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Add detection for DTS-HD audio tracks in MatroskaExtractor #2485

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Add detection for DTS-HD audio tracks in MatroskaExtractor #2485

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52 changes: 51 additions & 1 deletion libraries/extractor/src/main/java/androidx/media3/extractor/mkv/MatroskaExtractor.java
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Original file line number Diff line number Diff line change
Expand Up @@ -46,6 +46,7 @@
import androidx.media3.extractor.AacUtil;
import androidx.media3.extractor.AvcConfig;
import androidx.media3.extractor.ChunkIndex;
import androidx.media3.extractor.DtsUtil;
import androidx.media3.extractor.Extractor;
import androidx.media3.extractor.ExtractorInput;
import androidx.media3.extractor.ExtractorOutput;
Expand Down Expand Up @@ -1564,6 +1565,53 @@ private int writeSampleData(ExtractorInput input, Track track, int size, boolean
return finishWriteSampleData();
}

if (CODEC_ID_DTS.equals(track.codecId) && !track.dtsAnalyzed) {
long remaining = input.getLength() - input.getPosition();
// Limit the peek ahead to be up to the max frame size (16383) plus the
// sync word of the second frame
int scanLength = (int)Math.min(16383 + 95, remaining);
byte[] buf = new byte[scanLength];
track.dtsAnalyzed = true;

input.advancePeekPosition(0);
input.peekFully(buf, 0, buf.length);
input.resetPeekPosition();

final ByteBuffer bb = ByteBuffer.wrap(buf);
for (int idx = 0; idx + 4 <= buf.length; idx += 4) {
int word = bb.getInt(idx);

if (DtsUtil.getFrameType(word) == DtsUtil.FRAME_TYPE_CORE) {
// header starts immediately after the 4‐byte sync
int headerStart = idx + 4;
if (headerStart + 10 > buf.length) {
break;
}

bb.mark();
bb.position(headerStart);
byte[] header = new byte[10];
bb.get(header);
bb.reset();
int fsize = DtsUtil.getDtsFrameSize(header);
if (fsize <= 0 || idx + fsize + 4 > buf.length) {
break;
}

word = bb.getInt(idx + fsize);

if (DtsUtil.getFrameType(word) == DtsUtil.FRAME_TYPE_EXTENSION_SUBSTREAM) {
track.formatBuilder.setSampleMimeType(MimeTypes.AUDIO_DTS_HD);
track.output.format(track.formatBuilder.build());
}

// After finding a valid DTS core frame we can break the loop, there is no
// need to evaluate the rest of the buffer.
break;
}
}
}

TrackOutput output = track.output;
if (!sampleEncodingHandled) {
if (track.hasContentEncryption) {
Expand Down Expand Up @@ -2135,6 +2183,7 @@ protected static final class Track {
public long codecDelayNs = 0;
public long seekPreRollNs = 0;
public @MonotonicNonNull TrueHdSampleRechunker trueHdSampleRechunker;
public boolean dtsAnalyzed = false;

// Text elements.
public boolean flagForced;
Expand All @@ -2143,6 +2192,7 @@ protected static final class Track {

// Set when the output is initialized. nalUnitLengthFieldLength is only set for H264/H265.
public @MonotonicNonNull TrackOutput output;
public Format.Builder formatBuilder;
public int nalUnitLengthFieldLength;

/** Initializes the track with an output. */
Expand Down Expand Up @@ -2369,7 +2419,7 @@ public void initializeOutput(ExtractorOutput output, int trackId) throws ParserE
selectionFlags |= flagForced ? C.SELECTION_FLAG_FORCED : 0;

int type;
Format.Builder formatBuilder = new Format.Builder();
formatBuilder = new Format.Builder();
// TODO: Consider reading the name elements of the tracks and, if present, incorporating them
// into the trackId passed when creating the formats.
if (MimeTypes.isAudio(mimeType)) {
Expand Down