/**
     * Reads media data from this <tt>PullBufferStream</tt> into a specific <tt>Buffer</tt> with
     * blocking.
     *
     * @param buffer the <tt>Buffer</tt> in which media data is to be read from this
     *     <tt>PullBufferStream</tt>
     * @throws IOException if anything goes wrong while reading media data from this
     *     <tt>PullBufferStream</tt> into the specified <tt>buffer</tt>
     * @see javax.media.protocol.PullBufferStream#read(javax.media.Buffer)
     */
    public void read(Buffer buffer) throws IOException {
      if (setThreadPriority) {
        setThreadPriority = false;
        setThreadPriority();
      }

      Object data = buffer.getData();
      int length = this.length;

      if (data instanceof byte[]) {
        if (((byte[]) data).length < length) data = null;
      } else data = null;
      if (data == null) {
        data = new byte[length];
        buffer.setData(data);
      }

      int toRead = length;
      byte[] bytes = (byte[]) data;
      int offset = 0;

      buffer.setLength(0);
      while (toRead > 0) {
        int read;

        synchronized (this) {
          if (audioRecord.getRecordingState() == AudioRecord.RECORDSTATE_RECORDING)
            read = audioRecord.read(bytes, offset, toRead);
          else break;
        }

        if (read < 0) {
          throw new IOException(
              AudioRecord.class.getName() + "#read(byte[], int, int) returned " + read);
        } else {
          buffer.setLength(buffer.getLength() + read);
          offset += read;
          toRead -= read;
        }
      }
      buffer.setOffset(0);

      // Apply software gain.
      if (gainControl != null) {
        BasicVolumeControl.applyGain(gainControl, bytes, buffer.getOffset(), buffer.getLength());
      }
    }
    /** Closes the connection to the media source of the associated <tt>DataSource</tt>. */
    public synchronized void disconnect() {
      if (audioRecord != null) {
        audioRecord.release();
        audioRecord = null;

        setThreadPriority = true;
      }
    }
    /**
     * Stops the transfer of media data from this <tt>AbstractBufferStream</tt>.
     *
     * @throws IOException if anything goes wrong while stopping the transfer of media data from
     *     this <tt>AbstractBufferStream</tt>
     * @see AbstractBufferStream#stop()
     */
    @Override
    public void stop() throws IOException {
      synchronized (this) {
        if (audioRecord != null) {
          audioRecord.stop();
          setThreadPriority = true;
        }
      }

      super.stop();
    }
    /** Configures echo cancellation and noise suppression effects. */
    @TargetApi(Build.VERSION_CODES.JELLY_BEAN)
    private void configureEffects() {
      if (!AndroidUtils.hasAPI(16)) return;

      AudioSystem audioSystem =
          AudioSystem.getAudioSystem(AudioSystem.LOCATOR_PROTOCOL_AUDIORECORD);

      // Creates echo canceler if available
      if (AcousticEchoCanceler.isAvailable()) {
        AcousticEchoCanceler echoCanceller =
            AcousticEchoCanceler.create(audioRecord.getAudioSessionId());
        if (echoCanceller != null) {
          echoCanceller.setEnableStatusListener(this);
          echoCanceller.setEnabled(audioSystem.isEchoCancel());
          logger.info("Echo cancellation: " + echoCanceller.getEnabled());
        }
      }

      // Automatic gain control
      if (AutomaticGainControl.isAvailable()) {
        AutomaticGainControl agc = AutomaticGainControl.create(audioRecord.getAudioSessionId());
        if (agc != null) {
          agc.setEnableStatusListener(this);
          agc.setEnabled(audioSystem.isAutomaticGainControl());
          logger.info("Auto gain control: " + agc.getEnabled());
        }
      }

      // Creates noise suppressor if available
      if (NoiseSuppressor.isAvailable()) {
        NoiseSuppressor noiseSuppressor = NoiseSuppressor.create(audioRecord.getAudioSessionId());
        if (noiseSuppressor != null) {
          noiseSuppressor.setEnableStatusListener(this);
          noiseSuppressor.setEnabled(audioSystem.isDenoise());
          logger.info("Noise suppressor: " + noiseSuppressor.getEnabled());
        }
      }
    }
    /**
     * Starts the transfer of media data from this <tt>AbstractBufferStream</tt>.
     *
     * @throws IOException if anything goes wrong while starting the transfer of media data from
     *     this <tt>AbstractBufferStream</tt>
     * @see AbstractBufferStream#start()
     */
    @Override
    public void start() throws IOException {
      /*
       * Connect upon start because the connect has been delayed to allow
       * this AudioRecordStream to respect requests to set its format.
       */
      synchronized (this) {
        if (audioRecord == null) connect();
      }

      super.start();

      synchronized (this) {
        if (audioRecord != null) {
          setThreadPriority = true;
          audioRecord.startRecording();
        }
      }
    }
    /**
     * Opens a connection to the media source of the associated <tt>DataSource</tt>.
     *
     * @throws IOException if anything goes wrong while opening a connection to the media source of
     *     the associated <tt>DataSource</tt>
     */
    public synchronized void connect() throws IOException {
      javax.media.format.AudioFormat af = (javax.media.format.AudioFormat) getFormat();
      int channels = af.getChannels();
      int channelConfig;

      switch (channels) {
        case Format.NOT_SPECIFIED:
        case 1:
          channelConfig = AudioFormat.CHANNEL_IN_MONO;
          break;
        case 2:
          channelConfig = AudioFormat.CHANNEL_IN_STEREO;
          break;
        default:
          throw new IOException("channels");
      }

      int sampleSizeInBits = af.getSampleSizeInBits();
      int audioFormat;

      switch (sampleSizeInBits) {
        case 8:
          audioFormat = AudioFormat.ENCODING_PCM_8BIT;
          break;
        case 16:
          audioFormat = AudioFormat.ENCODING_PCM_16BIT;
          break;
        default:
          throw new IOException("sampleSizeInBits");
      }

      double sampleRate = af.getSampleRate();

      length =
          (int)
              Math.round(
                  20 /* milliseconds */ * (sampleRate / 1000) * channels * (sampleSizeInBits / 8));

      /*
       * Apart from the thread in which #read(Buffer) is executed, use the
       * thread priority for the thread which will create the AudioRecord.
       */
      setThreadPriority();
      try {
        int minBufferSize =
            AudioRecord.getMinBufferSize((int) sampleRate, channelConfig, audioFormat);

        audioRecord =
            new AudioRecord(
                MediaRecorder.AudioSource.DEFAULT,
                (int) sampleRate,
                channelConfig,
                audioFormat,
                Math.max(length, minBufferSize));

        // tries to configure audio effects if available
        configureEffects();
      } catch (IllegalArgumentException iae) {
        IOException ioe = new IOException();

        ioe.initCause(iae);
        throw ioe;
      }

      setThreadPriority = true;
    }