Merge pull request #6379 from wingyippp:flac-seek-map-two-points

PiperOrigin-RevId: 272856747

extensions/flac/src/main/java/com/google/android/exoplayer2/ext/flac/FlacDecoderJni.java

@@ -19,6 +19,8 @@ import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.ParserException;
 import com.google.android.exoplayer2.extractor.ExtractorInput;
+import com.google.android.exoplayer2.extractor.SeekMap;
+import com.google.android.exoplayer2.extractor.SeekPoint;
 import com.google.android.exoplayer2.util.FlacStreamMetadata;
 import com.google.android.exoplayer2.util.Util;
 import java.io.IOException;
@@ -216,15 +218,25 @@ import java.nio.ByteBuffer;
   }
 
   /**
-   * Maps a seek position in microseconds to a corresponding position (byte offset) in the flac
+   * Maps a seek position in microseconds to the corresponding {@link SeekMap.SeekPoints} in the
    * stream.
    *
    * @param timeUs A seek position in microseconds.
-   * @return The corresponding position (byte offset) in the flac stream or -1 if the stream doesn't
-   * have a seek table.
+   * @return The corresponding {@link SeekMap.SeekPoints} obtained from the seek table, or {@code
+   *     null} if the stream doesn't have a seek table.
    */
-  public long getSeekPosition(long timeUs) {
-    return flacGetSeekPosition(nativeDecoderContext, timeUs);
+  @Nullable
+  public SeekMap.SeekPoints getSeekPoints(long timeUs) {
+    long[] seekPoints = new long[4];
+    if (!flacGetSeekPoints(nativeDecoderContext, timeUs, seekPoints)) {
+      return null;
+    }
+    SeekPoint firstSeekPoint = new SeekPoint(seekPoints[0], seekPoints[1]);
+    SeekPoint secondSeekPoint =
+        seekPoints[2] == seekPoints[0]
+            ? firstSeekPoint
+            : new SeekPoint(seekPoints[2], seekPoints[3]);
+    return new SeekMap.SeekPoints(firstSeekPoint, secondSeekPoint);
   }
 
   public String getStateString() {
@@ -283,7 +295,7 @@ import java.nio.ByteBuffer;
 
   private native long flacGetNextFrameFirstSampleIndex(long context);
 
-  private native long flacGetSeekPosition(long context, long timeUs);
+  private native boolean flacGetSeekPoints(long context, long timeUs, long[] outSeekPoints);
 
   private native String flacGetStateString(long context);
 

extensions/flac/src/main/java/com/google/android/exoplayer2/ext/flac/FlacExtractor.java

@@ -276,10 +276,10 @@ public final class FlacExtractor implements Extractor {
       FlacStreamMetadata streamMetadata,
       long streamLength,
       ExtractorOutput output) {
-    boolean hasSeekTable = decoderJni.getSeekPosition(/* timeUs= */ 0) != -1;
+    boolean haveSeekTable = decoderJni.getSeekPoints(/* timeUs= */ 0) != null;
     FlacBinarySearchSeeker binarySearchSeeker = null;
     SeekMap seekMap;
-    if (hasSeekTable) {
+    if (haveSeekTable) {
       seekMap = new FlacSeekMap(streamMetadata.durationUs(), decoderJni);
     } else if (streamLength != C.LENGTH_UNSET) {
       long firstFramePosition = decoderJni.getDecodePosition();
@@ -341,8 +341,8 @@ public final class FlacExtractor implements Extractor {
 
     @Override
     public SeekPoints getSeekPoints(long timeUs) {
-      // TODO: Access the seek table via JNI to return two seek points when appropriate.
-      return new SeekPoints(new SeekPoint(timeUs, decoderJni.getSeekPosition(timeUs)));
+      @Nullable SeekPoints seekPoints = decoderJni.getSeekPoints(timeUs);
+      return seekPoints == null ? new SeekPoints(SeekPoint.START) : seekPoints;
     }
 
