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• Webm video files recorded on Chrome Mobile cannot be converted to MP4

  7 juillet 2022, par Tobias Kristensen

  I have a website where I record the user's webcam via the MediaRecorder API.
The video stream is created with navigator.mediaDevices.getUserMedia() :

  


  // Create stream
const cameraStream = await navigator.mediaDevices.getUserMedia({ video: 
  { 
    aspectRatio: 1/1, 
    facingMode: 'user',
    width: { min: 360, ideal: 720, max: 1080 },
    height: { min: 360, ideal: 720, max: 1080 },
    deviceId: undefined
  }  
});

// Add stream to videoElement to display a video preview
videoElement.srcObject = cameraStream; 


  


  I then check which mime types are available in the browser and use that info to initialize the MediaRecorder :

  


  const validMimeTypes = [
  "video/webm\;codecs=vp8",
  "video/webm\;codecs=daala",
  "video/webm\;codecs=h264",
  "video/webm",
  "video/mpeg"
];

const getFirstAvailableMimeType = () => {
  for (const mimeType of validMimeTypes) {
    if (MediaRecorder.isTypeSupported(mimeType)) {
      return mimeType;
    }
  }
}

// Initialize Media Recorder
const mediaRecorder = new MediaRecorder(cameraStream, {
  mimeType: getFirstAvailableMimeType(),
});


  


  After I finish recording a video, I upload it to a server and store it on Firebase Storage, so it can be downloaded later.

  


  After downloading a video, I would like to convert it to an MP4 file. I've tried using CloudConvert and HandBrake. Both services have no issues converting videos that were recorded via Chrome on my desktop, but both fail when I try to convert videos recorded via Chrome Mobile on my phone.

  


  When trying to convert the video to MP4 via CloudConvert, the following error is shown :

  


  EBML header parsing failed. /input/import1/69fcceaccc27a0d6eabcb8a65045e87e.webm Invalid data found when processing input


  


  Any ideas how I can resolve this issue ?

  


• audio convert to mp3,pcm and vox using ffmpeg

  8 juillet 2014, par user3789242

  Please can someone help me with the code for ffmpeg.
  I have to use ffmpeg to convert a recorder voice (using HTML5) into mp3,pcm or vox depending on the user’s selection.
  I don’t know how to write the code for ffmpeg if some one can help me with the code or libraries.
  Thank you in advance.

  Here is my code for recording the voice with a visualizer :

  // variables
  
  var leftchannel = [];
  
  var rightchannel = [];
  
  var recorder = null;
  
  var recording = false;
  
  var recordingLength = 0;
  
  var volume = null;
  
  var audioInput = null;
  
  var sampleRate = 44100;
  
  var audioContext = null;
  
  var context = null;
  
  var outputString;
  
  
  
  
  
  
  
  if (!navigator.getUserMedia)
  
     navigator.getUserMedia = navigator.getUserMedia ||
  
                           navigator.webkitGetUserMedia ||
  
                           navigator.mozGetUserMedia || 
  
                           navigator.msGetUserMedia;
  
  
  
   if (navigator.getUserMedia){
  
  navigator.getUserMedia({audio:true}, success, function(e) {
  
  alert('Error capturing audio.');
  
  });
  
  } else alert('getUserMedia not supported in this browser.');
  
  
  
  
  
  
  
  function getVal(value)
  
    {
  
  
  
  // if R is pressed, we start recording
  
  if ( value == "record"){
  
      recording = true;
  
      // reset the buffers for the new recording
  
      leftchannel.length = rightchannel.length = 0;
  
      recordingLength = 0;
  
      document.getElementById('output').innerHTML="Recording now...";
  
  
  
  // if S is pressed, we stop the recording and package the WAV file
  
  } else if ( value == "stop" ){
  
  
  
      // we stop recording
  
      recording = false;
  
      document.getElementById('output').innerHTML="Building wav file...";
  
  
  
      // we flat the left and right channels down
  
      var leftBuffer = mergeBuffers ( leftchannel, recordingLength );
  
      var rightBuffer = mergeBuffers ( rightchannel, recordingLength );
  
