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• Delay issue in Audio/Video Merging through Python

  2 février 2015, par Fahadkalis

  I am writing a program in python on RaspberryPi, to record video on a Picam and capture audio through a Microphone attached with USB AUDIO DEVICE.

  On combining both files through ffmpeg, till 30sec both Audio/video synchronize well but after 30sec, I start to experiance a delay problem.

  Can you please guide me in resolving this issue ?

  import picamera, subprocess, os
  
  import pyaudio,wave,sys
  
  
  
  CHUNK = 8192
  
  FORMAT = pyaudio.paInt16
  
  CHANNELS = 1
  
  RATE = 44100
  
  RECORD_SECONDS = 60                                                 #"Recording Duration"
  
  WAVE_OUTPUT_FILENAME = 'Audio.wav'
  
  H264_OUTPUT_FILENAME = 'Video.h264'
  
  frames = []
  
  with picamera.PiCamera() as camera:
  
      camera.resolution= (640,480)
  
      p = pyaudio.PyAudio()
  
      stream = p.open(format=FORMAT,
  
                      channels = CHANNELS,
  
                      rate = RATE,
  
                      input = True,
  
                      input_device_index = 0,
  
                      frames_per_buffer = CHUNK)
  
      camera.start_preview(fullscreen=False, window=(930, 0, 425, 295))# "Start Video Preview"
  
      camera.start_recording(H264_OUTPUT_FILENAME, quality = 30)                     # "Start Video Recording"
  
      # "Start Audio Dubbing"        
  
      for i in range(0, int(RATE / CHUNK * RECORD_SECONDS)):
  
          data = stream.read(CHUNK)
  
          frames.append(data)
  
      stream.stop_stream()                                             # "Pause the Stream"
  
      stream.close()                                                   # "Stream Stop"
  
      p.terminate()                                                    # "Stream Cloase"
  
      camera.stop_recording()                                          # "Pause" the recording
  
      camera.stop_preview()                                            # "Stop Preview"
  
      camera.close()                                                   # "Camera Close"
  
  # Creation of MIC WAVE FILE
  
  wf = wave.open(WAVE_OUTPUT_FILENAME, 'wb')                              
  
  wf.setnchannels(CHANNELS)
  
  wf.setsampwidth(p.get_sample_size(FORMAT))
  
  wf.setframerate(RATE)
  
  wf.writeframes(b''.join(frames))
  
  wf.close()
  
  # Combining/Merging of Audio/Video File into mkv
  
  cmd = 'ffmpeg -y -i Audio.wav  -r 30 -i Video.h264  -filter:a aresample=async=1 -c:a flac -c:v copy av.mkv'
  
  subprocess.call(cmd, shell=True)                                     # "Muxing Done
  
  print('Muxing Done')

• FFMPEG keep an original canva size with a background image

  26 novembre 2019, par romain1304

  Im trying to generate a wave with ffmpeg and audio input.
  Now i generate a wave, then my background image fit the canva and the canva becomes the size of the background image.
  I would like to keep the original size of the canva 1280x720.
  And i would like the background image to have the size i would put on input.

  So basically i would like one canva with a size of 1280x720 , one image with certain coordinate and a certain size and one waveforme.

  This is my result :
  

  This is the result i would like to obtain :

  

  If anyone can help !
  Thanks,

• How to save/encode recorded raw PCM Data as AAC/MP4 format file in Android

  28 janvier 2015, par INVISIBLE

  i want to save recorder pcm data as aac/mp4 format file.
  i am using AudioRecord class for recording audio in android. i have success fully saved it as wave file by adding a wave header to raw data. but dont know how to save it as aac/mp4 file, because aac/mp4 format is compressed then wave.
  the methods i am using for saving pcm data as wave is pasted below.

  recorder = new AudioRecord(MediaRecorder.AudioSource.MIC,
  
              SavedSampleRate, RECORDER_CHANNELS, RECORDER_AUDIO_ENCODING,
  
              bufferSize);
  
  recorder.startRecording();
  
  isRecording = true;
  
  
  
  isRecording = true;
  
  
  
  recordingThread = new Thread(new Runnable() {
  
      @Override
  
      public void run() {
  
          writeAudioDataToFile();
  
      }
  
  }, "AudioRecorder Thread");
  
  
  
  recordingThread.start();

  second

  private void writeAudioDataToFile() {
  
  
  
      byte data[] = new byte[bufferSize];
  
      // short sData[] = new short[bufferSize];
  
      String filename = getTempFilename();
  
      FileOutputStream os = null;
  
  
  
      try {
  
          os = new FileOutputStream(filename);
  
      } catch (Exception e) {
  
          e.printStackTrace();
  
      }
  
  
  
      int read = 0;
  
  
  
      if (null != os) {
  
          while (isRecording) {
  
              double sum = 0;
  
              read = recorder.read(data, 0, bufferSize);
  
  
  
              if (AudioRecord.ERROR_INVALID_OPERATION != read) {
  
                  try {
  
  
  
                      synchronized (this) {
  
  
  
  
  
                          // Necessary in order to convert negative shorts!
  
