1 files changed, 84 insertions, 0 deletions
diff --git a/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/extractor/FlacSeekTableSeekMap.java b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/extractor/FlacSeekTableSeekMap.java
new file mode 100644
index 0000000000..56d54596ac
--- /dev/null
+++ b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/extractor/FlacSeekTableSeekMap.java
@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2019 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 org.mozilla.thirdparty.com.google.android.exoplayer2.extractor;
+
+import org.mozilla.thirdparty.com.google.android.exoplayer2.C;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Assertions;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.FlacStreamMetadata;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Util;
+
+/**
+ * A {@link SeekMap} implementation for FLAC streams that contain a <a
+ * href="https://xiph.org/flac/format.html#metadata_block_seektable">seek table</a>.
+ */
+public final class FlacSeekTableSeekMap implements SeekMap {
+
+  private final FlacStreamMetadata flacStreamMetadata;
+  private final long firstFrameOffset;
+
+  /**
+   * Creates a seek map from the FLAC stream seek table.
+   *
+   * @param flacStreamMetadata The stream metadata.
+   * @param firstFrameOffset The byte offset of the first frame in the stream.
+   */
+  public FlacSeekTableSeekMap(FlacStreamMetadata flacStreamMetadata, long firstFrameOffset) {
+    this.flacStreamMetadata = flacStreamMetadata;
+    this.firstFrameOffset = firstFrameOffset;
+  }
+
+  @Override
+  public boolean isSeekable() {
+    return true;
+  }
+
+  @Override
+  public long getDurationUs() {
+    return flacStreamMetadata.getDurationUs();
+  }
+
+  @Override
+  public SeekPoints getSeekPoints(long timeUs) {
+    Assertions.checkNotNull(flacStreamMetadata.seekTable);
+    long[] pointSampleNumbers = flacStreamMetadata.seekTable.pointSampleNumbers;
+    long[] pointOffsets = flacStreamMetadata.seekTable.pointOffsets;
+
+    long targetSampleNumber = flacStreamMetadata.getSampleNumber(timeUs);
+    int index =
+        Util.binarySearchFloor(
+            pointSampleNumbers,
+            targetSampleNumber,
+            /* inclusive= */ true,
+            /* stayInBounds= */ false);
+
+    long seekPointSampleNumber = index == -1 ? 0 : pointSampleNumbers[index];
+    long seekPointOffsetFromFirstFrame = index == -1 ? 0 : pointOffsets[index];
+    SeekPoint seekPoint = getSeekPoint(seekPointSampleNumber, seekPointOffsetFromFirstFrame);
+    if (seekPoint.timeUs == timeUs || index == pointSampleNumbers.length - 1) {
+      return new SeekPoints(seekPoint);
+    } else {
+      SeekPoint secondSeekPoint =
+          getSeekPoint(pointSampleNumbers[index + 1], pointOffsets[index + 1]);
+      return new SeekPoints(seekPoint, secondSeekPoint);
+    }
+  }
+
+  private SeekPoint getSeekPoint(long sampleNumber, long offsetFromFirstFrame) {
+    long seekTimeUs = sampleNumber * C.MICROS_PER_SECOND / flacStreamMetadata.sampleRate;
+    long seekPosition = firstFrameOffset + offsetFromFirstFrame;
+    return new SeekPoint(seekTimeUs, seekPosition);
+  }
+}