Add ENCODING_ constants for AAC

PiperOrigin-RevId: 297579793

library/common/src/main/java/com/google/android/exoplayer2/C.java

@@ -160,6 +160,11 @@ public final class C {
     ENCODING_PCM_32BIT,
     ENCODING_PCM_FLOAT,
     ENCODING_MP3,
+    ENCODING_AAC_LC,
+    ENCODING_AAC_HE_V1,
+    ENCODING_AAC_HE_V2,
+    ENCODING_AAC_XHE,
+    ENCODING_AAC_ELD,
     ENCODING_AC3,
     ENCODING_E_AC3,
     ENCODING_E_AC3_JOC,
@@ -205,6 +210,16 @@ public final class C {
   public static final int ENCODING_PCM_FLOAT = AudioFormat.ENCODING_PCM_FLOAT;
   /** @see AudioFormat#ENCODING_MP3 */
   public static final int ENCODING_MP3 = AudioFormat.ENCODING_MP3;
+  /** @see AudioFormat#ENCODING_AAC_LC */
+  public static final int ENCODING_AAC_LC = AudioFormat.ENCODING_AAC_LC;
+  /** @see AudioFormat#ENCODING_AAC_HE_V1 */
+  public static final int ENCODING_AAC_HE_V1 = AudioFormat.ENCODING_AAC_HE_V1;
+  /** @see AudioFormat#ENCODING_AAC_HE_V2 */
+  public static final int ENCODING_AAC_HE_V2 = AudioFormat.ENCODING_AAC_HE_V2;
+  /** @see AudioFormat#ENCODING_AAC_XHE */
+  public static final int ENCODING_AAC_XHE = AudioFormat.ENCODING_AAC_XHE;
+  /** @see AudioFormat#ENCODING_AAC_ELD */
+  public static final int ENCODING_AAC_ELD = AudioFormat.ENCODING_AAC_ELD;
   /** @see AudioFormat#ENCODING_AC3 */
   public static final int ENCODING_AC3 = AudioFormat.ENCODING_AC3;
   /** @see AudioFormat#ENCODING_E_AC3 */

library/common/src/main/java/com/google/android/exoplayer2/util/CodecSpecificDataUtil.java

@@ -26,6 +26,8 @@ import java.util.List;
 /** Provides utilities for handling various types of codec-specific data. */
 public final class CodecSpecificDataUtil {
 
+  private static final String TAG = "CodecSpecificDataUtil";
+
   /** Holds sample format information for AAC audio. */
   public static final class AacConfig {
 
@@ -43,6 +45,24 @@ public final class CodecSpecificDataUtil {
     }
   }
 
+  // AAC audio sample count constants assume the frameLengthFlag in the access unit is 0.
+  /**
+   * Number of raw audio samples that are produced per channel when decoding an AAC LC access unit.
+   */
+  public static final int AAC_LC_AUDIO_SAMPLE_COUNT = 1024;
+  /**
+   * Number of raw audio samples that are produced per channel when decoding an AAC XHE access unit.
+   */
+  public static final int AAC_XHE_AUDIO_SAMPLE_COUNT = AAC_LC_AUDIO_SAMPLE_COUNT;
+  /**
+   * Number of raw audio samples that are produced per channel when decoding an AAC HE access unit.
+   */
+  public static final int AAC_HE_AUDIO_SAMPLE_COUNT = 2048;
+  /**
+   * Number of raw audio samples that are produced per channel when decoding an AAC LD access unit.
+   */
+  public static final int AAC_LD_AUDIO_SAMPLE_COUNT = 512;
+
   private static final byte[] NAL_START_CODE = new byte[] {0, 0, 0, 1};
 
   private static final int AUDIO_SPECIFIC_CONFIG_FREQUENCY_INDEX_ARBITRARY = 0xF;
@@ -97,10 +117,14 @@ public final class CodecSpecificDataUtil {
   private static final int AUDIO_OBJECT_TYPE_AAC_SBR = 5;
   // Error Resilient Bit-Sliced Arithmetic Coding.
   private static final int AUDIO_OBJECT_TYPE_AAC_ER_BSAC = 22;
+  // Enhanced low delay.
+  private static final int AUDIO_OBJECT_TYPE_AAC_ELD = 23;
   // Parametric Stereo.
   private static final int AUDIO_OBJECT_TYPE_AAC_PS = 29;
   // Escape code for extended audio object types.
   private static final int AUDIO_OBJECT_TYPE_ESCAPE = 31;
+  // Extended high efficiency.
+  private static final int AUDIO_OBJECT_TYPE_AAC_XHE = 42;
 
   private CodecSpecificDataUtil() {}
 
@@ -230,6 +254,25 @@ public final class CodecSpecificDataUtil {
     return specificConfig;
   }
 