                          final int USHORT_MASK = (1 << 16) - 1;
  
  
  
                          final ByteBuffer buf = ByteBuffer.wrap(data).order(
  
                                  ByteOrder.LITTLE_ENDIAN);
  
  
  
                          final ByteBuffer newBuf = ByteBuffer.allocate(
  
                                  data.length).order(ByteOrder.LITTLE_ENDIAN);
  
  
  
                          int sample;
  
  
  
                          while (buf.hasRemaining()) {
  
  
  
  
  
  
  
                              short shortSample = buf.getShort();
  
                              sample = (int) shortSample & USHORT_MASK;
  
  
  
  
  
  
  
                              sample = sample * db_value_global;
  
                              sample = mRmsFilterSetting.filter
  
                                      .apply((((int) 0) | shortSample)
  
                                              * db_value_global);
  
  
  
  
  
  
  
                              newBuf.putShort((short) sample);
  
                          }
  
  
  
                          data = newBuf.array();
  
  
  
                          os.write(data);
  
  
  
  
  
  
  
  
  
  
  
                      }
  
  
  
                  } catch (Exception e) {
  
                      e.printStackTrace();
  
                  }
  
              }
  
          }
  
  
  
          try {
  
              os.close();
  
          } catch (Exception e) {
  
              e.printStackTrace();
  
          }
  
      }
  
  }

  and finally saving it as

  private void copyWaveFile(ArrayList<string> inFilename, String outFilename) {
  
      FileInputStream[] in = null;
  
      FileOutputStream out = null;
  
      long totalAudioLen = 0;
  
      long totalDataLen = totalAudioLen + 36;
  
      long longSampleRate = SavedSampleRate;
  
      int channels = 2;
  
      long byteRate = RECORDER_BPP * SavedSampleRate * channels / 8;
  
  
  
      byte[] data = new byte[bufferSize];
  
  
  
      try {
  
          out = new FileOutputStream(outFilename);
  
  
  
          in = new FileInputStream[inFilename.size()];
  
  
  
          for (int i = 0; i &lt; in.length; i++) {
  
              in[i] = new FileInputStream(inFilename.get(i));
  
              totalAudioLen += in[i].getChannel().size();
  
          }
  
  
  
          totalDataLen = totalAudioLen + 36;
  
  
  
          WriteWaveFileHeader(out, totalAudioLen, totalDataLen,
  
                  longSampleRate, channels, byteRate);
  
  
  
          for (int i = 0; i &lt; in.length; i++) {
  
              while (in[i].read(data) != -1) {
  
                  out.write(data);
  
              }
  
  
  
              in[i].close();
  
          }
  
  
  
          out.close();
  
      } catch (Exception e) {
  
          e.printStackTrace();
  
      } 
  
  }
  
  
  
  
  
  
  
  private void WriteWaveFileHeader(FileOutputStream out, long totalAudioLen,
  
          long totalDataLen, long longSampleRate, int channels, long byteRate)
  
          throws IOException {
  
  
  
      byte[] header = new byte[44];
  
  
  
      header[0] = 'R'; // RIFF/WAVE header
  
      header[1] = 'I';
  
      header[2] = 'F';
  
      header[3] = 'F';
  
      header[4] = (byte) (totalDataLen &amp; 0xff);
  
      header[5] = (byte) ((totalDataLen >> 8) &amp; 0xff);
  
      header[6] = (byte) ((totalDataLen >> 16) &amp; 0xff);
  
      header[7] = (byte) ((totalDataLen >> 24) &amp; 0xff);
  
      header[8] = 'W';
  
      header[9] = 'A';
  
      header[10] = 'V';
  
      header[11] = 'E';
  
      header[12] = 'f'; // 'fmt ' chunk
  
      header[13] = 'm';
  
      header[14] = 't';
  
      header[15] = ' ';
  
      header[16] = 16; // 4 bytes: size of 'fmt ' chunk
  
      header[17] = 0;
  
      header[18] = 0;
  
      header[19] = 0;
  
      header[20] = 1; // format = 1
  
      header[21] = 0;
  
      header[22] = (byte) channels;
  
      header[23] = 0;
  
      header[24] = (byte) (longSampleRate &amp; 0xff);
  
      header[25] = (byte) ((longSampleRate >> 8) &amp; 0xff);
  
      header[26] = (byte) ((longSampleRate >> 16) &amp; 0xff);
  
      header[27] = (byte) ((longSampleRate >> 24) &amp; 0xff);
  
      header[28] = (byte) (byteRate &amp; 0xff);
  
      header[29] = (byte) ((byteRate >> 8) &amp; 0xff);
  
      header[30] = (byte) ((byteRate >> 16) &amp; 0xff);
  
      header[31] = (byte) ((byteRate >> 24) &amp; 0xff);
  
      header[32] = (byte) (2 * 16 / 8); // block align
  
      header[33] = 0;
  
      header[34] = RECORDER_BPP; // bits per sample
  
      header[35] = 0;
  
      header[36] = 'd';
  
      header[37] = 'a';
  
      header[38] = 't';
  
      header[39] = 'a';
  
      header[40] = (byte) (totalAudioLen &amp; 0xff);
  
      header[41] = (byte) ((totalAudioLen >> 8) &amp; 0xff);
  
      header[42] = (byte) ((totalAudioLen >> 16) &amp; 0xff);
  
      header[43] = (byte) ((totalAudioLen >> 24) &amp; 0xff);
  
  
  
      out.write(header, 0, 44);
  
  }
  
  </string>

  in this piece of code i am recording small PCM files with AudioRecord and saving them as wave file by adding wave header.

  is there any step by step tutorial for how to save pcm data as mp4/aac file.

  thanks in advance.