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• How text align text filter in ffmpeg with multi line text

  2 août 2021, par Konduri Sai Aditya

  how text align center, right , left positions with drawtext with multi line as input.

  


  "Hello \n
world"

  


• Ffmpeg set duration using node-fluent-ffmpeg

  23 mai 2013, par Vprnl

  I'm really new to the world of ffmpeg so please excuses me if this is a stupid queston.

  I'm using the module Node-fluent-ffmpeg to stream a movie and convert it from avi to webm.
  So far so good (it plays the video), but I'm having trouble parsing the duration to the player. My ultimate goal is to be able to skip ahead in the movie. But first the player needs to know how long the video is.

  my code is as followed :

  var stat = fs.statSync(movie);
  
  
  
  var start = 0;
  
  var end = 0;
  
  var range = req.header('Range');
  
  if (range != null) {
  
  start = parseInt(range.slice(range.indexOf('bytes=')+6,
  
    range.indexOf('-')));
  
  end = parseInt(range.slice(range.indexOf('-')+1,
  
    range.length));
  
  }
  
  if (isNaN(end) || end == 0) end = stat.size-1;
  
  if (start > end) return;
  
  
  
  res.writeHead(206, { // NOTE: a partial http response
  
      'Connection':'close',
  
      'Content-Type':'video/webm',
  
      'Content-Length':end - start,
  
      'Content-Range':'bytes '+start+'-'+end+'/'+stat.size,
  
      'Transfer-Encoding':'chunked'
  
  });
  
  
  
  var  proc = new ffmpeg({ source: movie, nolog: true, priority: 1, timeout:15000})
  
      .toFormat('webm')
  
      .withVideoBitrate('1024k')
  
      .addOptions(['-probesize 900000', '-analyzeduration 0', '-bufsize 14000'])
  
      .writeToStream(res, function(retcode, error){
  
      if (!error){
  
          console.log('file has been converted succesfully',retcode);
  
      }else{
  
          console.log('file conversion error',error);
  
      }
  
  });

  I tried to set the header with a start and a end based on this article : http://delog.wordpress.com/2011/04/25/stream-webm-file-to-chrome-using-node-js/

  I also looked in the FFmpeg documentation and found -f duration and -ss.
  But I don't quite know how to convert the byte range to seconds.

  I feel like I'm pretty close to a solution but my inexperience with the subject matter prohibits me from getting it to work. If I'm unclear in any way please let me know. (I have a tendency of explaining things fuzzy.)

  Thanks in advance !

• How to get stream info from opened file in ffmpeg ?

  31 mai 2013, par Srv19

  I am trying to read video file using ffmpeg. I had working code that corresponded to somewhat old version of it, and started to try and upgrade to latest build version, exchanging all those deprecated functions for their actual analogues.

  However i have run into a problem. No streams seem to be retrieved and the load of video stops dead in tracks.

  here is the code i am using :

     // Open video file
  
     if(avformat_open_input(&pFormatCtx, filename.toStdString().c_str(), NULL, NULL)!=0)
  
         return FILE_NOT_OPENED; // Couldn't open file
  
  
  
     // Retrieve stream information
  
     if(avformat_find_stream_info(pFormatCtx,NULL)<0)
  
         return NO_STREAM_INFO; // Couldn't find stream information
  
  
  
     // Dump information about file onto standard error
  
     av_dump_format(pFormatCtx, 0, filename.toStdString().c_str(), false);
  
  
  
     // Find the first video stream
  
     videoStream=-1;
  
     for(unsigned i=0; inb_streams; i++)
  
         if(pFormatCtx->streams[i]->codec->codec_type==ffmpeg::AVMEDIA_TYPE_VIDEO)
  
         {
  
             videoStream=i;
  
             break;
  
         }
  
     if(videoStream==-1)
  
         return OTHER; // Didn't find a video stream
  
  
  
     // Get a pointer to the codec context for the video stream
  
     pCodecCtx=pFormatCtx->streams[videoStream]->codec;
  
  
  
     // Find the decoder for the video stream
  
     pCodec=avcodec_find_decoder(pCodecCtx->codec_id);
  
     if(pCodec==NULL)
  
         return CODEC_NOT_FOUND; // Codec not found
  
  
  
     // Open codec
  
     if(avcodec_open2(pCodecCtx, pCodec,NULL)<0)
  
         return CODEC_NOT_OPENED; // Could not open codec

  The problem arises in the cycle through video streams in ffmpeg::AVFormatContext *pFormatCtx. nb_streams field is 0, and i never actually enter the cycle, and codec is not loaded etc. Strange thing is, av_dump_format gives following output :

  License: GPL version 3 or later
  
  AVCodec version 3606372
  
  AVFormat configuration: --disable-static --enable-shared --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libcaca --enable-libfreetype --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxavs --enable-libxvid --enable-zlib
  
  [asf @ 004e9540] Stream #0: not enough frames to estimate rate; consider increasing probesize
  
  Input #0, asf, from 'C:/Users/Public/Videos/Sample Videos/Wildlife.wmv':
  
    Metadata:
  
      SfOriginalFPS   : 299700
  
      WMFSDKVersion   : 11.0.6001.7000
  
      WMFSDKNeeded    : 0.0.0.0000
  
      comment         : Footage: Small World Productions, Inc; Tourism New Zealand | Producer: Gary F. Spradling | Music: Steve Ball
  
      title           : Wildlife in HD
  
      copyright       : В© 2008 Microsoft Corporation
  
      IsVBR           : 0
  
      DeviceConformanceTemplate: AP@L3
  
    Duration: 00:00:30.09, start: 0.000000, bitrate: 6977 kb/s
  
      Stream #0:0(eng): Audio: wmav2 (a[1][0][0] / 0x0161), 44100 Hz, 2 channels, fltp, 192 kb/s
  
      Stream #0:1(eng): Video: vc1 (Advanced) (WVC1 / 0x31435657), yuv420p, 1280x720, 5942 kb/s, 29.97 tbr, 1k tbn, 1k tbc

  and there are 2 streams, clear as day.

  I am utterly baffled. Please help.