+  /** Returns the encoding for a given AAC audio object type. */
+  @C.Encoding
+  public static int getEncodingForAacAudioObjectType(int audioObjectType) {
+    switch (audioObjectType) {
+      case AUDIO_OBJECT_TYPE_AAC_LC:
+        return C.ENCODING_AAC_LC;
+      case AUDIO_OBJECT_TYPE_AAC_SBR:
+        return C.ENCODING_AAC_HE_V1;
+      case AUDIO_OBJECT_TYPE_AAC_PS:
+        return C.ENCODING_AAC_HE_V2;
+      case AUDIO_OBJECT_TYPE_AAC_XHE:
+        return C.ENCODING_AAC_XHE;
+      case AUDIO_OBJECT_TYPE_AAC_ELD:
+        return C.ENCODING_AAC_ELD;
+      default:
+        return C.ENCODING_INVALID;
+    }
+  }
+
   /**
    * Parses an ALAC AudioSpecificConfig (i.e. an <a
    * href="https://github.com/macosforge/alac/blob/master/ALACMagicCookieDescription.txt">ALACSpecificConfig</a>).
@@ -406,7 +449,10 @@ public final class CodecSpecificDataUtil {
 
   private static void parseGaSpecificConfig(ParsableBitArray bitArray, int audioObjectType,
       int channelConfiguration) {
-    bitArray.skipBits(1); // frameLengthFlag.
+    boolean frameLengthFlag = bitArray.readBit();
+    if (frameLengthFlag) {
+      Log.w(TAG, "Unexpected AAC frameLengthFlag = 1");
+    }
     boolean dependsOnCoreDecoder = bitArray.readBit();
     if (dependsOnCoreDecoder) {
       bitArray.skipBits(14); // coreCoderDelay.

library/core/src/main/java/com/google/android/exoplayer2/audio/DefaultAudioSink.java

@@ -28,6 +28,7 @@ import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.PlaybackParameters;
 import com.google.android.exoplayer2.audio.AudioProcessor.UnhandledAudioFormatException;
 import com.google.android.exoplayer2.util.Assertions;
+import com.google.android.exoplayer2.util.CodecSpecificDataUtil;
 import com.google.android.exoplayer2.util.Log;
 import com.google.android.exoplayer2.util.Util;
 import java.nio.ByteBuffer;
@@ -1217,6 +1218,21 @@ public final class DefaultAudioSink implements AudioSink {
       case C.ENCODING_MP3:
         // Maximum bitrate for MPEG-1 layer III: 320 kbit/s.
         return 320 * 1000 / 8;
+      case C.ENCODING_AAC_LC:
+        // Maximum bitrates for AAC profiles from the Fraunhofer FDK AAC encoder documentation:
+        // https://cs.android.com/android/platform/superproject/+/android-9.0.0_r8:external/aac/libAACenc/include/aacenc_lib.h;l=718
+        return 800 * 1000 / 8;
+      case C.ENCODING_AAC_HE_V1:
+        return 128 * 1000 / 8;
+      case C.ENCODING_AAC_HE_V2:
+        return 56 * 1000 / 8;
+      case C.ENCODING_AAC_XHE:
+        // Fraunhofer documentation says "500 kbit/s and above" for stereo, so we use a rate
+        // generously above the 500 kbit/s level.
+        return 2048 * 1000 / 8;
+      case C.ENCODING_AAC_ELD:
+        // Fraunhofer documentation shows AAC-ELD as useful for up to ~ 64 kbit/s.
+        return 64 * 1000 / 8;
       case C.ENCODING_AC3:
         return 640 * 1000 / 8;
       case C.ENCODING_E_AC3:
@@ -1248,6 +1264,15 @@ public final class DefaultAudioSink implements AudioSink {
     switch (encoding) {
       case C.ENCODING_MP3:
         return MpegAudioUtil.parseMpegAudioFrameSampleCount(buffer.get(buffer.position()));
+      case C.ENCODING_AAC_LC:
+        return CodecSpecificDataUtil.AAC_LC_AUDIO_SAMPLE_COUNT;
+      case C.ENCODING_AAC_HE_V1:
+      case C.ENCODING_AAC_HE_V2:
+        return CodecSpecificDataUtil.AAC_HE_AUDIO_SAMPLE_COUNT;
+      case C.ENCODING_AAC_XHE:
+        return CodecSpecificDataUtil.AAC_XHE_AUDIO_SAMPLE_COUNT;
+      case C.ENCODING_AAC_ELD:
+        return CodecSpecificDataUtil.AAC_LD_AUDIO_SAMPLE_COUNT;
       case C.ENCODING_DTS:
       case C.ENCODING_DTS_HD:
         return DtsUtil.parseDtsAudioSampleCount(buffer);