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• Is ffmpeg able to read ArrayBuffer input from stream

  7 juillet 2017, par jAndy

  I want to accomplish the following tasks :

  • Record Video+Audio from any HTML5 (MediaStream) capable browser
  • Send that data via WebSocket as Blob / ArrayBuffer chunks to a server
  • Broadcast that input stream-data to multiple clients

  As it turns out, this brought me into a world of pain. The first task is fairly simple using the HTML5 MediaStream objects alongside WebSockets.

  // ... for simplicity...
  
  navigator.mediaDevices.getUserMedia({ audio: true, video: true }).then(stream => {
  
      let mediaRecorder = new MediaRecorder( stream );
  
      // ...
  
      mediaRecorder.ondataavailable = e => {
  
          webSocket.send( 'newVideoData', e.data ); // configured for binary data
  
      };
  
  });

  Now, I want to receive those data fragments and stream those via nginx vod module, because I guess I want the output stream in HLS or DASH.
  I could write a little nodejs script as backend, which just receives the binary chunks and write them to a file or stream, and just reference it so nginx vod module could possibly read it and create the m3u8 manifest on the fly ?

  I am wondering now,

  • if ffmpeg is able to read that binary data directly (should be webm format), without a man-in-the-middle script, "somehow" ?
  • If not, do I have to write the data down into a file and pass that as input to ffmpeg or can I (should I) pipe the data to a self spawned ffmpeg instance ? (if so, how ?)
  • Do I actually need the nginx server (probably alongside rtmp module) to deliver the output stream as HLS or could I just use ffmpeg to also create a dynamic manifest ?
  • Is the nginx vod module capable of creating a dynamic hls/dash manifest or must the input data be complete beforehand ?
  • Ultimately, am I on the totally wrong track here ? :P

  Actually I just want to create a little video-live-chat demo, without any plugins or 3rd party encoding software, pure browser.

• 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)