Add support for reading AC-3 audio in HLS.

library/src/main/java/com/google/android/exoplayer/extractor/ts/Ac3Reader.java

+/*
+ * Copyright (C) 2014 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 com.google.android.exoplayer.extractor.ts;
+
+import com.google.android.exoplayer.C;
+import com.google.android.exoplayer.MediaFormat;
+import com.google.android.exoplayer.extractor.TrackOutput;
+import com.google.android.exoplayer.util.Ac3Util;
+import com.google.android.exoplayer.util.ParsableBitArray;
+import com.google.android.exoplayer.util.ParsableByteArray;
+
+/**
+ * Parses a continuous AC-3 byte stream and extracts individual samples.
+ */
+/* package */ final class Ac3Reader extends ElementaryStreamReader {
+
+  private static final int STATE_FINDING_SYNC = 0;
+  private static final int STATE_READING_HEADER = 1;
+  private static final int STATE_READING_SAMPLE = 2;
+
+  private static final int HEADER_SIZE = 8;
+
+  private final ParsableBitArray headerScratchBits;
+  private final ParsableByteArray headerScratchBytes;
+
+  private int state;
+  private int bytesRead;
+
+  // Used to find the header.
+  private boolean lastByteWas0B;
+
+  // Used when parsing the header.
+  private long frameDurationUs;
+  private MediaFormat mediaFormat;
+  private int sampleSize;
+
+  // Used when reading the samples.
+  private long timeUs;
+
+  public Ac3Reader(TrackOutput output) {
+    super(output);
+    headerScratchBits = new ParsableBitArray(new byte[HEADER_SIZE]);
+    headerScratchBytes = new ParsableByteArray(headerScratchBits.getData());
+    state = STATE_FINDING_SYNC;
+  }
+
+  public void seek() {
+    state = STATE_FINDING_SYNC;
+    bytesRead = 0;
+    lastByteWas0B = false;
+  }
+
+  @Override
+  public void consume(ParsableByteArray data, long pesTimeUs, boolean startOfPacket) {
+    if (startOfPacket) {
+      timeUs = pesTimeUs;
+    }
+    while (data.bytesLeft() > 0) {
+      switch (state) {
+        case STATE_FINDING_SYNC:
+          if (skipToNextSync(data)) {
+            state = STATE_READING_HEADER;
+            headerScratchBytes.data[0] = 0x0B;
+            headerScratchBytes.data[1] = 0x77;
+            bytesRead = 2;
+          }
+          break;
+        case STATE_READING_HEADER:
+          if (continueRead(data, headerScratchBytes.data, HEADER_SIZE)) {
+            parseHeader();
+            headerScratchBytes.setPosition(0);
+            output.sampleData(headerScratchBytes, HEADER_SIZE);
+            state = STATE_READING_SAMPLE;
+          }
+          break;
+        case STATE_READING_SAMPLE:
+          int bytesToRead = Math.min(data.bytesLeft(), sampleSize - bytesRead);
+          output.sampleData(data, bytesToRead);
+          bytesRead += bytesToRead;
+          if (bytesRead == sampleSize) {
+            output.sampleMetadata(timeUs, C.SAMPLE_FLAG_SYNC, sampleSize, 0, null);
+            timeUs += frameDurationUs;
+            state = STATE_FINDING_SYNC;
+          }
+          break;
+      }
+    }
+  }
+
+  @Override
+  public void packetFinished() {
+    // Do nothing.
+  }
+
+  /**
+   * Continues a read from the provided {@code source} into a given {@code target}. It's assumed
+   * that the data should be written into {@code target} starting from an offset of zero.
+   *
+   * @param source The source from which to read.
+   * @param target The target into which data is to be read.
+   * @param targetLength The target length of the read.
+   * @return Whether the target length was reached.
+   */
+  private boolean continueRead(ParsableByteArray source, byte[] target, int targetLength) {
+    int bytesToRead = Math.min(source.bytesLeft(), targetLength - bytesRead);
+    source.readBytes(target, bytesRead, bytesToRead);
+    bytesRead += bytesToRead;
+    return bytesRead == targetLength;
+  }
+
+  /**
+   * Locates the next sync word, advancing the position to the byte that immediately follows it.
+   * If a sync word was not located, the position is advanced to the limit.
+   *
+   * @param pesBuffer The buffer whose position should be advanced.
+   * @return True if a sync word position was found. False otherwise.
+   */
+  private boolean skipToNextSync(ParsableByteArray pesBuffer) {
+    while (pesBuffer.bytesLeft() > 0) {
+      if (!lastByteWas0B) {
+        lastByteWas0B = pesBuffer.readUnsignedByte() == 0x0B;
+        continue;
+      }
+      int secondByte = pesBuffer.readUnsignedByte();
+      if (secondByte == 0x77) {
+        lastByteWas0B = false;
+        return true;
+      } else {
+        lastByteWas0B = secondByte == 0x0B;
+      }
+    }
+    return false;
+  }
+
+  /**
+   * Parses the sample header.
+   */
+  private void parseHeader() {
+    if (mediaFormat == null) {
+      headerScratchBits.setPosition(0);
+      mediaFormat = Ac3Util.parseFrameAc3Format(headerScratchBits);
+      output.format(mediaFormat);
+    }
+    headerScratchBits.setPosition(0);
+    sampleSize = Ac3Util.parseFrameSize(headerScratchBits);
+    frameDurationUs = (int) (1000000L * 8 * sampleSize / mediaFormat.bitrate);
+  }
+
+}

