1 files changed, 197 insertions, 0 deletions
diff --git a/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/extractor/ts/TsDurationReader.java b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/extractor/ts/TsDurationReader.java
new file mode 100644
index 0000000000..ed4b66a7e4
--- /dev/null
+++ b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/extractor/ts/TsDurationReader.java
@@ -0,0 +1,197 @@
+/*
+ * Copyright (C) 2018 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.ts;
+
+import org.mozilla.thirdparty.com.google.android.exoplayer2.C;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.extractor.Extractor;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.extractor.ExtractorInput;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.extractor.PositionHolder;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.ParsableByteArray;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.TimestampAdjuster;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Util;
+import java.io.IOException;
+
+/**
+ * A reader that can extract the approximate duration from a given MPEG transport stream (TS).
+ *
+ * <p>This reader extracts the duration by reading PCR values of the PCR PID packets at the start
+ * and at the end of the stream, calculating the difference, and converting that into stream
+ * duration. This reader also handles the case when a single PCR wraparound takes place within the
+ * stream, which can make PCR values at the beginning of the stream larger than PCR values at the
+ * end. This class can only be used once to read duration from a given stream, and the usage of the
+ * class is not thread-safe, so all calls should be made from the same thread.
+ */
+/* package */ final class TsDurationReader {
+
+  private static final int TIMESTAMP_SEARCH_BYTES = 600 * TsExtractor.TS_PACKET_SIZE;
+
+  private final TimestampAdjuster pcrTimestampAdjuster;
+  private final ParsableByteArray packetBuffer;
+
+  private boolean isDurationRead;
+  private boolean isFirstPcrValueRead;
+  private boolean isLastPcrValueRead;
+
+  private long firstPcrValue;
+  private long lastPcrValue;
+  private long durationUs;
+
+  /* package */ TsDurationReader() {
+    pcrTimestampAdjuster = new TimestampAdjuster(/* firstSampleTimestampUs= */ 0);
+    firstPcrValue = C.TIME_UNSET;
+    lastPcrValue = C.TIME_UNSET;
+    durationUs = C.TIME_UNSET;
+    packetBuffer = new ParsableByteArray();
+  }
+
+  /** Returns true if a TS duration has been read. */
+  public boolean isDurationReadFinished() {
+    return isDurationRead;
+  }
+
+  /**
+   * Reads a TS duration from the input, using the given PCR PID.
+   *
+   * <p>This reader reads the duration by reading PCR values of the PCR PID packets at the start and
+   * at the end of the stream, calculating the difference, and converting that into stream duration.
+   *
+   * @param input The {@link ExtractorInput} from which data should be read.
+   * @param seekPositionHolder If {@link Extractor#RESULT_SEEK} is returned, this holder is updated
+   *     to hold the position of the required seek.
+   * @param pcrPid The PID of the packet stream within this TS stream that contains PCR values.
+   * @return One of the {@code RESULT_} values defined in {@link Extractor}.
+   * @throws IOException If an error occurred reading from the input.
+   * @throws InterruptedException If the thread was interrupted.
+   */
+  public @Extractor.ReadResult int readDuration(
+      ExtractorInput input, PositionHolder seekPositionHolder, int pcrPid)
+      throws IOException, InterruptedException {
+    if (pcrPid <= 0) {
+      return finishReadDuration(input);
+    }
+    if (!isLastPcrValueRead) {
+      return readLastPcrValue(input, seekPositionHolder, pcrPid);
+    }
+    if (lastPcrValue == C.TIME_UNSET) {
+      return finishReadDuration(input);
+    }
+    if (!isFirstPcrValueRead) {
+      return readFirstPcrValue(input, seekPositionHolder, pcrPid);
+    }
+    if (firstPcrValue == C.TIME_UNSET) {
+      return finishReadDuration(input);
+    }
+
+    long minPcrPositionUs = pcrTimestampAdjuster.adjustTsTimestamp(firstPcrValue);
+    long maxPcrPositionUs = pcrTimestampAdjuster.adjustTsTimestamp(lastPcrValue);
+    durationUs = maxPcrPositionUs - minPcrPositionUs;
+    return finishReadDuration(input);
+  }
+
+  /**
+   * Returns the duration last read from {@link #readDuration(ExtractorInput, PositionHolder, int)}.
