content: /*
   * Copyright 2022 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com.google.android.exoplayer2.transformer;
  
  import static java.lang.Math.min;
  
  import com.google.android.exoplayer2.C;
  import com.google.android.exoplayer2.audio.AudioProcessor;
  import com.google.android.exoplayer2.audio.BaseAudioProcessor;
  import com.google.android.exoplayer2.audio.SonicAudioProcessor;
  import com.google.android.exoplayer2.util.Util;
  import com.google.errorprone.annotations.CanIgnoreReturnValue;
  import java.nio.ByteBuffer;
  
  /**
   * An {@link AudioProcessor} that changes the speed of audio samples depending on their timestamp.
   */
  // TODO(b/198772621): Consider making the processor inactive and skipping it in the processor chain
  //  when speed is 1.
  /* package */ final class SpeedChangingAudioProcessor extends BaseAudioProcessor {
  
    /** The speed provider that provides the speed for each timestamp. */
    private final SpeedProvider speedProvider;
    /**
     * The {@link SonicAudioProcessor} used to change the speed, when needed. If there is no speed
     * change required, the input buffer is copied to the output buffer and this processor is not
     * used.
     */
    private final SonicAudioProcessor sonicAudioProcessor;
  
    private float currentSpeed;
    private long bytesRead;
    private boolean endOfStreamQueuedToSonic;
  
    public SpeedChangingAudioProcessor(SpeedProvider speedProvider) {
      this.speedProvider = speedProvider;
      sonicAudioProcessor = new SonicAudioProcessor();
      currentSpeed = 1f;
    }
  
    @Override
    @CanIgnoreReturnValue
    public AudioFormat onConfigure(AudioFormat inputAudioFormat)
        throws UnhandledAudioFormatException {
      return sonicAudioProcessor.configure(inputAudioFormat);
    }
  
    @Override
    public void queueInput(ByteBuffer inputBuffer) {
      long timeUs =
          Util.scaleLargeTimestamp(
              /* timestamp= */ bytesRead,
              /* multiplier= */ C.MICROS_PER_SECOND,
              /* divisor= */ (long) inputAudioFormat.sampleRate * inputAudioFormat.bytesPerFrame);
      float newSpeed = speedProvider.getSpeed(timeUs);
      if (newSpeed != currentSpeed) {
        currentSpeed = newSpeed;
        if (isUsingSonic()) {
          sonicAudioProcessor.setSpeed(newSpeed);
          sonicAudioProcessor.setPitch(newSpeed);
        }
        flush();
      }
  
      int inputBufferLimit = inputBuffer.limit();
      long nextSpeedChangeTimeUs = speedProvider.getNextSpeedChangeTimeUs(timeUs);
      int bytesToNextSpeedChange;
      if (nextSpeedChangeTimeUs != C.TIME_UNSET) {
        bytesToNextSpeedChange =
            (int)
                Util.scaleLargeTimestamp(
                    /* timestamp= */ nextSpeedChangeTimeUs - timeUs,
                    /* multiplier= */ (long) inputAudioFormat.sampleRate
                        * inputAudioFormat.bytesPerFrame,
                    /* divisor= */ C.MICROS_PER_SECOND);
        int bytesToNextFrame =
            inputAudioFormat.bytesPerFrame - bytesToNextSpeedChange % inputAudioFormat.bytesPerFrame;
        if (bytesToNextFrame != inputAudioFormat.bytesPerFrame) {
          bytesToNextSpeedChange += bytesToNextFrame;
        }
        // Update the input buffer limit to make sure that all samples processed have the same speed.
        inputBuffer.limit(min(inputBufferLimit, inputBuffer.position() + bytesToNextSpeedChange));
      } else {
        bytesToNextSpeedChange = C.LENGTH_UNSET;
      }
  
      long startPosition = inputBuffer.position();
      if (isUsingSonic()) {
        sonicAudioProcessor.queueInput(inputBuffer);
        if (bytesToNextSpeedChange != C.LENGTH_UNSET
            && (inputBuffer.position() - startPosition) == bytesToNextSpeedChange) {
          sonicAudioProcessor.queueEndOfStream();
          endOfStreamQueuedToSonic = true;
        }
      } else {
        ByteBuffer buffer = replaceOutputBuffer(/* size= */ inputBuffer.remaining());
        buffer.put(inputBuffer);
        buffer.flip();
      }
      bytesRead += inputBuffer.position() - startPosition;
      inputBuffer.limit(inputBufferLimit);
    }
  
    @Override
    protected void onQueueEndOfStream() {
      if (!endOfStreamQueuedToSonic) {
        sonicAudioProcessor.queueEndOfStream();
        endOfStreamQueuedToSonic = true;
      }
    }
  
    @Override
    public ByteBuffer getOutput() {
      return isUsingSonic() ? sonicAudioProcessor.getOutput() : super.getOutput();
    }
  
    @Override
    public boolean isEnded() {
      return super.isEnded() && sonicAudioProcessor.isEnded();
    }
  
    @Override
    protected void onFlush() {
      sonicAudioProcessor.flush();
      endOfStreamQueuedToSonic = false;
    }
  
    @Override
    protected void onReset() {
      currentSpeed = 1f;
      bytesRead = 0;
      sonicAudioProcessor.reset();
      endOfStreamQueuedToSonic = false;
    }
  
    private boolean isUsingSonic() {
      return currentSpeed != 1f;
    }
  }
  