      // we interleave both channels together
  
      var interleaved = interleave ( leftBuffer, rightBuffer );
  
  
  
  
  
  
  
      var buffer = new ArrayBuffer(44 + interleaved.length * 2);
  
      var view = new DataView(buffer);
  
  
  
      // RIFF chunk descriptor
  
      writeUTFBytes(view, 0, 'RIFF');
  
      view.setUint32(4, 44 + interleaved.length * 2, true);
  
      writeUTFBytes(view, 8, 'WAVE');
  
      // FMT sub-chunk
  
      writeUTFBytes(view, 12, 'fmt ');
  
      view.setUint32(16, 16, true);
  
      view.setUint16(20, 1, true);
  
      // stereo (2 channels)
  
      view.setUint16(22, 2, true);
  
      view.setUint32(24, sampleRate, true);
  
      view.setUint32(28, sampleRate * 4, true);
  
      view.setUint16(32, 4, true);
  
      view.setUint16(34, 16, true);
  
      // data sub-chunk
  
      writeUTFBytes(view, 36, 'data');
  
      view.setUint32(40, interleaved.length * 2, true);
  
  
  
  
  
      var lng = interleaved.length;
  
      var index = 44;
  
      var volume = 1;
  
      for (var i = 0; i < lng; i++){
  
          view.setInt16(index, interleaved[i] * (0x7FFF * volume), true);
  
          index += 2;
  
      }
  
  
  
      var blob = new Blob ( [ view ], { type : 'audio/wav' } );
  
  
  
      // let's save it locally
  
  
  
      document.getElementById('output').innerHTML='Handing off the file now...';
  
      var url = (window.URL || window.webkitURL).createObjectURL(blob);
  
  
  
      var li = document.createElement('li');
  
      var au = document.createElement('audio');
  
      var hf = document.createElement('a');
  
  
  
      au.controls = true;
  
      au.src = url;
  
      hf.href = url;
  
      hf.download = 'audio_recording_' + new Date().getTime() + '.wav';
  
      hf.innerHTML = hf.download;
  
      li.appendChild(au);
  
      li.appendChild(hf);
  
      recordingList.appendChild(li);
  
  
  
  }
  
  }
  
  
  
  
  
  function success(e){
  
  
  
  audioContext = window.AudioContext || window.webkitAudioContext;
  
  context = new audioContext();
  
  
  
  
  
  volume = context.createGain();
  
  
  
  // creates an audio node from the microphone incoming stream(source)
  
  source = context.createMediaStreamSource(e);
  
  
  
  // connect the stream(source) to the gain node
  
  source.connect(volume);
  
  
  
  var bufferSize = 2048;
  
  
  
  recorder = context.createScriptProcessor(bufferSize, 2, 2);
  
  
  
  //node for the visualizer
  
  analyser = context.createAnalyser();
  
  analyser.smoothingTimeConstant = 0.3;
  
  analyser.fftSize = 512;
  
  
  
  splitter = context.createChannelSplitter();
  
  //when recording happens
  
  recorder.onaudioprocess = function(e){
  
  
  
      if (!recording) return;
  
      var left = e.inputBuffer.getChannelData (0);
  
      var right = e.inputBuffer.getChannelData (1);
  
  
  
      leftchannel.push (new Float32Array (left));
  
      rightchannel.push (new Float32Array (right));
  
      recordingLength += bufferSize;
  
  
  
      // get the average for the first channel
  
      var array =  new Uint8Array(analyser.frequencyBinCount);
  
      analyser.getByteFrequencyData(array);
  
  
  
      var c=document.getElementById("myCanvas");
  
      var ctx = c.getContext("2d");
  
      // clear the current state
  
      ctx.clearRect(0, 0, 1000, 325);
  
      var gradient = ctx.createLinearGradient(0,0,0,300);
  
      gradient.addColorStop(1,'#000000');
  
      gradient.addColorStop(0.75,'#ff0000');
  
      gradient.addColorStop(0.25,'#ffff00');
  
      gradient.addColorStop(0,'#ffffff');
  
