fa67d05e80] [framesync @ 0x55fa67d05fa8] Sync level 2
  
  [v4l2 @ 0x55fa67d02f60] Unknown V4L2 pixel format equivalent for yuva420p
  
  Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument
  
  Error initializing output stream 0:0 --
  
  Conversion failed!

  What I tried and didn’t work :

  • use -f h264 for the output, which ends in a av_interleaved_write_frame(): Invalid argument error

• Is there a Mac OS X equivalent of Windows' named pipe

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