     @Override

extensions/flac/src/main/jni/flac_jni.cc

@@ -17,6 +17,7 @@
 #include <android/log.h>
 #include <jni.h>
 
+#include <array>
 #include <cstdlib>
 #include <cstring>
 
@@ -198,9 +199,15 @@ DECODER_FUNC(jlong, flacGetNextFrameFirstSampleIndex, jlong jContext) {
   return context->parser->getNextFrameFirstSampleIndex();
 }
 
-DECODER_FUNC(jlong, flacGetSeekPosition, jlong jContext, jlong timeUs) {
+DECODER_FUNC(jboolean, flacGetSeekPoints, jlong jContext, jlong timeUs,
+             jlongArray outSeekPoints) {
   Context *context = reinterpret_cast<Context *>(jContext);
-  return context->parser->getSeekPosition(timeUs);
+  std::array<int64_t, 4> result;
+  bool success = context->parser->getSeekPositions(timeUs, result);
+  if (success) {
+    env->SetLongArrayRegion(outSeekPoints, 0, result.size(), result.data());
+  }
+  return success;
 }
 
 DECODER_FUNC(jstring, flacGetStateString, jlong jContext) {

extensions/flac/src/main/jni/flac_parser.cc

@@ -438,22 +438,41 @@ size_t FLACParser::readBuffer(void *output, size_t output_size) {
   return bufferSize;
 }
 
-int64_t FLACParser::getSeekPosition(int64_t timeUs) {
+bool FLACParser::getSeekPositions(int64_t timeUs,
+                                  std::array<int64_t, 4> &result) {
   if (!mSeekTable) {
-    return -1;
+    return false;
   }
 
-  int64_t sample = (timeUs * getSampleRate()) / 1000000LL;
-  if (sample >= getTotalSamples()) {
-      sample = getTotalSamples();
+  unsigned sampleRate = getSampleRate();
+  int64_t totalSamples = getTotalSamples();
+  int64_t targetSampleNumber = (timeUs * sampleRate) / 1000000LL;
+  if (targetSampleNumber >= totalSamples) {
+    targetSampleNumber = totalSamples - 1;
   }
 
   FLAC__StreamMetadata_SeekPoint* points = mSeekTable->points;
-  for (unsigned i = mSeekTable->num_points; i > 0; ) {
-    i--;
-    if (points[i].sample_number <= sample) {
-      return firstFrameOffset + points[i].stream_offset;
+  unsigned length = mSeekTable->num_points;
+
+  for (unsigned i = length; i != 0; i--) {
+    int64_t sampleNumber = points[i - 1].sample_number;
+    if (sampleNumber <= targetSampleNumber) {
+      result[0] = (sampleNumber * 1000000LL) / sampleRate;
+      result[1] = firstFrameOffset + points[i - 1].stream_offset;
+      if (sampleNumber == targetSampleNumber || i >= length) {
+        // exact seek, or no following seek point.
+        result[2] = result[0];
+        result[3] = result[1];
+      } else {
+        result[2] = (points[i].sample_number * 1000000LL) / sampleRate;
+        result[3] = firstFrameOffset + points[i].stream_offset;
+      }
+      return true;
     }
   }
-  return firstFrameOffset;
+  result[0] = 0;
+  result[1] = firstFrameOffset;
+  result[2] = 0;
+  result[3] = firstFrameOffset;
+  return true;
 }

extensions/flac/src/main/jni/include/flac_parser.h

@@ -19,6 +19,7 @@
 
 #include <stdint.h>
 
+#include <array>
 #include <cstdlib>
 #include <string>
 #include <vector>
@@ -84,7 +85,7 @@ class FLACParser {
   bool decodeMetadata();
   size_t readBuffer(void *output, size_t output_size);
 
-  int64_t getSeekPosition(int64_t timeUs);
+  bool getSeekPositions(int64_t timeUs, std::array<int64_t, 4> &result);
 
   void flush() {
     reset(mCurrentPos);