diff --git a/include/media/IMediaSource.h b/include/media/IMediaSource.h
index 1420120..f7586a7 100644
--- a/include/media/IMediaSource.h
+++ b/include/media/IMediaSource.h
@@ -26,6 +26,7 @@
 struct MediaSource;
 class MetaData;
 class MediaBuffer;
+class MediaBufferGroup;
 
 class IMediaSource : public IInterface {
 public:
@@ -112,6 +113,8 @@
 class BnMediaSource: public BnInterface<IMediaSource>
 {
 public:
+    BnMediaSource();
+
     virtual status_t    onTransact(uint32_t code, const Parcel& data, Parcel* reply,
                                 uint32_t flags = 0);
 
@@ -122,6 +125,12 @@
     virtual status_t setBuffers(const Vector<MediaBuffer *> & /* buffers */) {
         return ERROR_UNSUPPORTED;
     }
+
+protected:
+    virtual ~BnMediaSource();
+
+private:
+    MediaBufferGroup *mGroup;
 };
 
 
diff --git a/include/media/stagefright/MediaBuffer.h b/include/media/stagefright/MediaBuffer.h
index 1e0c7d4..18b80e3 100644
--- a/include/media/stagefright/MediaBuffer.h
+++ b/include/media/stagefright/MediaBuffer.h
@@ -48,6 +48,9 @@
 
 class MediaBuffer : public MediaBufferBase {
 public:
+    // allocations larger than or equal to this will use shared memory.
+    static const size_t kSharedMemThreshold = 64 * 1024;
+
     // The underlying data remains the responsibility of the caller!
     MediaBuffer(void *data, size_t size);
 
diff --git a/include/media/stagefright/MediaBufferGroup.h b/include/media/stagefright/MediaBufferGroup.h
index a006f7f..7ca3fa1 100644
--- a/include/media/stagefright/MediaBufferGroup.h
+++ b/include/media/stagefright/MediaBufferGroup.h
@@ -39,7 +39,11 @@
     // The returned buffer will have a reference count of 1.
     // If nonBlocking is true and a buffer is not immediately available,
     // buffer is set to NULL and it returns WOULD_BLOCK.
-    status_t acquire_buffer(MediaBuffer **buffer, bool nonBlocking = false);
+    // If requestedSize is 0, any free MediaBuffer will be returned.
+    // If requestedSize is > 0, the returned MediaBuffer should have buffer
+    // size of at least requstedSize.
+    status_t acquire_buffer(
+            MediaBuffer **buffer, bool nonBlocking = false, size_t requestedSize = 0);
 
 protected:
     virtual void signalBufferReturned(MediaBuffer *buffer);