--- a/media/libstagefright/binding/Index.cpp
+++ b/media/libstagefright/binding/Index.cpp
@@ -233,30 +233,32 @@ SampleIterator::GetNextKeyframeTime()
   return -1;
 }
 
 Index::Index(const nsTArray<Indice>& aIndex,
              Stream* aSource,
              uint32_t aTrackId,
              bool aIsAudio)
   : mSource(aSource)
+  , mIsAudio(aIsAudio)
 {
   if (aIndex.IsEmpty()) {
     mMoofParser = new MoofParser(aSource, aTrackId, aIsAudio);
   } else {
     if (!mIndex.SetCapacity(aIndex.Length(), fallible)) {
       // OOM.
       return;
     }
     media::IntervalSet<int64_t> intervalTime;
     MediaByteRange intervalRange;
     bool haveSync = false;
     bool progressive = true;
     int64_t lastOffset = 0;
-    for (const Indice& indice : aIndex) {
+    for (size_t i = 0; i < aIndex.Length(); i++) {
+      const Indice& indice = aIndex[i];
       if (indice.sync) {
         haveSync = true;
       }
       if (!haveSync) {
         continue;
       }
 
       Sample sample;
@@ -269,17 +271,18 @@ Index::Index(const nsTArray<Indice>& aIn
       // FIXME: Make this infallible after bug 968520 is done.
       MOZ_ALWAYS_TRUE(mIndex.AppendElement(sample, fallible));
       if (indice.start_offset < lastOffset) {
         NS_WARNING("Chunks in MP4 out of order, expect slow down");
         progressive = false;
       }
       lastOffset = indice.end_offset;
 
-      if (sample.mSync && progressive) {
+      // Pack audio samples in group of 128.
+      if (sample.mSync && progressive && (!mIsAudio || !(i % 128))) {
         if (mDataOffset.Length()) {
           auto& last = mDataOffset.LastElement();
           last.mEndOffset = intervalRange.mEnd;
           NS_ASSERTION(intervalTime.Length() == 1, "Discontinuous samples between keyframes");
           last.mTime.start = intervalTime.GetStart();
           last.mTime.end = intervalTime.GetEnd();
         }
         if (!mDataOffset.AppendElement(MP4DataOffset(mIndex.Length() - 1,
@@ -353,23 +356,35 @@ Index::ConvertByteRangesToTimeRanges(con
     return mLastBufferedRanges;
   }
   mLastCachedRanges = aByteRanges;
 
   if (mDataOffset.Length()) {
     TimeIntervals timeRanges;
     for (const auto& range : aByteRanges) {
       uint32_t start = mDataOffset.IndexOfFirstElementGt(range.mStart - 1);
-      if (start == mDataOffset.Length()) {
+      if (!mIsAudio && start == mDataOffset.Length()) {
         continue;
       }
       uint32_t end = mDataOffset.IndexOfFirstElementGt(range.mEnd, MP4DataOffset::EndOffsetComparator());
-      if (end < start) {
+      if (!mIsAudio && end < start) {
         continue;
       }
+      if (mIsAudio && start &&
+          range.Intersects(MediaByteRange(mDataOffset[start-1].mStartOffset,
+                                          mDataOffset[start-1].mEndOffset))) {
+        // Check if previous audio data block contains some available samples.
+        for (size_t i = mDataOffset[start-1].mIndex; i < mIndex.Length(); i++) {
+          if (range.ContainsStrict(mIndex[i].mByteRange)) {
+            timeRanges +=
+              TimeInterval(TimeUnit::FromMicroseconds(mIndex[i].mCompositionRange.start),
+                           TimeUnit::FromMicroseconds(mIndex[i].mCompositionRange.end));
+          }
+        }
+      }
       if (end > start) {
         timeRanges +=
           TimeInterval(TimeUnit::FromMicroseconds(mDataOffset[start].mTime.start),
                        TimeUnit::FromMicroseconds(mDataOffset[end-1].mTime.end));
       }
       if (end < mDataOffset.Length()) {
         // Find samples in partial block contained in the byte range.
         for (size_t i = mDataOffset[end].mIndex;

--- a/media/libstagefright/binding/include/mp4_demuxer/Index.h
+++ b/media/libstagefright/binding/include/mp4_demuxer/Index.h
@@ -110,12 +110,13 @@ private:
   Stream* mSource;
   FallibleTArray<Sample> mIndex;
   FallibleTArray<MP4DataOffset> mDataOffset;
   nsAutoPtr<MoofParser> mMoofParser;
 
   // ConvertByteRangesToTimeRanges cache
   mozilla::MediaByteRangeSet mLastCachedRanges;
   mozilla::media::TimeIntervals mLastBufferedRanges;
+  bool mIsAudio;
 };
 }
 
 #endif