+   */
+  public long getDurationUs() {
+    return durationUs;
+  }
+
+  /**
+   * Returns the {@link TimestampAdjuster} that this class uses to adjust timestamps read from the
+   * input TS stream.
+   */
+  public TimestampAdjuster getPcrTimestampAdjuster() {
+    return pcrTimestampAdjuster;
+  }
+
+  private int finishReadDuration(ExtractorInput input) {
+    packetBuffer.reset(Util.EMPTY_BYTE_ARRAY);
+    isDurationRead = true;
+    input.resetPeekPosition();
+    return Extractor.RESULT_CONTINUE;
+  }
+
+  private int readFirstPcrValue(ExtractorInput input, PositionHolder seekPositionHolder, int pcrPid)
+      throws IOException, InterruptedException {
+    int bytesToSearch = (int) Math.min(TIMESTAMP_SEARCH_BYTES, input.getLength());
+    int searchStartPosition = 0;
+    if (input.getPosition() != searchStartPosition) {
+      seekPositionHolder.position = searchStartPosition;
+      return Extractor.RESULT_SEEK;
+    }
+
+    packetBuffer.reset(bytesToSearch);
+    input.resetPeekPosition();
+    input.peekFully(packetBuffer.data, /* offset= */ 0, bytesToSearch);
+
+    firstPcrValue = readFirstPcrValueFromBuffer(packetBuffer, pcrPid);
+    isFirstPcrValueRead = true;
+    return Extractor.RESULT_CONTINUE;
+  }
+
+  private long readFirstPcrValueFromBuffer(ParsableByteArray packetBuffer, int pcrPid) {
+    int searchStartPosition = packetBuffer.getPosition();
+    int searchEndPosition = packetBuffer.limit();
+    for (int searchPosition = searchStartPosition;
+        searchPosition < searchEndPosition;
+        searchPosition++) {
+      if (packetBuffer.data[searchPosition] != TsExtractor.TS_SYNC_BYTE) {
+        continue;
+      }
+      long pcrValue = TsUtil.readPcrFromPacket(packetBuffer, searchPosition, pcrPid);
+      if (pcrValue != C.TIME_UNSET) {
+        return pcrValue;
+      }
+    }
+    return C.TIME_UNSET;
+  }
+
+  private int readLastPcrValue(ExtractorInput input, PositionHolder seekPositionHolder, int pcrPid)
+      throws IOException, InterruptedException {
+    long inputLength = input.getLength();
+    int bytesToSearch = (int) Math.min(TIMESTAMP_SEARCH_BYTES, inputLength);
+    long searchStartPosition = inputLength - bytesToSearch;
+    if (input.getPosition() != searchStartPosition) {
+      seekPositionHolder.position = searchStartPosition;
+      return Extractor.RESULT_SEEK;
+    }
+
+    packetBuffer.reset(bytesToSearch);
+    input.resetPeekPosition();
+    input.peekFully(packetBuffer.data, /* offset= */ 0, bytesToSearch);
+
+    lastPcrValue = readLastPcrValueFromBuffer(packetBuffer, pcrPid);
+    isLastPcrValueRead = true;
+    return Extractor.RESULT_CONTINUE;
+  }
+
+  private long readLastPcrValueFromBuffer(ParsableByteArray packetBuffer, int pcrPid) {
+    int searchStartPosition = packetBuffer.getPosition();
+    int searchEndPosition = packetBuffer.limit();
+    for (int searchPosition = searchEndPosition - 1;
+        searchPosition >= searchStartPosition;
+        searchPosition--) {
+      if (packetBuffer.data[searchPosition] != TsExtractor.TS_SYNC_BYTE) {
+        continue;
+      }
+      long pcrValue = TsUtil.readPcrFromPacket(packetBuffer, searchPosition, pcrPid);
+      if (pcrValue != C.TIME_UNSET) {
+        return pcrValue;
+      }
+    }
+    return C.TIME_UNSET;
+  }
+
+}