      // set the fill style
  
      ctx.fillStyle=gradient;
  
      drawSpectrum(array);
  
      function drawSpectrum(array) {
  
          for ( var i = 0; i < (array.length); i++ ){
  
                  var value = array[i];
  
                  ctx.fillRect(i*5,325-value,3,325);
  
              } 
  
  
  
      }
  
  }
  
  
  
  function getAverageVolume(array) {
  
      var values = 0;
  
      var average;
  
  
  
      var length = array.length;
  
  
  
      // get all the frequency amplitudes
  
      for (var i = 0; i < length; i++) {
  
          values += array[i];
  
      }
  
  
  
      average = values / length;
  
      return average;
  
  }
  
  
  
      // we connect the recorder(node to destination(speakers))
  
      volume.connect(splitter);
  
      splitter.connect(analyser, 0, 0);
  
  
  
      analyser.connect(recorder);
  
      recorder.connect(context.destination);
  
  
  
  }
  
  
  
  
  
  
  
  
  
  function mergeBuffers(channelBuffer, recordingLength){
  
  var result = new Float32Array(recordingLength);
  
  var offset = 0;
  
  var lng = channelBuffer.length;
  
  for (var i = 0; i < lng; i++){
  
  var buffer = channelBuffer[i];
  
  result.set(buffer, offset);
  
  offset += buffer.length;
  
  }
  
      return result;
  
     }
  
  
  
  function interleave(leftChannel, rightChannel){  
  
  var length = leftChannel.length + rightChannel.length;
  
  var result = new Float32Array(length);
  
  
  
  var inputIndex = 0;
  
  
  
  for (var index = 0; index < length; ){
  
  result[index++] = leftChannel[inputIndex];
  
  result[index++] = rightChannel[inputIndex];
  
  inputIndex++;
  
  }
  
  return result;
  
  }
  
  
  
  
  
  function writeUTFBytes(view, offset, string){ 
  
  var lng = string.length;
  
  for (var i = 0; i < lng; i++){
  
  
  
   view.setUint8(offset + i, string.charCodeAt(i));
  
  }
  
  }

• In Flutter, how to get image pixel

  12 janvier 2024, par Pianone

  my code here

  


  var response = await Dio().get(
   url,
   options: Options(responseType: ResponseType.bytes)
);
Uint8List? srcImage = Uint8List.fromList(response.data);
Uint8List? watermark = await captureWaterMark();
Image i = Image.memory(srcImage!);
//how can I get the pixel (Image i) such like 1920*1080 or just width/hight pixel
...tell me how to do...
srcImage = await addWaterMarkByFfmpegCommand(srcImage, watermark);
   final result = await ImageGallerySaver.saveImage(
      srcImage!, name: name,
   );


  


  i need get the pic pixel so that i can use it in ffmpeg command, it a func that add a watermark into srcImage, but cause their pixel ratio too diff to adapted watermark

  


  i try to get pixel from ffmpeg... but i failed

  


  /// addWaterMark by using ffmpeg Command
Future addWaterMarkByFfmpegCommand(Uint8List srcImg, Uint8List watermark) async {
  try {
    final Directory tempDir = await Directory.systemTemp.createTemp();
    final File image1File = File('${tempDir.path}/srcImg.jpg');
    await image1File.writeAsBytes(srcImg);
    final File image2File = File('${tempDir.path}/watermark.png');
    await image2File.writeAsBytes(watermark);

    final String outputFilePath = '${tempDir.path}/output.jpg';
    //when i get srcImage pixel, the positions in bold(iw*1) in the following commands will be replaced to make watermark adapted
    final String command =
        '-i ${image1File.path} -i ${image2File.path} -filter_complex "[1:v]scale=**iw*1**:-1[v1];[0:v][v1]overlay=10:10" -frames:v 1 $outputFilePath';
    await FFmpegKit.execute(command);

    final File outputFile = File(outputFilePath);
    final Uint8List outputBytes = await outputFile.readAsBytes();
    return outputBytes;
  } catch (e) {
    print('Error executing ffmpeg command: $e');
  }
  return null;
}


  


  ps : i am new to flutter and ffmpeg, plz help me, I'd appreciate, thanks alot