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• m4a/mp3 files to wav for Bing Speech API

  17 décembre 2018, par Waqas

  Bing Speech API only accepts wav files so I have been trying to convert m4a (Skype) and mp3 (Facebook) audio files I am getting in my chatbot to wav format. I am using fluent-ffmpeg in node.js.

  For now, I am downloading the audio file, converting it to wav and returning the piped output for use ahead.

  if (attachment.contentType === 'audio/x-m4a') {
  
    request.get(attachment.contentUrl).pipe(fs.createWriteStream('file.m4a'));
  
    var command = ffmpeg('file.m4a')
  
          .toFormat('wav')
  
          .on('error', function (err) {
  
              console.log('An error occurred: ' + err.message);
  
          })
  
          .on('progress', function (progress) {
  
              // console.log(JSON.stringify(progress));
  
              console.log('Processing: ' + progress.targetSize + ' KB converted');
  
          })
  
          .on('end', function () {
  
              console.log('Processing finished !');
  
          });
  
  
  
    return command.pipe();
  
  }

  Right now, the conversion works when I send the m4a file through the botframework-emulator on my pc. But when I specify my pc as the endpoint (through ngrok) and try to send the m4a file from the chat test at the bot framework developer end, ffmpeg returns an error :

  An error occurred: ffmpeg exited with code 1: file.m4a: Invalid data found when processing input

  But when I play the downloaded m4a file, it plays alright.

  The content URL is https in the second case if that matters.

  Kindly help me with two things :

  1. Downloading, Converting and Returning without storing anything on my end
  2. Downloading/Accessing m4a/mp3 files properly

  I am new to streams, pipes and ffmpeg and all the above code is after googling.

• Video codec not supported error when adding audio to mp4

  18 février 2019, par WPMed

  I work on an application which you can use to make still photos move. It’s basically a png sequence to mp4 converter.
  Recently we introduced a feature where users can add sound effects to the video.
  Since we released this feature, some users experience problems with the exported video. When they save the file and try to play it, they get a "Video codec not supported" error message. All they get is a black screen, and the audio playing in the background. I use FFmpeg to add audio (in mp3 format) to the mp4 video.
  Here’s an example video, which plays fine on my Mac and on my Samsung Galaxy S6 and S8, but buggy on Samsung SM-A310F (Android 7.0). This is how it looks like on the device.
  I tried to re-encode this video with all the FFmpeg commands I could find, but none of them seemed to work. Can someone spot something that’s not compatible with Android by analyzing the video I linked ?

• The duration of movie file recorded by AVAssetWriter is not correct

  1er mars 2016, par ideawu

  I am recording video files with AVAssetWriter combining with AVCaptureVideoDataOutputSampleBufferDelegate. So I can take control over every frame the camara gives in the method :

  - (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection{
  
      double time = CMTimeGetSeconds(CMSampleBufferGetPresentationTimeStamp(sampleBuffer));
  
      NSLog(@"%f", time);
  
      [_videoInput appendSampleBuffer:sampleBuffer];
  
  }

  So I am so sure how many samples have been written to AVAssetWriter via AVAssetWriterInput, and I know exactly the start time and end time of the samples being written. The duration is calculated by end_time - start_time. Say the duration calculated in the video capture programm is 0.5 second.

  I get the .mov/.mp4 file on disk, inspected with ffmpeg -i, it shows a very different duration.

  ffmpeg -i m003.mp4 2>&1 | grep Dura
  
    Duration: 00:00:01.37, start: 0.836667, bitrate: 95 kb/s

  The movie file show a duration of 1.37 seconds, which it’s quite different with the EXACT duration 0.5.

  Does any one knows the reason ?