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• Using ffmpeg, extract audio streams from video file and output to single stereo wav file

  8 décembre 2016, par Quantum_Kernel

  I’ve been trying for a few hours to get the right arguments to do the below operation with ffmpeg, but i’m a bit out of my depth. If anyone can give me some guidance, that would be very helpful.

  Input file is MXF with one video track and two separate 48k 24b PCM audio tracks.
  I want to extract just the audio, map first track to left, second track to right and output as a stereo wave file.

  I am trying variations on the below command, but it seems to be unhappy about the video stream, giving the error

  "mapchan : stream #0.0 is not an audio stream."

  ffmpeg -i test2.mxf -vn -map_channel 0.0.1 output.wav_CH0 -map_channel 0.0.2 output.wav_CH1

  Here is ffmpeg’s analysis of the streams in case it is helpful :

      Stream #1:0: Video: mpeg2video (4:2:2), yuv422p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], max. 50000 kb/s, 25 fps, 25 tbr, 25 tbn, 50 tbc
  
  Stream #1:1: Audio: pcm_s24le, 48000 Hz, mono, s32, 1152 kb/s
  
  Stream #1:2: Audio: pcm_s24le, 48000 Hz, mono, s32, 1152 kb/s
  
  Stream #1:3: Audio: pcm_s24le, 48000 Hz, mono, s32, 1152 kb/s
  
  Stream #1:4: Audio: pcm_s24le, 48000 Hz, mono, s32, 1152 kb/s
  
  Stream #1:5: Audio: pcm_s24le, 48000 Hz, mono, s32, 1152 kb/s
  
  Stream #1:6: Audio: pcm_s24le, 48000 Hz, mono, s32, 1152 kb/s
  
  Stream #1:7: Audio: pcm_s24le, 48000 Hz, mono, s32, 1152 kb/s
  
  Stream #1:8: Audio: pcm_s24le, 48000 Hz, mono, s32, 1152 kb/s

• Can not find file with ffmpeg

  3 août 2018, par P.Ung

  I am programming a server in node.js to process a audio file.
  I save the file with this code :

  app.use(upload());
  
  app.get("/", function (req, res) {
  
  res.sendFile("index.html")
  
  });
  
  //Uploaded files will be saved
  
  app.post("/", function (req, res) {
  
  if (req.files) {
  
      var file = req.files.filename,
  
          filename = file.name;
  
      file.mv("./upload/" + filename, function (err) {
  
          if (err) {
  
              console.log("err");
  
          }
  
          else {
  
              res.send("Done");
  
              console.log(filename);
  
              convert(filename);
  
  
  
          }
  
      })
  
  }
  
  })

  I save the file in my upload directory. There everthing works great but now comes the problem.
  I convert the file with ffmpeg

  function convert(filename) {    
  
  var realName = "./upload/" + filename;
  
  var newName = "./output/" + filename.substr(0, filename.length - 4) + ".flac";
  
  ffmpegN = ffmpeg(realName);
  
  ffmpegN.audioBitrate(16).audioFrequency(16000).withAudioCodec('flac').format("flac").save(outputFile);
  
  
  
  ffmpeg(realName)
  
      .toFormat('flac')
  
      .on('error', (err) => {
  
          console.log('An error occurred: ' + err.message);
  
      })
  
      .on('progress', (progress) => {
  
          // console.log(JSON.stringify(progress));
  
          console.log('Processing: ' + progress.targetSize + ' KB converted');
  
      })
  
      .on('end', () => {
  
          console.log('Processing finished !');
  
      })
  
      .save(newName);//path where you want to save your file    
  
  SpeechToText(newName);
  
  }

  Then I want to pass this file to the google speech api. But then I get the error that the file is not found
  Here is the code for the Speech Api :

  function SpeechToText(path) {
  
  // The name of the audio file to transcribe
  
  const fileName = path;
  
  
  
  // Reads a local audio file and converts it to base64
  
  const file = fs.readFileSync(fileName);
  
  const audioBytes = file.toString('base64');
  
  
  
  // The audio file's encoding, sample rate in hertz, and BCP-47 language code
  
  const audio = {
  
      content: audioBytes,
  
  };
  
  const config = {
  
      encoding: 'FLAC',        
  
      languageCode: 'de-DE',
  
  };
  
  const request = {
  
      audio: audio,
  
      config: config,
  
  };
  
  
  
  // Detects speech in the audio file
  
  client
  
      .recognize(request)
  
      .then(data => {
  
          const response = data[0];
  
          const transcription = response.results
  
              .map(result => result.alternatives[0].transcript)
  
              .join('\n');
  
          console.log(`Transcription: ${transcription}`);
  
      })
  
      .catch(err => {
  
          console.error('ERROR:', err);
  
      });
  
  }

  The thing is that if I upload a file everything works. But if I try it for a second time the error occurs :

  fs.js:646
  
  return binding.open(pathModule._makeLong(path), stringToFlags(flags), mode);
  
               ^
  
  
  
  Error: ENOENT: no such file or directory, open                 
  
  'C:\Users\paulu\desktop\API\output\sample.flac'
  
  at Object.fs.openSync (fs.js:646:18)
  
  at Object.fs.readFileSync (fs.js:551:33)
  
  at SpeechToText (C:\Users\paulu\desktop\API\server.js:68:21)
  
  at convert (C:\Users\paulu\desktop\API\server.js:121:5)
  
  at C:\Users\paulu\desktop\API\server.js:50:17
  
  at doMove (C:\Users\paulu\desktop\API\node_modules\express- 
  
  fileupload\lib\index.js:152:17)
  
  at WriteStream.<anonymous> (C:\Users\paulu\desktop\API\node_modules\express- 
  
  fileupload\lib\in                             dex.js:182:15)
  
  at emitNone (events.js:106:13)
  
  at WriteStream.emit (events.js:208:7)
  
  at fs.close (fs.js:2094:12)
  
  </anonymous>

  Thank you for all answers !

• How to concat the mp3 file and webm file into a new webm file ?

  12 août 2015, par it_is_a_literature

  There is a webm file that contains no audio. I want to merge an audio file with this video. I’ve tried the following command :

  ffmpeg -i /home/test.mp3  -i /home/output.webm -vcodec copy -acodec copy /home/newtest.webm

  And received the error :

  Could not write header for output file #0 (incorrect codec parameters ?):         Invalid argument.