content: /*
   * Copyright 2021 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 com.google.android.exoplayer2.metadata.mp4.SlowMotionData.Segment.BY_START_THEN_END_THEN_DIVISOR;
  import static com.google.android.exoplayer2.util.Assertions.checkArgument;
  
  import androidx.annotation.Nullable;
  import com.google.android.exoplayer2.C;
  import com.google.android.exoplayer2.Format;
  import com.google.android.exoplayer2.metadata.Metadata;
  import com.google.android.exoplayer2.metadata.mp4.SlowMotionData;
  import com.google.android.exoplayer2.metadata.mp4.SlowMotionData.Segment;
  import com.google.android.exoplayer2.metadata.mp4.SmtaMetadataEntry;
  import com.google.android.exoplayer2.util.Util;
  import com.google.common.collect.ImmutableList;
  import com.google.common.collect.ImmutableSortedMap;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Map;
  import java.util.TreeMap;
  
  /** A {@link SpeedProvider} for slow motion segments. */
  /* package */ class SegmentSpeedProvider implements SpeedProvider {
  
    /**
     * Input frame rate of Samsung Slow motion videos is always 30. See
     * go/exoplayer-sef-slomo-video-flattening.
     */
    private static final int INPUT_FRAME_RATE = 30;
  
    private final ImmutableSortedMap<Long, Float> speedsByStartTimeUs;
    private final float baseSpeedMultiplier;
  
    public SegmentSpeedProvider(Format format) {
      float captureFrameRate = getCaptureFrameRate(format);
      this.baseSpeedMultiplier =
          captureFrameRate == C.RATE_UNSET ? 1 : captureFrameRate / INPUT_FRAME_RATE;
      this.speedsByStartTimeUs = buildSpeedByStartTimeUsMap(format, baseSpeedMultiplier);
    }
  
    @Override
    public float getSpeed(long timeUs) {
      checkArgument(timeUs >= 0);
      @Nullable Map.Entry<Long, Float> entry = speedsByStartTimeUs.floorEntry(timeUs);
      return entry != null ? entry.getValue() : baseSpeedMultiplier;
    }
  
    @Override
    public long getNextSpeedChangeTimeUs(long timeUs) {
      checkArgument(timeUs >= 0);
      @Nullable Long nextTimeUs = speedsByStartTimeUs.higherKey(timeUs);
      return nextTimeUs != null ? nextTimeUs : C.TIME_UNSET;
    }
  
    private static ImmutableSortedMap<Long, Float> buildSpeedByStartTimeUsMap(
        Format format, float baseSpeed) {
      List<Segment> segments = extractSlowMotionSegments(format);
  
      if (segments.isEmpty()) {
        return ImmutableSortedMap.of();
      }
  
      TreeMap<Long, Float> speedsByStartTimeUs = new TreeMap<>();
  
      // Start time maps to the segment speed.
      for (int i = 0; i < segments.size(); i++) {
        Segment currentSegment = segments.get(i);
        speedsByStartTimeUs.put(
            Util.msToUs(currentSegment.startTimeMs), baseSpeed / currentSegment.speedDivisor);
      }
  
      // If the map has an entry at endTime, this is the next segments start time. If no such entry
      // exists, map the endTime to base speed because the times after the end time are not in a
      // segment.
      for (int i = 0; i < segments.size(); i++) {
        Segment currentSegment = segments.get(i);
        if (!speedsByStartTimeUs.containsKey(Util.msToUs(currentSegment.endTimeMs))) {
          speedsByStartTimeUs.put(Util.msToUs(currentSegment.endTimeMs), baseSpeed);
        }
      }
  
      return ImmutableSortedMap.copyOf(speedsByStartTimeUs);
    }
  
    private static float getCaptureFrameRate(Format format) {
      @Nullable Metadata metadata = format.metadata;
      if (metadata == null) {
        return C.RATE_UNSET;
      }
      for (int i = 0; i < metadata.length(); i++) {
        Metadata.Entry entry = metadata.get(i);
        if (entry instanceof SmtaMetadataEntry) {
          return ((SmtaMetadataEntry) entry).captureFrameRate;
        }
      }
  
      return C.RATE_UNSET;
    }
  
    private static ImmutableList<Segment> extractSlowMotionSegments(Format format) {
      List<Segment> segments = new ArrayList<>();
      @Nullable Metadata metadata = format.metadata;
      if (metadata != null) {
        for (int i = 0; i < metadata.length(); i++) {
          Metadata.Entry entry = metadata.get(i);
          if (entry instanceof SlowMotionData) {
            segments.addAll(((SlowMotionData) entry).segments);
          }
        }
      }
      return ImmutableList.sortedCopyOf(BY_START_THEN_END_THEN_DIVISOR, segments);
    }
  }
  