1 files changed, 204 insertions, 0 deletions
diff --git a/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/text/cea/CeaDecoder.java b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/text/cea/CeaDecoder.java
new file mode 100644
index 0000000000..42fa915fc5
--- /dev/null
+++ b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/text/cea/CeaDecoder.java
@@ -0,0 +1,204 @@
+/*
+ * Copyright (C) 2016 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.text.cea;
+
+import androidx.annotation.NonNull;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.C;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.Format;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.text.Subtitle;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.text.SubtitleDecoder;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.text.SubtitleDecoderException;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.text.SubtitleInputBuffer;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.text.SubtitleOutputBuffer;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Assertions;
+import java.util.ArrayDeque;
+import java.util.PriorityQueue;
+
+/**
+ * Base class for subtitle parsers for CEA captions.
+ */
+/* package */ abstract class CeaDecoder implements SubtitleDecoder {
+
+  private static final int NUM_INPUT_BUFFERS = 10;
+  private static final int NUM_OUTPUT_BUFFERS = 2;
+
+  private final ArrayDeque<CeaInputBuffer> availableInputBuffers;
+  private final ArrayDeque<SubtitleOutputBuffer> availableOutputBuffers;
+  private final PriorityQueue<CeaInputBuffer> queuedInputBuffers;
+
+  private CeaInputBuffer dequeuedInputBuffer;
+  private long playbackPositionUs;
+  private long queuedInputBufferCount;
+
+  public CeaDecoder() {
+    availableInputBuffers = new ArrayDeque<>();
+    for (int i = 0; i < NUM_INPUT_BUFFERS; i++) {
+      availableInputBuffers.add(new CeaInputBuffer());
+    }
+    availableOutputBuffers = new ArrayDeque<>();
+    for (int i = 0; i < NUM_OUTPUT_BUFFERS; i++) {
+      availableOutputBuffers.add(new CeaOutputBuffer());
+    }
+    queuedInputBuffers = new PriorityQueue<>();
+  }
+
+  @Override
+  public abstract String getName();
+
+  @Override
+  public void setPositionUs(long positionUs) {
+    playbackPositionUs = positionUs;
+  }
+
+  @Override
+  public SubtitleInputBuffer dequeueInputBuffer() throws SubtitleDecoderException {
+    Assertions.checkState(dequeuedInputBuffer == null);
+    if (availableInputBuffers.isEmpty()) {
+      return null;
+    }
+    dequeuedInputBuffer = availableInputBuffers.pollFirst();
+    return dequeuedInputBuffer;
+  }
+
+  @Override
+  public void queueInputBuffer(SubtitleInputBuffer inputBuffer) throws SubtitleDecoderException {
+    Assertions.checkArgument(inputBuffer == dequeuedInputBuffer);
+    if (inputBuffer.isDecodeOnly()) {
+      // We can drop this buffer early (i.e. before it would be decoded) as the CEA formats allow
+      // for decoding to begin mid-stream.
+      releaseInputBuffer(dequeuedInputBuffer);
+    } else {
+      dequeuedInputBuffer.queuedInputBufferCount = queuedInputBufferCount++;
+      queuedInputBuffers.add(dequeuedInputBuffer);
+    }
+    dequeuedInputBuffer = null;
+  }
+
+  @Override
+  public SubtitleOutputBuffer dequeueOutputBuffer() throws SubtitleDecoderException {
+    if (availableOutputBuffers.isEmpty()) {
+      return null;
+    }
+    // iterate through all available input buffers whose timestamps are less than or equal
+    // to the current playback position; processing input buffers for future content should
+    // be deferred until they would be applicable
+    while (!queuedInputBuffers.isEmpty()
+        && queuedInputBuffers.peek().timeUs <= playbackPositionUs) {
+      CeaInputBuffer inputBuffer = queuedInputBuffers.poll();
+
+      // If the input buffer indicates we've reached the end of the stream, we can
+      // return immediately with an output buffer propagating that
+      if (inputBuffer.isEndOfStream()) {
+        SubtitleOutputBuffer outputBuffer = availableOutputBuffers.pollFirst();
+        outputBuffer.addFlag(C.BUFFER_FLAG_END_OF_STREAM);
+        releaseInputBuffer(inputBuffer);
+        return outputBuffer;
+      }
+
+      decode(inputBuffer);
+
+      // check if we have any caption updates to report
+      if (isNewSubtitleDataAvailable()) {
+        // Even if the subtitle is decode-only; we need to generate it to consume the data so it
+        // isn't accidentally prepended to the next subtitle
+        Subtitle subtitle = createSubtitle();
+        if (!inputBuffer.isDecodeOnly()) {
+          SubtitleOutputBuffer outputBuffer = availableOutputBuffers.pollFirst();
+          outputBuffer.setContent(inputBuffer.timeUs, subtitle, Format.OFFSET_SAMPLE_RELATIVE);
+          releaseInputBuffer(inputBuffer);
+          return outputBuffer;
+        }
+      }
+
+      releaseInputBuffer(inputBuffer);
+    }
+
+    return null;
+  }
+
+  private void releaseInputBuffer(CeaInputBuffer inputBuffer) {
+    inputBuffer.clear();
+    availableInputBuffers.add(inputBuffer);
+  }
+
+  protected void releaseOutputBuffer(SubtitleOutputBuffer outputBuffer) {
+    outputBuffer.clear();
+    availableOutputBuffers.add(outputBuffer);
+  }
+
+  @Override
+  public void flush() {
+    queuedInputBufferCount = 0;
+    playbackPositionUs = 0;
+    while (!queuedInputBuffers.isEmpty()) {
+      releaseInputBuffer(queuedInputBuffers.poll());
+    }
+    if (dequeuedInputBuffer != null) {
+      releaseInputBuffer(dequeuedInputBuffer);
+      dequeuedInputBuffer = null;
+    }
+  }
+
+  @Override
+  public void release() {
+    // Do nothing
+  }
+
+  /**
+   * Returns whether there is data available to create a new {@link Subtitle}.
+   */
+  protected abstract boolean isNewSubtitleDataAvailable();
+
+  /**
+   * Creates a {@link Subtitle} from the available data.
+   */
+  protected abstract Subtitle createSubtitle();
+
+  /**
+   * Filters and processes the raw data, providing {@link Subtitle}s via {@link #createSubtitle()}
+   * when sufficient data has been processed.
+   */
+  protected abstract void decode(SubtitleInputBuffer inputBuffer);
+
+  private static final class CeaInputBuffer extends SubtitleInputBuffer
+      implements Comparable<CeaInputBuffer> {
+
+    private long queuedInputBufferCount;
+
+    @Override
+    public int compareTo(@NonNull CeaInputBuffer other) {
+      if (isEndOfStream() != other.isEndOfStream()) {
+        return isEndOfStream() ? 1 : -1;
+      }
+      long delta = timeUs - other.timeUs;
+      if (delta == 0) {
+        delta = queuedInputBufferCount - other.queuedInputBufferCount;
+        if (delta == 0) {
+          return 0;
+        }
+      }
+      return delta > 0 ? 1 : -1;
+    }
+  }
+
+  private final class CeaOutputBuffer extends SubtitleOutputBuffer {
+
+    @Override
+    public final void release() {
+      releaseOutputBuffer(this);
+    }
+  }
+}