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• ffmpeg throws error while converting wav to flac

  24 août 2017, par user3815252

  I am working on a research project and it requires me to first record audios from browser (using getuserMedia) and save them in a wav format. My code looks like this :

  navigator.mediaDevices.getUserMedia({ audio: true }).then(stream => {
  
          const chunks = [];
  
          const recorder = new MediaRecorder(stream);
  
          recorder.ondataavailable = e => {
  
              chunks.push(e.data);
  
              if (recorder.state == 'inactive') {
  
                  $scope.blob = new Blob(chunks, { type: 'audio/wav' });
  
                  $scope.file = new File([$scope.blob], "myFile.wav", {type: 'audio/wav', lastModified: Date.now()});
  
  
  
                  $scope.blobUrl = URL.createObjectURL($scope.blob);
  
                  createAudioElement($scope.blobUrl);
  
              }
  
          };
  
          recorder.start(1000);
  
          $scope.stop = function() {
  
              recorder.stop();    
  
          };
  
  
  
      }).catch(console.error);

  After saving $scope.file on filesystem, I convert it to flac format using ffmpeg utility ([https://www.ffmpeg.org/).

  Now my problem is the ffmpeg tool sometimes gives me error saying that this file cannot be recognized as wav file. The exact output of ffmpeg tool is :

    ffmpeg-user: Wav to Flac conversion: Invalid data found when processing input
  
  
  
    ffmpeg version 3.3.3 Copyright (c) 2000-2017 the FFmpeg developers 
  
    built with Apple LLVM version 7.0.2 (clang-700.1.81) 
  
    configuration: --prefix=/usr/local/Cellar/ffmpeg/3.3.3 --enable-shared 
  
    --enable-pthreads --enable-gpl --enable-version3 
  
    --enable-hardcoded-tables 
  
    --enable-avresample --cc=clang --host-cflags= --host-ldflags= 
  
    --enable-libmp3lame --enable-libx264 --enable-libxvid --enable-opencl 
  
  
  
    --disable-lzma --enable-vda 
  
    libavutil      55. 58.100 / 55. 58.100 
  
    libavcodec     57. 89.100 / 57. 89.100 
  
    libavformat    57. 71.100 / 57. 71.100 
  
    libavdevice    57.  6.100 / 57.  6.100 
  
    libavfilter     6. 82.100 /  6. 82.100 
  
    libavresample   3.  5.  0 /  3.  5.  0 
  
    libswscale      4.  6.100 /  4.  6.100 
  
    libswresample   2.  7.100 /  2.  7.100 
  
    libpostproc    54.  5.100 / 54.  5.100 

  Does anyone know why am I getting this error ?

• Merging multiple videos in a template/layout with Python FFMPEG ?

  14 janvier 2021, par J. M. Arnold

  I'm currently trying to edit videos with the Python library of FFMPEG. I'm working with multiple file formats, precisely .mp4, .png and text inputs (.txt). The goal is to embed the different video files within a "layout" - for demonstration purposes I tried to design an example picture :

  


  

  


  The output is supposed to be a 1920x1080 .mp4 file with the following Elements :

  


  

  • Element 3 is the video itself (due to it being a mobile phone screen recording, it's about the size displayed there)

  


  • Element 1 and 2 are the "boarders", i.e. static pictures (?)

  


  • Element 4 represents a regularly changing text - input through the python script (probably be read from a .txt file)

  


  • Element 5 portrays a .png, .svg or alike ; in general a "picture" in the broad sense.

  


  


  What I'm trying to achieve is to create a sort of template file in which I "just" need to input the different .mp4 and .png files, as well as the text and in the end I'll receive a .mp4 file whereas my Python script functions as the navigator sending the data packages to FFMPEG to process the video itself.

  


  I dug into the FFMPEG library as well as the python-specific repository and wasn't able to find such an option. There were lots of articles explaining the usage of "channel layouts" (though these don't seem to fit my need).

  


  In case anyone wants to try on the same versions :

  


  

  • python --version :
Python 3.7.3

  


  • pip show ffmpeg : Version : 1.4 (it's the most recent ; on an off-topic note : It's not obligatory to use FFMPEG, I'd prefer using this library though if it doesn't offer the functionality I'm looking for, I'd highly appreciate if someone suggested something else)

  


  


• Converting a binary stream to an mpegts stream

  22 décembre 2018, par John Kim

  I’m trying to create a livestream web app using NodeJS. The code I currently have emits a raw binary stream from the webcam on the client using socket IO and the node server receives this raw data. Using fluent-ffmpeg, I want to encode this binary stream into mpegts and send it to an RTMP server in real time, without creating any intermediary files. Could I somehow convert the binary stream into a webm stream and pipe that stream into an mpegts encoder in one ffmpeg command ?

  My relevant frontend client code :

  navigator.mediaDevices.getUserMedia(constraints).then(function(stream) {
  
      socket.emit('config_rtmpDestination',url);
  
      socket.emit('start','start');
  
      mediaRecorder = new MediaRecorder(stream);
  
      mediaRecorder.start(2000);
  
  
  
      mediaRecorder.onstop = function(e) {
  
          stream.stop();
  
      }
  
  
  
      mediaRecorder.ondataavailable = function(e) {
  
        socket.emit("binarystream",e.data);
  
      }
  
  }).catch(function(err) {
  
      console.log('The following error occured: ' + err);
  
      show_output('Local getUserMedia ERROR:'+err);
  
  });

  Relevant NodeJS server code :

  socket.on('binarystream',function(m){
  
      feedStream(m);
  
  });
  
  
  
  socket.on('start',function(m){
  
      ...
  
      var ops=[
  
          '-vcodec', socket._vcodec,'-i','-',
  
          '-c:v', 'libx264', '-preset', 'veryfast', '-tune', 'zerolatency',
  
          '-an', '-bufsize', '1000',
  
          '-f', 'mpegts', socket._rtmpDestination
  
      ];
  
      ffmpeg_process=spawn('ffmpeg', ops);
  
      feedStream=function(data){
  
          ffmpeg_process.stdin.write(data);
  
      }
  
      ...
  
  }

  The above code of course doesn’t work, I get these errors on ffmpeg :

  Error while decoding stream #0:1: Invalid data found when processing input
  
  [NULL @ 000001b15e67bd80] Invalid sync code 61f192.
  
  [libvpx @ 000001b15e6c5000] Failed to decode frame: Bitstream not supported by this decoder

  because I’m trying to convert raw binary data into mpegts.