library/src/main/java/com/google/android/exoplayer/extractor/ts/TsExtractor.java

@@ -40,6 +40,8 @@ public final class TsExtractor implements Extractor {
   private static final int TS_PAT_PID = 0;
   private static final int TS_PAT_PID = 0;
 
 
   private static final int TS_STREAM_TYPE_AAC = 0x0F;
   private static final int TS_STREAM_TYPE_AAC = 0x0F;
+  private static final int TS_STREAM_TYPE_ATSC_AC3 = 0x81;
+  private static final int TS_STREAM_TYPE_DVB_AC3 = 0x06;
   private static final int TS_STREAM_TYPE_H264 = 0x1B;
   private static final int TS_STREAM_TYPE_H264 = 0x1B;
   private static final int TS_STREAM_TYPE_ID3 = 0x15;
   private static final int TS_STREAM_TYPE_ID3 = 0x15;
   private static final int TS_STREAM_TYPE_EIA608 = 0x100; // 0xFF + 1
   private static final int TS_STREAM_TYPE_EIA608 = 0x100; // 0xFF + 1
@@ -262,11 +264,14 @@ public final class TsExtractor implements Extractor {
           case TS_STREAM_TYPE_AAC:
           case TS_STREAM_TYPE_AAC:
             pesPayloadReader = new AdtsReader(output.track(TS_STREAM_TYPE_AAC));
             pesPayloadReader = new AdtsReader(output.track(TS_STREAM_TYPE_AAC));
             break;
             break;
+          case TS_STREAM_TYPE_ATSC_AC3:
+          case TS_STREAM_TYPE_DVB_AC3:
+            pesPayloadReader = new Ac3Reader(output.track(streamType));
+            break;
           case TS_STREAM_TYPE_H264:
           case TS_STREAM_TYPE_H264:
             SeiReader seiReader = new SeiReader(output.track(TS_STREAM_TYPE_EIA608));
             SeiReader seiReader = new SeiReader(output.track(TS_STREAM_TYPE_EIA608));
             streamReaders.put(TS_STREAM_TYPE_EIA608, seiReader);
             streamReaders.put(TS_STREAM_TYPE_EIA608, seiReader);
-            pesPayloadReader = new H264Reader(output.track(TS_STREAM_TYPE_H264),
-                seiReader);
+            pesPayloadReader = new H264Reader(output.track(TS_STREAM_TYPE_H264), seiReader);
             break;
             break;
           case TS_STREAM_TYPE_ID3:
           case TS_STREAM_TYPE_ID3:
             pesPayloadReader = id3Reader;
             pesPayloadReader = id3Reader;

