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• Unknown V4L2 pixel format equivalent for yuvj420p

  23 mars 2020, par c10ud

  I am trying to pipe a mp4 video located in Videos/video.mp4 to a virtual webcam device located at /dev/video0.

  I tried running :
  ffmpeg -re -i Videos/video.mp4 -map 0:v -f v4l2 /dev/video0
  and I keep getting the following error :

  [video4linux2,v4l2 @ 0x5580cf270100] Unknown V4L2 pixel format equivalent for yuvj420p
  
  Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument
  
  Error initializing output stream 0:0 -- 
  
  Conversion failed!

  Full log :

  ffmpeg version 4.2.2-1+b1 Copyright (c) 2000-2019 the FFmpeg developers
  
    built with gcc 9 (Debian 9.2.1-28)
  
    configuration: --prefix=/usr --extra-version=1+b1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared
  
    libavutil      56. 31.100 / 56. 31.100
  
    libavcodec     58. 54.100 / 58. 54.100
  
    libavformat    58. 29.100 / 58. 29.100
  
    libavdevice    58.  8.100 / 58.  8.100
  
    libavfilter     7. 57.100 /  7. 57.100
  
    libavresample   4.  0.  0 /  4.  0.  0
  
    libswscale      5.  5.100 /  5.  5.100
  
    libswresample   3.  5.100 /  3.  5.100
  
    libpostproc    55.  5.100 / 55.  5.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'Videos/video.mp4':
  
    Metadata:
  
      major_brand     : mp42
  
      minor_version   : 0
  
      compatible_brands: isommp42
  
      creation_time   : 2020-03-23T04:24:01.000000Z
  
      com.android.version: 8.1.0
  
    Duration: 00:01:00.14, start: 0.000000, bitrate: 20048 kb/s
  
      Stream #0:0(eng): Video: h264 (Baseline) (avc1 / 0x31637661), yuvj420p(pc, smpte170m), 1920x1080, 19898 kb/s, SAR 1:1 DAR 16:9, 29.43 fps, 29.58 tbr, 90k tbn, 180k tbc (default)
  
      Metadata:
  
        rotate          : 270
  
        creation_time   : 2020-03-23T04:24:01.000000Z
  
        handler_name    : VideoHandle
  
      Side data:
  
        displaymatrix: rotation of 90.00 degrees
  
      Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 96 kb/s (default)
  
      Metadata:
  
        creation_time   : 2020-03-23T04:24:01.000000Z
  
        handler_name    : SoundHandle
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (h264 (native) -> rawvideo (native))
  
  Press [q] to stop, [?] for help
  
  [video4linux2,v4l2 @ 0x5580cf270100] Unknown V4L2 pixel format equivalent for yuvj420p
  
  Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument
  
  Error initializing output stream 0:0 -- 
  
  Conversion failed!

  The desired result is that the mp4 video is seen by apps that try to view the webcam. I am running this on a desktop without a webcam or video interface, which is why I am using /dev/video0

• Any equivalent to '-c:v copy' for changing container of webm to mp4 video client-side in JS ?

  15 mars 2020, par programmingisphun

  Exploring the Mediarecorder API and really hope to get an mp4 output instead of webm. Prefer to stay client-side to reduce server resources and ffmpeg.js at 17mb doesn’t seem viable for online use.

  Discovered that one can create (Chrome/Firefox) a webm/h.264, which converts without re-encoding to an mp4 using FFMPEG. The resulting file opens fine in Quicktime MacOS (snippet source) :
  ffmpeg -i _inputfile_.webm -c:v copy _outputfile_.mp4

  Whereas this clever hack works to display the video maybe as an mp4 in the browser, but the downloaded file won’t open in Quicktime (just VLC, same for webm) :

  new Blob(recordedBlobs, {type: 'video/mp4'});
  
  video.src = window.URL.createObjectURL(superBuffer);

  Therefore, wondering if there’s another JS hack to do what FFMPEG’s -c:v copy does, but to the blob bytes of the MediaRecorder’s recordedBlobs and give it the same mp4 container that’s accepted by Quicktime/etc ?

  Pastebin of current setup

• showall equivalent ffmpeg flags in VLC ?

  5 décembre 2019, par vagran

  I have a stream which I can play in ffplay using command like this :

  ffplay -flags2 +showall rtsp://localhost:12345/video

  Notice -flags2 +showall option which instructs ffplay not to wait until the first keyframe received before start playing. My video does not have ones (I-frames). It uses encoding scheme which uses only P-frames, so initially video is corrupted, but after several seconds it gradually becomes good. This is not so rare case, actually many popular nowadays DJI drones (e.g. Mavic or Inspire where my video is from, encoded video data is unchanged H.264 stream provided by DJI SDK) have such encoding. So without this flag the playback never starts. The same behaviour is visible in VLC, it connects to RTSP server, receives the stream, but video is not playing probably because of the same reason. Here is a video sample which can be played by ffplay -flags2 +showall inspire.ts.
  Is it possible to specify equivalent option to VLC and be able to play such videos ?