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• Pass camera input to ffmpeg

  30 mai 2017, par Sachin Sonone

  I am trying to develop an delphi app which will show a preview of the camera in the delphi form and then send the frames of video as images to the ffmpeg in the stdin of ffmpeg. ffmpeg then broadcast the video to wowza server over rtmp. but fmpeg gives an error ’pipe:0 Bad file descriptor’

      FFMPEG command:
  
      ffmpeg -f image2pipe -i pipe:0  -c:v libx264 -y -report -f flv wowza_url

  I followed this https://msdn.microsoft.com/en-us/library/ms682499(VS.85).aspx article to build the parent app which will open ffmpeg as a child and use FFmpeg’s stdin to pass input

     // Create a pipe for the child process's STDOUT.
  
  Createpipe(STDOut_ReadPipe, STDOut_WritePipe, @Security,0);
  
  
  
    // Ensure the read handle to the pipe for STDOUT is not inherited.
  
  SetHandleInformation(STDOut_ReadPipe,HANDLE_FLAG_INHERIT,0);
  
  
  
  // Create a pipe for the child process's STDIN.
  
  
  
  if (  CreatePipe(STDIn_ReadPipe , STDIn_WritePipe, @Security, 0) = true) then
  
  
  
  
  
  // Ensure the write handle to the pipe for STDIN is not inherited.
  
  
  
  SetHandleInformation(STDIn_WritePipe, HANDLE_FLAG_INHERIT, 0)  ;

  This the code to start ffmpeg process

  FillChar(StartupInfo,Sizeof(StartupInfo),0);
  
  StartupInfo.cb := Sizeof(StartupInfo);
  
  StartupInfo.dwFlags := STARTF_USESTDHANDLES;
  
  
  
  
  
  StartupInfo.wShowWindow := 1;
  
  S := args;
  
  UniqueString(S);
  
  
  
  StartupInfo.hStdError := STDOut_WritePipe;
  
  StartupInfo.hStdOutput := STDOut_WritePipe;
  
  StartupInfo.hStdInput := STDIn_ReadPipe;

  but as soon as program start ffmpeg exits with the error.

  This is the full console log of the ffmpeg

  ffmpeg started on 2017-05-30 at 18:45:36
  
  Report written to "ffmpeg-20170530-184536.log"
  
  Command line:
  
  "ffmpeg.exe" -f image2pipe -i pipe:0 -report -movflags +faststart -tune 
  
  zerolatency -an -pix_fmt yuv420p -preset ultrafast -vcodec libx264 -b:v 250k 
  
  -y -f flv test.flv
  
  ffmpeg version N-85750-ga75ef15 Copyright (c) 2000-2017 the FFmpeg 
  
  developers
  
   built with gcc 6.3.0 (GCC)
  
   configuration: --enable-gpl --enable-version3 --enable-cuda --enable-cuvid 
  
  --enable-d3d11va --enable-dxva2 --enable-libmfx --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-libmp3lame --enable-libopencore-amrnb 
  
    --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --
  
   enable-libopus --enable-librtmp --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-zlib
  
    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. 88.100 /  6. 88.100
  
    libswscale      4.  7.101 /  4.  7.101
  
    libswresample   2.  8.100 /  2.  8.100
  
    libpostproc    54.  6.100 / 54.  6.100
  
    Splitting the commandline.
  
     Reading option '-f' ... matched as option 'f' (force format) with 
  
      argument 'image2pipe'.
  
     Reading option '-i' ... matched as input url with argument 'pipe:0'.
  
    Reading option '-report' ... matched as option 'report' (generate a 
  
    report) with argument '1'.
  
    Reading option '-movflags' ... matched as AVOption 'movflags' with 
  
    argument '+faststart'.
  
    Reading option '-tune' ... matched as AVOption 'tune' with argument 
  
    'zerolatency'.
  
     Reading option '-an' ... matched as option 'an' (disable audio) with 
  
     argument '1'.
  
     Reading option '-pix_fmt' ... matched as option 'pix_fmt' (set pixel 
  
     format) 
  
    with argument 'yuv420p'.
  
   Reading option '-preset' ... matched as AVOption 'preset' with argument 
  
   'ultrafast'.
  
   Reading option '-vcodec' ... matched as option 'vcodec' (force video codec 
  
  ('copy' to copy stream)) with argument 'libx264'.
  
    Reading option '-b:v' ... matched as option 'b' (video bitrate (please use -
  
   b:v)) with argument '250k'.
  
    Reading option '-y' ... matched as option 'y' (overwrite output files) 
  
   with 
  
   argument '1'.
  
