1 files changed, 138 insertions, 0 deletions
diff --git a/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/text/cea/CeaUtil.java b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/text/cea/CeaUtil.java
new file mode 100644
index 0000000000..ced169ba17
--- /dev/null
+++ b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/text/cea/CeaUtil.java
@@ -0,0 +1,138 @@
+/*
+ * Copyright (C) 2017 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 org.mozilla.thirdparty.com.google.android.exoplayer2.C;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.extractor.TrackOutput;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Log;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.ParsableByteArray;
+
+/** Utility methods for handling CEA-608/708 messages. Defined in A/53 Part 4:2009. */
+public final class CeaUtil {
+
+  private static final String TAG = "CeaUtil";
+
+  public static final int USER_DATA_IDENTIFIER_GA94 = 0x47413934;
+  public static final int USER_DATA_TYPE_CODE_MPEG_CC = 0x3;
+
+  private static final int PAYLOAD_TYPE_CC = 4;
+  private static final int COUNTRY_CODE = 0xB5;
+  private static final int PROVIDER_CODE_ATSC = 0x31;
+  private static final int PROVIDER_CODE_DIRECTV = 0x2F;
+
+  /**
+   * Consumes the unescaped content of an SEI NAL unit, writing the content of any CEA-608 messages
+   * as samples to all of the provided outputs.
+   *
+   * @param presentationTimeUs The presentation time in microseconds for any samples.
+   * @param seiBuffer The unescaped SEI NAL unit data, excluding the NAL unit start code and type.
+   * @param outputs The outputs to which any samples should be written.
+   */
+  public static void consume(long presentationTimeUs, ParsableByteArray seiBuffer,
+      TrackOutput[] outputs) {
+    while (seiBuffer.bytesLeft() > 1 /* last byte will be rbsp_trailing_bits */) {
+      int payloadType = readNon255TerminatedValue(seiBuffer);
+      int payloadSize = readNon255TerminatedValue(seiBuffer);
+      int nextPayloadPosition = seiBuffer.getPosition() + payloadSize;
+      // Process the payload.
+      if (payloadSize == -1 || payloadSize > seiBuffer.bytesLeft()) {
+        // This might occur if we're trying to read an encrypted SEI NAL unit.
+        Log.w(TAG, "Skipping remainder of malformed SEI NAL unit.");
+        nextPayloadPosition = seiBuffer.limit();
+      } else if (payloadType == PAYLOAD_TYPE_CC && payloadSize >= 8) {
+        int countryCode = seiBuffer.readUnsignedByte();
+        int providerCode = seiBuffer.readUnsignedShort();
+        int userIdentifier = 0;
+        if (providerCode == PROVIDER_CODE_ATSC) {
+          userIdentifier = seiBuffer.readInt();
+        }
+        int userDataTypeCode = seiBuffer.readUnsignedByte();
+        if (providerCode == PROVIDER_CODE_DIRECTV) {
+          seiBuffer.skipBytes(1); // user_data_length.
+        }
+        boolean messageIsSupportedCeaCaption =
+            countryCode == COUNTRY_CODE
+                && (providerCode == PROVIDER_CODE_ATSC || providerCode == PROVIDER_CODE_DIRECTV)
+                && userDataTypeCode == USER_DATA_TYPE_CODE_MPEG_CC;
+        if (providerCode == PROVIDER_CODE_ATSC) {
+          messageIsSupportedCeaCaption &= userIdentifier == USER_DATA_IDENTIFIER_GA94;
+        }
+        if (messageIsSupportedCeaCaption) {
+          consumeCcData(presentationTimeUs, seiBuffer, outputs);
+        }
+      }
+      seiBuffer.setPosition(nextPayloadPosition);
+    }
+  }
+
+  /**
+   * Consumes caption data (cc_data), writing the content as samples to all of the provided outputs.
+   *
+   * @param presentationTimeUs The presentation time in microseconds for any samples.
+   * @param ccDataBuffer The buffer containing the caption data.
+   * @param outputs The outputs to which any samples should be written.
+   */
+  public static void consumeCcData(
+      long presentationTimeUs, ParsableByteArray ccDataBuffer, TrackOutput[] outputs) {
+    // First byte contains: reserved (1), process_cc_data_flag (1), zero_bit (1), cc_count (5).
+    int firstByte = ccDataBuffer.readUnsignedByte();
+    boolean processCcDataFlag = (firstByte & 0x40) != 0;
+    if (!processCcDataFlag) {
+      // No need to process.
+      return;
+    }
+    int ccCount = firstByte & 0x1F;
+    ccDataBuffer.skipBytes(1); // Ignore em_data
+    // Each data packet consists of 24 bits: marker bits (5) + cc_valid (1) + cc_type (2)
+    // + cc_data_1 (8) + cc_data_2 (8).
+    int sampleLength = ccCount * 3;
+    int sampleStartPosition = ccDataBuffer.getPosition();
+    for (TrackOutput output : outputs) {
+      ccDataBuffer.setPosition(sampleStartPosition);
+      output.sampleData(ccDataBuffer, sampleLength);
+      output.sampleMetadata(
+          presentationTimeUs,
+          C.BUFFER_FLAG_KEY_FRAME,
+          sampleLength,
+          /* offset= */ 0,
+          /* encryptionData= */ null);
+    }
+  }
+
+  /**
+   * Reads a value from the provided buffer consisting of zero or more 0xFF bytes followed by a
+   * terminating byte not equal to 0xFF. The returned value is ((0xFF * N) + T), where N is the
+   * number of 0xFF bytes and T is the value of the terminating byte.
+   *
+   * @param buffer The buffer from which to read the value.
+   * @return The read value, or -1 if the end of the buffer is reached before a value is read.
+   */
+  private static int readNon255TerminatedValue(ParsableByteArray buffer) {
+    int b;
+    int value = 0;
+    do {
+      if (buffer.bytesLeft() == 0) {
+        return -1;
+      }
+      b = buffer.readUnsignedByte();
+      value += b;
+    } while (b == 0xFF);
+    return value;
+  }
+
+  private CeaUtil() {}
+
+}