library/src/main/java/com/google/android/exoplayer/util/Ac3Util.java

+/*
+ * Copyright (C) 2014 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 com.google.android.exoplayer.util;
+
+import com.google.android.exoplayer.MediaFormat;
+
+import java.util.Collections;
+
+/**
+ * Utility methods for parsing AC-3 headers.
+ */
+public final class Ac3Util {
+
+  /** Sample rates, indexed by fscod. */
+  private static final int[] SAMPLE_RATES = new int[] {48000, 44100, 32000};
+  /** Channel counts, indexed by acmod. */
+  private static final int[] CHANNEL_COUNTS = new int[] {2, 1, 2, 3, 3, 4, 4, 5};
+  /** Nominal bitrates in kbps, indexed by bit_rate_code. */
+  private static final int[] BITRATES = new int[] {32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192,
+      224, 256, 320, 384, 448, 512, 576, 640};
+  /** 16-bit words per sync frame, indexed by frmsizecod / 2. (See ETSI TS 102 366 table 4.13.) */
+  private static final int[] FRMSIZECOD_TO_FRAME_SIZE_44_1 = new int[] {69, 87, 104, 121, 139, 174,
+    208, 243, 278, 348, 417, 487, 557, 696, 835, 975, 1114, 1253, 1393};
+
+  /**
+   * Returns the AC-3 format given {@code data} containing the AC3SpecificBox according to
+   * ETSI TS 102 366 Annex F.
+   */
+  public static MediaFormat parseAnnexFAc3Format(ParsableByteArray data) {
+    // fscod (sample rate code)
+    int fscod = (data.readUnsignedByte() & 0xC0) >> 6;
+    int sampleRate = SAMPLE_RATES[fscod];
+    int nextByte = data.readUnsignedByte();
+    // Map acmod (audio coding mode) onto a channel count.
+    int channelCount = CHANNEL_COUNTS[(nextByte & 0x38) >> 3];
+    // lfeon (low frequency effects on)
+    if ((nextByte & 0x04) != 0) {
+      channelCount++;
+    }
+    // Map bit_rate_code onto a bitrate in bit/s.
+    int bitrate = BITRATES[((nextByte & 0x03) << 3) + (data.readUnsignedByte() >> 5)] * 1000;
+    return MediaFormat.createAudioFormat(MimeTypes.AUDIO_AC3, MediaFormat.NO_VALUE,
+        MediaFormat.NO_VALUE, channelCount, sampleRate, bitrate, Collections.<byte[]>emptyList());
+  }
+
+  /**
+   * Returns the AC-3 format given {@code data} containing the EC3SpecificBox according to
+   * ETSI TS 102 366 Annex F.
+   */
+  public static MediaFormat parseAnnexFEAc3Format(ParsableByteArray data) {
+    data.skipBytes(2); // Skip data_rate and num_ind_sub.
+
+    // Read only the first substream.
+    // TODO: Read later substreams?
+    // fscod (sample rate code)
+    int fscod = (data.readUnsignedByte() & 0xC0) >> 6;
+    int sampleRate = SAMPLE_RATES[fscod];
+    int nextByte = data.readUnsignedByte();
+    // Map acmod (audio coding mode) onto a channel count.
+    int channelCount = CHANNEL_COUNTS[(nextByte & 0x0E) >> 1];
+    // lfeon (low frequency effects on)
+    if ((nextByte & 0x01) != 0) {
+      channelCount++;
+    }
+    return MediaFormat.createAudioFormat(MimeTypes.AUDIO_EC3, MediaFormat.NO_VALUE,
+        channelCount, sampleRate, Collections.<byte[]>emptyList());
+  }
+
+  /**
+   * Returns the AC-3 format given {@code data} containing the frame header starting from the sync
+   * word.
+   *
+   * @param data Data to parse, positioned at the start of the syncword.
+   * @return AC-3 format parsed from data in the header.
+   */
+  public static MediaFormat parseFrameAc3Format(ParsableBitArray data) {
+    // Skip syncword and crc1.
+    data.skipBits(4 * 8);
+
+    int fscod = data.readBits(2);
+    int frmsizecod = data.readBits(6);
+    data.skipBits(8); // bsid (5 bits) + bsmod (3 bits)
+    int acmod = data.readBits(3);
+    if ((acmod & 0x01) != 0 && acmod != 1) {
+      data.skipBits(2); // cmixlev
+    }
+    if ((acmod & 0x04) != 0) {
+      data.skipBits(2); // surmixlev
+    }
+    if (acmod == 0x02) {
+      data.skipBits(2); // dsurmod
+    }
+    boolean lfeon = data.readBit();
+    return MediaFormat.createAudioFormat(MimeTypes.AUDIO_AC3, MediaFormat.NO_VALUE,
+        MediaFormat.NO_VALUE, CHANNEL_COUNTS[acmod] + (lfeon ? 1 : 0), SAMPLE_RATES[fscod],
+        BITRATES[frmsizecod / 2] * 1000, Collections.<byte[]>emptyList());
+  }
+
+  /**
+   * Returns the AC-3 frame size in bytes given {@code data} containing the frame header starting
+   * from the sync word.
+   *
+   * @param data Data to parse, positioned at the start of the syncword.
+   * @return The frame size parsed from data in the header.
+   */
+  public static int parseFrameSize(ParsableBitArray data) {
+    // Skip syncword and crc1.
+    data.skipBits(4 * 8);
+
+    int fscod = data.readBits(2);
+    int frmsizecod = data.readBits(6);
+    int sampleRate = SAMPLE_RATES[fscod];
+    int bitrate = BITRATES[frmsizecod / 2];
+    if (sampleRate == 32000) {
+      return 6 * bitrate;
+    } else if (sampleRate == 44100) {
+      return 2 * (FRMSIZECOD_TO_FRAME_SIZE_44_1[frmsizecod / 2] + (frmsizecod % 2));
+    } else { // sampleRate == 48000
+      return 4 * bitrate;
+    }
+  }
+
+  private Ac3Util() {
+    // Prevent instantiation.
+  }
+
+}