   Reading option '-f' ... matched as option 'f' (force format) with argument 
  
  'flv'.
  
  Reading option 'test.flv' ... matched as output url.
  
   Finished splitting the commandline.
  
   Parsing a group of options: global .
  
    Applying option report (generate a report) with argument 1.
  
   Applying option y (overwrite output files) with argument 1.
  
   Successfully parsed a group of options.
  
   Parsing a group of options: input url pipe:0.
  
   Applying option f (force format) with argument image2pipe.
  
    Successfully parsed a group of options.
  
   Opening an input file: pipe:0.
  
   [pipe @ 003bdea0] Setting default whitelist 'crypto'
  
   [AVIOContext @ 03115e60] Statistics: 0 bytes read, 0 seeks
  
   pipe:0: Bad file descriptor'

• strange artifacts in image - where does a frame start ?

  26 mai 2017, par user3387542

  We are live broadcasting a webcam stream. No audio, video only. The current command that works great :

  # Direct replay works well:
  
  ffmpeg -f video4linux2 -r 10 -s 1280x720 -i /dev/video0 -c:v rawvideo -f rawvideo -pix_fmt yuv420p - | \
  
   ffplay -f rawvideo -pixel_format yuv420p -video_size 1280x720 -framerate 10 -

  but as soon as we try to send this data over the network (udp broadcast / gigabit lan) we are getting strange artefacts into the image.

  # server command:
  
  ffmpeg -f video4linux2 -r 10 -s 1280x720 -i /dev/video0 -c:v rawvideo -f rawvideo -pix_fmt yuv420p - | \
  
  socat - UDP-DATAGRAM:10.0.0.255:12345,broadcast
  
  
  
  # client command:
  
  socat -u udp-recv:12345,reuseaddr - | \
  
  ffplay -f rawvideo -pixel_format yuv420p -video_size 1280x720 -framerate 10 -

  Where do these artifacts come from and how to get rid of them ? Does this has something to do with the client not knowing where a certain video frame starts ?

  We have chosen to stream raw video to reduce latency. The final goal would be to apply opencv tools to the video and react live depending on the situation. Which works great, as long as the camera is plugged in directly into this computer. But we need to set it apart and need multiple clients.

  

  The camera used is a Microsoft® LifeCam Studio(TM).

  $ v4l2-ctl -d 0 --list-formats
  
  ioctl: VIDIOC_ENUM_FMT
  
  Index       : 0
  
  Type        : Video Capture
  
  Pixel Format: 'YUYV'
  
  Name        : YUYV 4:2:2
  
  
  
  Index       : 1
  
  Type        : Video Capture
  
  Pixel Format: 'MJPG' (compressed)
  
  Name        : Motion-JPEG
  
  
  
  Index       : 2
  
  Type        : Video Capture
  
  Pixel Format: 'M420'
  
  Name        : YUV 4:2:0 (M420)

  Update

  To narrow down the issue, I tried to split it up into different tasks :

  1.0. Writing the stream to a file :

  ffmpeg -f video4linux2 -r 10 -s 1280x720 -i /dev/video0 -c:v rawvideo -f rawvideo -pix_fmt yuv420p - > ~/deltemp/rawout

  1.1. Reading the file : The result looks great, no artefacts :

  cat ~/deltemp/rawout | ffplay -f rawvideo -pixel_format yuv420p -video_size 1280x720 -framerate 10 -

  2.0 Starting the stream and broadcasting the stream as mentioned in the server command above

  2.1 Writing the UDP stream to a file. And watching the file (artifacts are back again)

  socat -u udp-recv:12345,reuseaddr - > ~/deltemp/rawout
  
  cat ~/deltemp/rawout | ffplay -f rawvideo -pixel_format yuv420p -video_size 1280x720 -framerate 10 -

  As test 1 showed no artifacts and test 2 did, it must be something with udp packet loss.

  Test 3 : Reducing quality to 640x480 did not help either.

• Has anyone used Azure vm's for gpu-accelerated video enc/decoding with FFmpeg/libav ?

  4 mai 2017, par user3776020

  I am trying to use NVIDIA hardware acceleration with FFmpeg/libav on a Microsoft Azure GPU vm (any of the new N-series). I am able to get it working with a comparable AWS vm, but am not having luck with Azure.

  I have a different question posted here detailing the specific problem I’m running into (Trouble with hardware-assisted encoding/decoding via FFmpeg on Azure GPU vm’s (ubuntu 16.04)), but have since realized that the better question to ask is if anyone has been able to achieve it, full-stop.

  If so, would you please share the details of your environment (type of vm, os version, installation commands, etc). Thanks !