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• Recording a webpage stream with multiple requests using PhantomJS & ffmpeg to /dev/stdout leads to ffmpeg error

  2 septembre 2016, par Allisson Ferreira

  First of all, sorry for my english.

  I’m in a quest for days. I’ve researched everywhere and I couldn’t find an answer to my problem.

  I’m using Nodejs, Phantomjs and ffmpeg in this scenary :

  • An user enters the site, login with facebook and he can ask for a video with his name and some random photos (gathered by /me/ & sent via JSON POST) ;
  • Node receive the user data, creates a child process (PhantomJS + ffmpeg) and awaits for a response to send the video URL to the user.

  When I run a single instance of this request, everything is working fine. BUT, when two or more users make the request, only one video is sent and the others process end up in a ffmpeg stream error.

  I think the reason is that all the ffmpeg processes are using the same place (/dev/stdout). Since one process is already using it, the others enters in a "can’t access" error. But it is a assumption, I don’t know how /dev/stdout really works.

  Here are my codes. (I have removed some lines and renamed some variables for better understanding, sorry for any mistake)

  index.js :

  var generateVideo = 'phantomjs phantom.js '+videoID+' '+userID+' | ffmpeg -vcodec png -f image2pipe -r 30 -i - -pix_fmt yuv420p public/videos/'+userID+'/'+videoID+'.mp4 -y';
  
  
  
  childProcess.exec(generateVideo, function(err, stdout, stderr) {
  
      var json    = {};
  
      json.video  = '/videos/'+userID+'/'+videoID+'.mp4';
  
      res.send(json);
  
  });

  phantom.js :

  var page            = require('webpage').create();
  
  page.viewportSize   = { width: 1366, height: 768 };
  
  page.settings.resourceTimeout = 10000;
  
  
  
  var args            = require('system').args;
  
  var videoID         = args[1];
  
  var userID          = args[2];
  
  
  
  page.open('http://localhost:3000/recordvideo/'+videoID, 'post', function(status){
  
      var frame       = 0;
  
      var target_fps  = 30;
  
      var maxframes   = page.evaluate(function () {
  
                          return getTotalDurationInSeconds();
  
                      }) * target_fps;
  
  
  
      setInterval(function(){
  
          page.render('/dev/stdout', { format: "png" });
  
          if( frame >= maxframes ){
  
              phantom.exit();
  
          }
  
          frame++;
  
      }, (1000 / target_fps));
  
  });

  And the error :

  [Error: Command failed: /bin/sh -c phantomjs phantom.js XXXXXXXX XXXXXXXX | ffmpeg -vcodec png -f image2pipe -r 30 -i - -pix_fmt yuv420p public/videos/XXXXXXXX/XXXXXXXX.mp4 -y
  
  www-0 ffmpeg version N-80901-gfebc862 Copyright (c) 2000-2016 the FFmpeg developers
  
  www-0   built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04.3)
  
  www-0   configuration: --extra-libs=-ldl --prefix=/opt/ffmpeg --mandir=/usr/share/man --enable-avresample --disable-debug --enable-nonfree --enable-gpl --enable-version3 --enable-libopencore-amrnb --enable-libopencore-amrwb --disable-decoder=amrnb --disable-decoder=amrwb --enable-libpulse --enable-libfreetype --enable-gnutls --enable-libx264 --enable-libx265 --enable-libfdk-aac --enable-libvorbis --enable-libmp3lame --enable-libopus --enable-libvpx --enable-libspeex --enable-libass --enable-avisynth --enable-libsoxr --enable-libxvid --enable-libvidstab
  
  www-0   libavutil      55. 28.100 / 55. 28.100
  
  www-0   libavcodec     57. 48.101 / 57. 48.101
  
  www-0   libavformat    57. 41.100 / 57. 41.100
  
  www-0   libavdevice    57.  0.102 / 57.  0.102
  
  www-0   libavfilter     6. 47.100 /  6. 47.100
  
  www-0   libavresample   3.  0.  0 /  3.  0.  0
  
  www-0   libswscale      4.  1.100 /  4.  1.100
  
  www-0   libswresample   2.  1.100 /  2.  1.100
  
  www-0   libpostproc    54.  0.100 / 54.  0.100
  
  www-0 [png @ 0x3d7c4a0] Invalid PNG signature 0x46726F6D20506861.
  
  www-0 [image2pipe @ 0x3d72780] decoding for stream 0 failed
  
  www-0 [image2pipe @ 0x3d72780] Could not find codec parameters for stream 0 (Video: png, none(pc)): unspecified size
  
  www-0 Consider increasing the value for the 'analyzeduration' and 'probesize' options
  
  www-0 Input #0, image2pipe, from 'pipe:':
  
  www-0   Duration: N/A, bitrate: N/A
  
  www-0     Stream #0:0: Video: png, none(pc), 30 tbr, 30 tbn, 30 tbc
  
  www-0 [buffer @ 0x3d81540] Unable to parse option value "0x0" as image size
  
  www-0 [buffer @ 0x3d81540] Unable to parse option value "-1" as pixel format
  
  www-0 [buffer @ 0x3d81540] Unable to parse option value "0x0" as image size
  
  www-0 [buffer @ 0x3d81540] Error setting option video_size to value 0x0.
  
  www-0 [graph 0 input from stream 0:0 @ 0x3d72600] Error applying options to the filter.
  
  www-0 Error opening filters!
  
  www-0 ]

  I really hope that I can find an answer here !
  And sorry if there already is an answer for this. But I researched for days.

