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• ffmpeg drops the moov atom when coverting mp4 to ogg, flv, or webm

  31 janvier 2014, par user1370897

  I'm using processor qtfaststart and the gem paperclip-ffmpeg in Rails to convert an mp4 file to either ogg, webm, or flv. However, I haven't had any success converting the mp4 file to these formats for streaming purposes because the moov atom gets dropped (converting mp4 to mp4 keeps its moov atom though*).

  I did a $ qtfaststart -l on the original mp4 file and I get this :

  ftyp (24 bytes)
  
  moov (5691 bytes)
  
  free (399309 bytes)
  
  mdat (12312760 bytes)

  Which shows me that the mp4 file has an moov atom in there. The command that paperclip-ffmpeg is executing is something like this :

  $ ffmpeg -i ~/Movies/VID_20140119_134445.mp4 -acodec libvorbis -ac 2 -ab 96k -ar 44100 -s 640x360 -y ~/tmp/iguana.webm

  However, doing a qtfaststart on the new file (iguana.webm) I get the following :

  $ qtfaststart -l ~/tmp/iguana.webm 
  
  moov atom not found, is this a valid MOV/MP4 file?
  
  Traceback (most recent call last):
  
  File "/usr/local/bin/qtfaststart", line 5, in <module>
  
  pkg_resources.run_script(&#39;qtfaststart==1.8&#39;, &#39;qtfaststart&#39;)
  
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/pkg_resources.py", line 489, in run_script
  
  self.require(requires)[0].run_script(script_name, ns)
  
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/pkg_resources.py", line 1214, in run_script
  
  exec script_code in namespace, namespace
  
  File "/Library/Python/2.7/site-packages/qtfaststart-1.8-py2.7.egg/EGG-INFO/scripts/qtfaststart", line 17, in <module>
  
  
  
  File "build/bdist.macosx-10.9-intel/egg/qtfaststart/command.py", line 44, in run
  
  File "build/bdist.macosx-10.9-intel/egg/qtfaststart/processor.py", line 65, in get_index
  
  File "build/bdist.macosx-10.9-intel/egg/qtfaststart/processor.py", line 106, in _ensure_valid_index
  
  qtfaststart.exceptions.FastStartException
  
  </module></module>

  I've also tried adding the option -movflags faststart to the command ffmpeg but ffmpeg still keeps dropping the moov atom to the output file.

  I'm using Rails 4, paperclip-ffmpeg 1.0.1, ffmpeg 2.1.3 Built on Jan 28 2014. Any help would be greatly appreciated.

• HTTP Header for Duration of a MP4 for HTML 5 video

  9 mars 2014, par Mustafa

  I am trying to stream MP4 video as it is encoded from a webserver. I believe I used the appropriate flags, but it is not working correctly. When I download the video from my stream and open it with VLC, it properly shows the duration. Since a socket is not seekable, I assume it writes the metadata to end ? My Chrome browser always shows 8 seconds duration. The first 8 seconds plays at the normal speed, but afterwards the pause button turns into play button and the video plays very fast, probably as fast as it is recieved. However the audio is played at normal speed. I tried document.getElementById('myVid').duration = 20000 but it is a readonly field.

  I wonder, is there anyway to explicitly state the duration in HTTP headers or in any other way ? I cannot find any documentation about it.

  ffmpeg -i - -vcodec libx264 -acodec libvo_aacenc -ar 44100 -ac 2 -ab 128000 -f mp4 -movflags frag_keyframe+faststart pipe:1 -fflags +genpts -re -profile baseline -level 30 -preset fast

  To close-voters, that thinks it is not programming related, I use it in my own server I coded, and I need to set the duration programatically via JavaScript or setting the HTTP header. I believe it may be related to both ffmpeg or http headers, that's why I posted it here.

  app.get("/video/*", function(req,res){
  
      res.writeHead(200, {
  
          'Content-Type': 'video/mp4',
  
      });
  
      var dir = req.url.split("/").splice(2).join("/");
  
      var buf = new Buffer(dir, 'base64');
  
      var src = buf.toString();
  
  
  
      var Transcoder = require('stream-transcoder');
  
      var stream = fs.createReadStream(src);
  
      // I added my own flags to this module, they are at below:
  
      new Transcoder(stream)
  
          .videoCodec('libx264')
  
          .audioCodec("libvo_aacenc")
  
          .sampleRate(44100)
  
          .channels(2)
  
          .audioBitrate(128 * 1000)
  
          .format('mp4')
  
          .on('finish', function() {
  
              console.log("finished");
  
          })
  
          .stream().pipe(res);
  
  });

  exec function in that stream-transcoder module,

      a.push("-fflags");
  
      a.push("+genpts");
  
      a.push("-re");
  
      a.push("-profile");
  
      a.push("baseline");
  
      a.push("-level");
  
      a.push("30");
  
      a.push("-preset");
  
      a.push("fast");
  
      a.push("-strict");
  
      a.push("experimental");
  
      a.push("-frag_duration");
  
      a.push("" + 2 * (1000 * 1000));
  
      var child = spawn('ffmpeg', a, {
  
          cwd: os.tmpdir()
  
      });

• ffmpeg and python usage

  23 février 2014, par user2063350

  I have an ffmpeg setup on my pc, which streams mp3 with this code :

  ffmpeg -f dshow -i audio="Input device" -c:a libmp3lame -f mpegts udp://192.168.1.2:7777

  Also i have a server and I want my python script to run 24/7 on server and start/stop writing stream to mp3 file every time pc get's turned on/off. I need new file every time pc turns on (use time and date for filename for example) to bypass overwriting. Using python's subprocess module and ffmpeg I can save file on my server like this :

  subprocess.call('ffmpeg -y -i udp://192.168.1.2:7777 -acodec copy output.mp3')

  But I need condition, when to start recording(listen if 7777 port is reciving data or something like that), is it even possible to implement such thing, using python ?
  P.S. Sorry for my bad English.