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• ffmpeg return black and white image

  16 décembre 2011, par njai

  Video capture device is kworld dvd maker 2 (em2861)
  It returns the image in "black and white" with green line at the bottom of screen ; but when I tested it with webcam, it worked properly.

  Here is 30s video. http://www.youtube.com/watch?v=7q2wFGVwGGI

  How can I convert it to color ?

  [root@localhost ~]# ffmpeg -f video4linux2 -i /dev/video0 -vcodec mpeg4 -y output.mp4
  
  ffmpeg version git-2011-11-05-5fd1a69, Copyright (c) 2000-2011 the FFmpeg developers
  
  built on Nov  5 2011 21:10:52 with gcc 4.4.4 20100726 (Red Hat 4.4.4-13)
  
  configuration: --enable-libx264 --enable-gpl --enable-libvpx
  
  libavutil    51. 23. 0 / 51. 23. 0
  
  libavcodec   53. 27. 0 / 53. 27. 0
  
  libavformat  53. 18. 0 / 53. 18. 0
  
  libavdevice  53.  4. 0 / 53.  4. 0
  
  libavfilter   2. 47. 0 /  2. 47. 0
  
  libswscale    2.  1. 0 /  2.  1. 0
  
  libpostproc  51.  2. 0 / 51.  2. 0
  
  [video4linux2,v4l2 @ 0x2a64780] Estimating duration from bitrate, this may be inaccurate
  
  Input #0, video4linux2,v4l2, from '/dev/video0':
  
  Duration: N/A, start: 1320637788.113946, bitrate: 165888 kb/s
  
  Stream #0:0: Video: rawvideo (YUY2 / 0x32595559), yuyv422, 720x576, 165888 kb/s, 25 tbr, 1000k tbn, 25 tbc
  
  Incompatible pixel format 'yuyv422' for codec 'mpeg4', auto-selecting format 'yuv420p'
  
  [buffer @ 0x2a63920] w:720 h:576 pixfmt:yuyv422 tb:1/1000000 sar:0/1 sws_param:
  
  [buffersink @ 0x2a63cc0] auto-inserting filter 'auto-inserted scale 0' between the filter    'src' and the filter 'out'
  
  [scale @ 0x2a64560] w:720 h:576 fmt:yuyv422 -> w:720 h:576 fmt:yuv420p flags:0x4
  
  Output #0, mp4, to 'output.mp4':
  
  Metadata:
  
  encoder         : Lavf53.18.0
  
  Stream #0:0: Video: mpeg4 ( [0][0][0] / 0x0020), yuv420p, 720x576, q=2-31, 200 kb/s, 25    tbn, 25 tbc
  
  Stream mapping:
  
  Stream #0.0 -> #0.0 (rawvideo -> mpeg4)
  
  Press [q] to stop, [?] for help
  
  frame=  969 fps= 25 q=31.0 Lsize=    1547kB time=00:00:38.76 bitrate= 327.0kbits/s    
  
  video:1538kB audio:0kB global headers:0kB muxing overhead 0.561411%

• swscale : add two spatially stable dithering methods

  23 mars 2014, par Øyvind Kolås

  swscale : add two spatially stable dithering methods
  Both of these dithering methods are from http://pippin.gimp.org/a_dither/ for
  
  GIF they can be considered better than bayer (provides more gray-levels), and
  
  spatial stability - often more than twice as good compression and less visual
  
  flicker than error diffusion methods (the methods also avoids error-shadow
  
  artifacts of diffusion dithers).
  These methods are similar to blue/green noise type dither masks ; but are
  
  simple enough to generate their mask on the fly. They are still research work
  
  in progress ; though more expensive to generate masks (which can be used in a
  
  LUT) like ’void and cluster’ and similar methods will yield superior results
  

  • [DH] doc/scaler.texi
  • [DH] libswscale/options.c
  • [DH] libswscale/output.c
  • [DH] libswscale/swscale_internal.h
  • [DH] libswscale/utils.c

• canvas to ffmpeg - invalid data error

  12 juillet 2017, par nameless

  I’m curently trying to pipe some raw data directly into ffmpeg. The data comes from a canvas. What I do is the following :

  var imageData = ctx.getImageData(0,0,600,600);
  
  var dataArray = imageData.data;
  
  var rgbArray = [];
  
  for (var i = 0; i < dataArray.length; i+=4) {
  
      rgbArray.push([dataArray[i], dataArray[i+1], dataArray[i+2]])
  
  }
  
  
  
  var rgb24Array = rgbArray.map(function(rgbList){
  
      return (rgbList[0] << 16) | (rgbList[1] << 8) | (rgbList[2])
  
  });

  The ffmpegArgs are set like this :

  var ffmpegArgs = [
  
      '-c:v', 'rawvideo' // input container
  
      '-f', 'rawvideo',
  
      '-pix_fmt', 'rgb24', // input pixel format
  
      '-s', '600x600' //input size
  
      '-i', 'pipe:0', // input source
  
      '-format', 'mp4', // output container format
  
      '-c:v', 'libx264', // output video codec
  
      '-b:v', '2m', // output bitrate
  
      'udp://239.255.123.46:1234' // output destination
  
  ];

  So basically, the imageData I get from the canvas has 4 elements for each pixel (rgba), I first filter out the rgb values and then pack them to send them to ffmpeg, I directly pipe them in like ffmpeg.stdin.write(rgb24Array).

  But I get a TypeError: invalid data and I’m not sure why... I also tried to leave data as it is and use rgba as pix_fmt, but same error.

  The stacktrace of the error is :

  TypeError: invalid data
  
     at Socket.write (net.js:617:11)
  
     at null._repeat (....line with ffmpeg.stdin.write() in it)
  
     at wrapper [as_onTimeout] (timers.js:275:11)
  
     at Timer.listonTimeout (timers.js:92:15)

  Does anybody have a idea where the problem could be ?

  Edit :
  changed some things, first, I now use a Uint8Array :

  var imageData = ctx.getImageData(0,0,600,600);
  
              var srcArray = imageData.data;
  
              var dstArray = new Uint8Array(imageData.width * imageData.height * 3);
  
              for(var i = 0, p = 0; i < srcArray.length; i++) { // i++ skips alpha
  
                dstArray[p++] = srcArray[i++];                   // red comp. and incr.
  
                dstArray[p++] = srcArray[i++];                   // green comp. and incr.
  
                dstArray[p++] = srcArray[i++];                   // blue comp. and incr.
  
              }
  
  
  
              ffmpeg.stdin.write(dstArray);

  Also added -video_size parameter to the ffmpegArgs. But still it’s not working and I get the same errors.