androidx · rahulnmohan · Mar 22, 2023 · Mar 27, 2023 · Apr 4, 2023 · Apr 10, 2023
diff --git a/RELEASENOTES.md b/RELEASENOTES.md
@@ -142,6 +142,8 @@ This release includes the following changes since
  inspected with `instanceof`. If you want runtime access to the
  implementation details of an `Extractor` you must first call
  `Extractor.getUnderlyingInstance`.
+ * MPEG2-TS: Add DTS, DTS-LBR and DTS:X Profile2 support
+ ([#275](https://github.com/androidx/media/pull/275)).
 * Audio:
  * Add support for 24/32-bit big-endian PCM in MP4 and Matroska, and parse
  PCM encoding for `lpcm` in MP4.

diff --git a/libraries/common/src/main/java/androidx/media3/common/util/Util.java b/libraries/common/src/main/java/androidx/media3/common/util/Util.java
@@ -2627,6 +2627,46 @@ public static int crc32(byte[] bytes, int start, int end, int initialValue) {
  return initialValue;
  }
 
+ /**
+ * Returns the result of updating a CRC-16 with the specified bytes in a "most significant bit
+ * first" order.
+ *
+ * @param bytes Array containing the bytes to update the crc value with.
+ * @param start The index to the first byte in the byte range to update the crc with.
+ * @param end The index after the last byte in the byte range to update the crc with.
+ * @param initialValue The initial value for the crc calculation.
+ * @return The result of updating the initial value with the specified bytes.
+ */
+ @UnstableApi
+ public static int crc16(byte[] bytes, int start, int end, int initialValue) {
+ for (int i = start; i < end; i++) {
+ short value = (short) (bytes[i] & 0xFF);
+ // Process one message byte to update the current CRC-16 value.
+ initialValue = crc16UpdateFourBits((short) (value >> 4), initialValue); // High nibble first.
+ initialValue = crc16UpdateFourBits((short) (value & 0x0F), initialValue); // Low nibble.
+ }
+ return initialValue;
+ }
+
+ /**
+ * Process 4 bits of the message to update the CRC Value. Note that the data will be in the low
+ * nibble of val.
+ */
+ private static int crc16UpdateFourBits(short val, int crc16Register) {
+ short t; // This will be handled as unsigned 8 bit data.
+
+ // Step one, extract the most significant 4 bits of the CRC register.
+ t = (short) ((crc16Register >> 12) & 0xFF);
+ // XOR in the Message Data into the extracted bits.
+ t = (short) ((t ^ val) & 0xFF);
+ // Shift the CRC register left 4 bits.
+ crc16Register = (crc16Register << 4) & 0xFFFF; // Handle as 16 bit, discard any sign extension.
+ // Do the table look-ups and XOR the result into the CRC tables.
+ crc16Register = (crc16Register ^ CRC16_BYTES_MSBF[t]) & 0xFFFF;
+
+ return crc16Register;
+ }
+
  /**
  * Returns the result of updating a CRC-8 with the specified bytes in a "most significant bit
  * first" order.
@@ -3511,6 +3551,16 @@ private static String maybeReplaceLegacyLanguageTags(String languageTag) {
  0XBCB4666D, 0XB8757BDA, 0XB5365D03, 0XB1F740B4
  };
 
+ /**
+ * Allows the CRC-16 calculation to be done byte by byte instead of bit per bit in the order "most
+ * significant bit first".
+ */
+ private static final int[] CRC16_BYTES_MSBF =
+ new int[] {
+ 0x0000, 0x01021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7,
+ 0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF
+ };
+
  /**
  * Allows the CRC-8 calculation to be done byte by byte instead of bit per bit in the order "most
  * significant bit first".