  Thank you in advance !

• Why ffmpeg rotates video ?

  15 septembre 2016, par hasanghaforian

  I use this code in a bash script to create GIF images from video files :

  ffmpeg -y -ss 3 -t 4 -i $vid \
  
   -vf fps=10,scale=320:-1:flags=lanczos,palettegen palette.png
  
  
  
  ffmpeg -ss 3 -t 4 -i $vid -i palette.png -filter_complex \
  
   "fps=10,scale=320:-1:flags=lanczos[x];[x][1:v]paletteuse" ../gifs/"$i".gif

  But some GIF images are rotated ! While their thumbnails which is created by OS is not rotated. How I can solve this problem ?

  Update :

  Here you can see outputs of commands :

  Generating palette :

  ffmpeg version N-79139-gde1a0d4 Copyright (c) 2000-2016 the FFmpeg developers
  
    ...
  
  Input #0, 
  
  ...
  
      Metadata:
  
        rotate          : 90
  
        creation_time   : ...
  
        handler_name    : VideoHandle
  
        encoder         :                                
  
      Side data:
  
        displaymatrix: rotation of -90.00 degrees
  
      ...

  Creating GIF using the palette :

  Input #0, 
  
  ...
  
      Metadata:
  
        rotate          : 90
  
        creation_time   : 2012-01-01 07:47:56
  
        handler_name    : VideoHandle
  
        encoder         :                                
  
      Side data:
  
        displaymatrix: rotation of -90.00 degrees
  
      ...

• Convert swf to mp4

  28 septembre 2016, par Aleksey Kontsevich

  This answer had not helped : Convert compressed swf to mp4, trying to convert swf file.

  ffmpeg output :

  $ ffmpeg -i GTDS_demo_new.swf GTDS_demo_new.mp4
  
  ffmpeg version 2.8.6-1ubuntu2 Copyright (c) 2000-2016 the FFmpeg developers
  
    built with gcc 5.3.1 (Ubuntu 5.3.1-11ubuntu1) 20160311
  
    configuration: --prefix=/usr --extra-version=1ubuntu2 --build-suffix=-ffmpeg --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --cc=cc --cxx=g++ --enable-gpl --enable-shared --disable-stripping --disable-decoder=libopenjpeg --disable-decoder=libschroedinger --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-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --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-libxvid --enable-libzvbi --enable-openal --enable-opengl --enable-x11grab --enable-libdc1394 --enable-libiec61883 --enable-libzmq --enable-frei0r --enable-libx264 --enable-libopencv
  
    WARNING: library configuration mismatch
  
    avcodec     configuration: --prefix=/usr --extra-version=1ubuntu2 --build-suffix=-ffmpeg --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --cc=cc --cxx=g++ --enable-gpl --enable-shared --disable-stripping --disable-decoder=libopenjpeg --disable-decoder=libschroedinger --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-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --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-libxvid --enable-libzvbi --enable-openal --enable-opengl --enable-x11grab --enable-libdc1394 --enable-libiec61883 --enable-libzmq --enable-frei0r --enable-libx264 --enable-libopencv --enable-version3 --disable-doc --disable-programs --disable-avdevice --disable-avfilter --disable-avformat --disable-avresample --disable-postproc --disable-swscale --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libvo_aacenc --enable-libvo_amrwbenc
  
    libavutil      54. 31.100 / 54. 31.100
  
    libavcodec     56. 60.100 / 56. 60.100
  
    libavformat    56. 40.101 / 56. 40.101
  
    libavdevice    56.  4.100 / 56.  4.100
  
    libavfilter     5. 40.101 /  5. 40.101
  
    libavresample   2.  1.  0 /  2.  1.  0
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  2.101 /  1.  2.101
  
    libpostproc    53.  3.100 / 53.  3.100
  
  [swf @ 0x21cd1e0] Could not find codec parameters for stream 1 (Video: none, none): unknown codec
  
  Consider increasing the value for the 'analyzeduration' and 'probesize' options
  
  Input #0, swf, from 'GTDS_demo_new.swf':
  
    Duration: N/A, start: 0.000000, bitrate: N/A
  
      Stream #0:0: Audio: mp3, 44100 Hz, mono, s16p, 64 kb/s
  
      Stream #0:1: Video: none, none, 12 fps, 12 tbr, 12 tbn
  
  File 'GTDS_demo_new.mp4' already exists. Overwrite ? [y/N] y
  
  No decoder for stream #0:1, filtering impossible
  
  Error opening filters!

  Splitting with dump-gnash also does not help : get sound without video after ffmpeg (this answer : http://stackoverflow.com/a/21023110/630169)