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• Transcoding audio using xuggler

  15 novembre 2017, par amd

  I am trying to convert an audio file with the header

  Opening audio decoder: [pcm] Uncompressed PCM audio decoder
  
  AUDIO: 44100 Hz, 2 ch, s16le, 1411.2 kbit/100.00% (ratio: 176400->176400)
  
  Selected audio codec: [pcm] afm: pcm (Uncompressed PCM)

  I want to transcode this file to mp3 format. I have following code snippet but its not working well. I have written it using XUGGLER code snippet for transcoding audio and video.

  Audio decoder is

      audioDecoder = IStreamCoder.make(IStreamCoder.Direction.DECODING, ICodec.findDecodingCodec(ICodec.ID.CODEC_ID_PCM_S16LE));
  
      audioDecoder.setSampleRate(44100);
  
      audioDecoder.setBitRate(176400);
  
      audioDecoder.setChannels(2);
  
      audioDecoder.setTimeBase(IRational.make(1,1000));
  
      if (audioDecoder.open(IMetaData.make(), IMetaData.make()) < 0)
  
          return false;
  
      return true; 

  Audio encoder is

      outContainer = IContainer.make();
  
      outContainerFormat = IContainerFormat.make();
  
      outContainerFormat.setOutputFormat("mp3", urlOut, null);
  
      int retVal = outContainer.open(urlOut, IContainer.Type.WRITE, outContainerFormat);
  
      if (retVal < 0) {
  
          System.out.println("Could not open output container");
  
          return false;
  
      }
  
      outAudioCoder = IStreamCoder.make(IStreamCoder.Direction.ENCODING, ICodec.findEncodingCodec(ICodec.ID.CODEC_ID_MP3));
  
      outAudioStream = outContainer.addNewStream(outAudioCoder);
  
      outAudioCoder.setSampleRate(new Integer(44100));
  
      outAudioCoder.setChannels(2);
  
      retVal = outAudioCoder.open(IMetaData.make(), IMetaData.make());
  
      if (retVal < 0) {
  
          System.out.println("Could not open audio coder");
  
          return false;
  
      }
  
      retVal = outContainer.writeHeader();
  
      if (retVal < 0) {
  
          System.out.println("Could not write output FLV header: ");
  
          return false;
  
      }
  
      return true;

  And here is encode method where i send packets of 32 byte to transcode

  public void encode(byte[] audioFrame){
  
      //duration of 1 video frame
  
      long lastVideoPts = 0;
  
  
  
      IPacket packet_out = IPacket.make();
  
      int lastPos = 0;
  
      int lastPos_out = 0;
  
  
  
      IAudioSamples audioSamples = IAudioSamples.make(48000, audioDecoder.getChannels());
  
      IAudioSamples audioSamples_resampled = IAudioSamples.make(48000, audioDecoder.getChannels());
  
  
  
      //we always have 32 bytes/sample
  
      int pos = 0;
  
      int audioFrameLength = audioFrame.length;
  
      int audioFrameCnt = 1;
  
      iBuffer = IBuffer.make(null, audioFrame, 0, audioFrameLength);
  
      IPacket packet = IPacket.make(iBuffer);
  
      //packet.setKeyPacket(true);
  
      packet.setTimeBase(IRational.make(1,1000));
  
      packet.setDuration(20);
  
      packet.setDts(audioFrameCnt*20);
  
      packet.setPts(audioFrameCnt*20);
  
      packet.setStreamIndex(1);
  
      packet.setPosition(lastPos);
  
      lastPos+=audioFrameLength;
  
      int pksz = packet.getSize();
  
      packet.setComplete(true, pksz);
  
      /*
  
      * A packet can actually contain multiple samples
  
      */
  
      int offset = 0;
  
      int retVal;
  
      while(offset < packet.getSize())
  
      {
  
          int bytesDecoded = audioDecoder.decodeAudio(audioSamples, packet, offset);
  
          if (bytesDecoded < 0)
  
              throw new RuntimeException("got error decoding audio ");
  
          offset += bytesDecoded;
  
          if (audioSamples.isComplete())
  
          {
  
              int samplesConsumed = 0;
  
              while (samplesConsumed < audioSamples.getNumSamples()) {
  
                  retVal = outAudioCoder.encodeAudio(packet_out, audioSamples, samplesConsumed);
  
                  if (retVal <= 0)
  
                      throw new RuntimeException("Could not encode audio");
  
                  samplesConsumed += retVal;
  
                  if (packet_out.isComplete()) {
  
                      packet_out.setPosition(lastPos_out);
  
                      packet_out.setStreamIndex(1);
  
                      lastPos_out+=packet_out.getSize();
  
                      retVal = outContainer.writePacket(packet_out);
  
                      if(retVal < 0){
  
                          throw new RuntimeException("Could not write data packet");
  
                      }
  
                  }
  
              }
  
          }
  
  
  
      }
  
  
  
  }

  I get an output file but it doesnt get played. I have very little experience of audio encoding and sampling. Thanks in advance.

