Parse AAC initialisation data in MatroskaExtractor

This aligns mkv with mp4, flv and ts extractors.

This issue was found when AAC in an MKV container was not offloaded
as format.codecs was null.

PiperOrigin-RevId: 310170759

library/extractor/src/main/java/com/google/android/exoplayer2/extractor/mkv/MatroskaExtractor.java

@@ -23,6 +23,7 @@ import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.ParserException;
+import com.google.android.exoplayer2.audio.AacUtil;
 import com.google.android.exoplayer2.audio.Ac3Util;
 import com.google.android.exoplayer2.audio.MpegAudioUtil;
 import com.google.android.exoplayer2.drm.DrmInitData;
@@ -1940,6 +1941,7 @@ public class MatroskaExtractor implements Extractor {
       int maxInputSize = Format.NO_VALUE;
       @C.PcmEncoding int pcmEncoding = Format.NO_VALUE;
       @Nullable List<byte[]> initializationData = null;
+      @Nullable String codecs = null;
       switch (codecId) {
         case CODEC_ID_VP8:
           mimeType = MimeTypes.VIDEO_VP8;
@@ -2001,6 +2003,12 @@ public class MatroskaExtractor implements Extractor {
         case CODEC_ID_AAC:
           mimeType = MimeTypes.AUDIO_AAC;
           initializationData = Collections.singletonList(codecPrivate);
+          AacUtil.Config aacConfig = AacUtil.parseAudioSpecificConfig(codecPrivate);
+          // Update sampleRate and channelCount from the AudioSpecificConfig initialization data,
+          // which is more reliable. See [Internal: b/10903778].
+          sampleRate = aacConfig.sampleRateHz;
+          channelCount = aacConfig.channelCount;
+          codecs = aacConfig.codecs;
           break;
         case CODEC_ID_MP2:
           mimeType = MimeTypes.AUDIO_MPEG_L2;
@@ -2163,6 +2171,7 @@ public class MatroskaExtractor implements Extractor {
               .setLanguage(language)
               .setSelectionFlags(selectionFlags)
               .setInitializationData(initializationData)
+              .setCodecs(codecs)
               .setDrmInitData(drmInitData)
               .build();