1 files changed, 23 insertions, 1 deletions
diff --git a/media/libstagefright/matroska/MatroskaExtractor.cpp b/media/libstagefright/matroska/MatroskaExtractor.cpp
index ecc2573..e6ed900 100644
--- a/media/libstagefright/matroska/MatroskaExtractor.cpp
+++ b/media/libstagefright/matroska/MatroskaExtractor.cpp
@@ -521,8 +521,9 @@ status_t MatroskaSource::readBlock() {
     const mkvparser::Block *block = mBlockIter.block();
 
     int64_t timeUs = mBlockIter.blockTimeUs();
+    int frameCount = block->GetFrameCount();
 
-    for (int i = 0; i < block->GetFrameCount(); ++i) {
+    for (int i = 0; i < frameCount; ++i) {
         const mkvparser::Block::Frame &frame = block->GetFrame(i);
 
         MediaBuffer *mbuf = new MediaBuffer(frame.len);
@@ -542,6 +543,27 @@ status_t MatroskaSource::readBlock() {
 
     mBlockIter.advance();
 
+    if (!mBlockIter.eos() && frameCount > 1) {
+        // For files with lacing enabled, we need to amend they kKeyTime of
+        // each frame so that their kKeyTime are advanced accordingly (instead
+        // of being set to the same value). To do this, we need to find out
+        // the duration of the block using the start time of the next block.
+        int64_t duration = mBlockIter.blockTimeUs() - timeUs;
+        int64_t durationPerFrame = duration / frameCount;
+        int64_t durationRemainder = duration % frameCount;
+
+        // We split duration to each of the frame, distributing the remainder (if any)
+        // to the later frames. The later frames are processed first due to the
+        // use of the iterator for the doubly linked list
+        List<MediaBuffer *>::iterator it = mPendingFrames.end();
+        for (int i = frameCount - 1; i >= 0; --i) {
+            --it;
+            int64_t frameRemainder = durationRemainder >= frameCount - i ? 1 : 0;
+            int64_t frameTimeUs = timeUs + durationPerFrame * i + frameRemainder;
+            (*it)->meta_data()->setInt64(kKeyTime, frameTimeUs);
+        }
+    }
+
     return OK;
 }