• converting mp4 file to zero KB .png file : FFmpeg

  6 novembre 2017, par muskan

  Used below command for converting 2,981kb of file1.mp4 to file1.png :

  "ffmpeg.exe -i file1.mp4 -ss 00:00:10.00 -s "315"x"210"-f image2 -vframes 1 file1.png"

  using following code to execute the command :

  public int ProcessRun(string filename, string arguments, int waitTimeSeconds)
  
  {
  
      if (!System.IO.File.Exists(filename))
  
      {
  
          var Message = $"Converter file not found.";
  
          DialogResult result = DisplayError(Message);
  
      }
  
      int returnVal = 0;
  
      try
  
      {
  
          using (Process process = new Process())
  
          {
  
              process.StartInfo.FileName = filename;
  
              process.StartInfo.Arguments = arguments;
  
              process.StartInfo.UseShellExecute = false;
  
              process.StartInfo.RedirectStandardOutput = true;
  
              process.StartInfo.RedirectStandardError = true;
  
  
  
              StringBuilder output = new StringBuilder();
  
              StringBuilder error = new StringBuilder();
  
  
  
              using (AutoResetEvent outputWaitHandle = new AutoResetEvent(false))
  
              using (AutoResetEvent errorWaitHandle = new AutoResetEvent(false))
  
              {
  
                  process.OutputDataReceived += (sender, e) =>
  
                  {
  
                      if (e.Data == null)
  
                      {
  
                          outputWaitHandle.Set();
  
                      }
  
                      else
  
                      {
  
                          output.AppendLine(e.Data);
  
                      }
  
                  };
  
                  process.ErrorDataReceived += (sender, e) =>
  
                  {
  
                      if (e.Data == null)
  
                      {
  
                          errorWaitHandle.Set();
  
                      }
  
                      else
  
                      {
  
                          error.AppendLine(e.Data);
  
                      }
  
                  };
  
  
  
                  process.Start();
  
  
  
                  process.BeginOutputReadLine();
  
                  process.BeginErrorReadLine();
  
  
  
                  if (process.WaitForExit((int)TimeSpan.FromSeconds(waitTimeSeconds).TotalMilliseconds) &&
  
                       outputWaitHandle.WaitOne((int)TimeSpan.FromSeconds(waitTimeSeconds).TotalMilliseconds) &&
  
                       errorWaitHandle.WaitOne((int)TimeSpan.FromSeconds(waitTimeSeconds).TotalMilliseconds))
  
                  {
  
                     returnVal = process.ExitCode;
  
                  }
  
                  returnVal = process.ExitCode;
  
              }
  
          }
  
      }
  
      catch (Exception ex)
  
      {
  
          throw ex;
  
      }
  
      finally { }
  
      return returnVal;
  
  }

  where filename is filepath of my "ffmpeg.exe"
  arguments is "-i file1.mp4 -ss 00:00:10.00 -s "315"x"210"-f image2 -vframes 1 file1.png"
  waittimeseconds 60000

  But this always return me the file1.png of size 0kb.
  Getting following errorlog :

  ffmpeg version N-66289-gb76d613 Copyright (c) 2000-2014 the FFmpeg developers
  built on Sep 15 2014 22:02:10 with gcc 4.8.3 (GCC)
  configuration : —enable-gpl —enable-version3 —disable-w32threads —enable-avisynth —enable-bzlib —enable-fontconfig —enable-frei0r —enable-gnutls —enable-iconv —enable-libass —enable-libbluray —enable-libbs2b —enable-libcaca —enable-libfreetype —enable-libgme —enable-libgsm —enable-libilbc —enable-libmodplug —enable-libmp3lame —enable-libopencore-amrnb —enable-libopencore-amrwb —enable-libopenjpeg —enable-libopus —enable-librtmp —enable-libschroedinger —enable-libsoxr —enable-libspeex —enable-libtheora —enable-libtwolame —enable-libvidstab —enable-libvo-aacenc —enable-libvo-amrwbenc —enable-libvorbis —enable-libvpx —enable-libwavpack —enable-libwebp —enable-libx264 —enable-libx265 —enable-libxavs —enable-libxvid —enable-decklink —enable-zlib
  libavutil 54. 7.100 / 54. 7.100
  libavcodec 56. 1.100 / 56. 1.100
  libavformat 56. 4.101 / 56. 4.101
  libavdevice 56. 0.100 / 56. 0.100
  libavfilter 5. 1.100 / 5. 1.100
  libswscale 3. 0.100 / 3. 0.100
  libswresample 1. 1.100 / 1. 1.100
  libpostproc 53. 0.100 / 53. 0.100
  file1.mp4 : Permission denied

  How can I fix it ?

• Save a partial video file locally using NodeJS

  25 octobre 2017, par Sami

  I have a serverless web application that is deployed on AWS and I have to take a screenshot from an uploaded video to S3. I am using ffmpeg to extract the screenshot but the only drawback is that I have to download the video file first in order to let ffmpeg work with it.
  Knowing the fact I am using AWS Lambda and I don’t have limits for video length users might upload large files which makes AWS Lambda to hit the storage limit.
  To overcome this I thought of downloading a small chunk of the video and use it with ffmpeg to extract the thumbnail so using the S3.getOjbect method with range params I was able to download a chunk of the file but ffmpeg couldn’t understand it.
  Here is my code :

  s3.getObject({
  
    Bucket: bucketName,
  
    Key: key,
  
    Range: 'bytes=0-1048576'
  
  }, (err, data) => {
  
    fs.writeFile(fileName, data.Body, error => {
  
      if (error)
  
        console.log(error)
  
      else
  
        console.log('File saved');
  
    })
  
  })

  And the code to extract the thumbnail :

  const ffmpeg = require('fluent-ffmpeg');
  
  new ffmpeg(fileName).screenshots({
  
    timestamps: [0],
  
    filename: 'thumb.png',
  
    folder: '.'
  
  })

  And I am getting this error from ffmpeg

  Error: ffmpeg exited with code 1: ./test.mp4: Invalid data found when processing input

  I know there is a problem in saving the file like this but I couldn’t find any solution that solves my problem. If anybody has one that would be much appreciated.

  UPDATE :
  It turns out that ffmpeg does this for me, I just gave it the url and it downloaded what it needs to render the screenshot without the need to download the file locally and the code looks like this :

  const ffmpeg = require('fluent-ffmpeg');
  
  new ffmpeg(url).screenshots({
  
    timestamps: [0],
  
    filename: 'thumb.png',
  
    folder: '.'
  
  })