diff --git a/include/media/AudioIoDescriptor.h b/include/media/AudioIoDescriptor.h
index a4907cc..fed86c9 100644
--- a/include/media/AudioIoDescriptor.h
+++ b/include/media/AudioIoDescriptor.h
@@ -35,7 +35,7 @@
     AudioIoDescriptor() :
         mIoHandle(AUDIO_IO_HANDLE_NONE),
         mSamplingRate(0), mFormat(AUDIO_FORMAT_DEFAULT), mChannelMask(AUDIO_CHANNEL_NONE),
-        mFrameCount(0), mLatency(0)
+        mFrameCount(0), mFrameCountHAL(0), mLatency(0)
     {
         memset(&mPatch, 0, sizeof(struct audio_patch));
     }
@@ -62,6 +62,7 @@
     audio_format_t          mFormat;
     audio_channel_mask_t    mChannelMask;
     size_t                  mFrameCount;
+    size_t                  mFrameCountHAL;
     uint32_t                mLatency;   // only valid for output
 };
 
diff --git a/include/media/AudioSystem.h b/include/media/AudioSystem.h
index c9eac2e..585ef59 100644
--- a/include/media/AudioSystem.h
+++ b/include/media/AudioSystem.h
@@ -43,6 +43,8 @@
 {
 public:
 
+    // FIXME Declare in binder opcode order, similarly to IAudioFlinger.h and IAudioFlinger.cpp
+
     /* These are static methods to control the system-wide AudioFlinger
      * only privileged processes can have access to them
      */
@@ -117,8 +119,8 @@
     // returns the audio HAL sample rate
     static status_t getSamplingRate(audio_io_handle_t ioHandle,
                                           uint32_t* samplingRate);
-    // returns the number of frames per audio HAL buffer. Corresponds to
-    // audio_stream->get_buffer_size()/audio_stream_out/in_frame_size()
+    // For output threads with a fast mixer, returns the number of frames per normal mixer buffer.
+    // For output threads without a fast mixer, or for input, this is same as getFrameCountHAL().
     static status_t getFrameCount(audio_io_handle_t ioHandle,
                                   size_t* frameCount);
     // returns the audio output latency in ms. Corresponds to
@@ -166,6 +168,12 @@
     // Indicate JAVA services are ready (scheduling, power management ...)
     static status_t systemReady();
 
+    // Returns the number of frames per audio HAL buffer.
+    // Corresponds to audio_stream->get_buffer_size()/audio_stream_in_frame_size() for input.
+    // See also getFrameCount().
+    static status_t getFrameCountHAL(audio_io_handle_t ioHandle,
+                                     size_t* frameCount);
+
     // Events used to synchronize actions between audio sessions.
     // For instance SYNC_EVENT_PRESENTATION_COMPLETE can be used to delay recording start until
     // playback is complete on another audio session.
diff --git a/include/media/IAudioFlinger.h b/include/media/IAudioFlinger.h
index e48aa1c..1ade4ba 100644
--- a/include/media/IAudioFlinger.h
+++ b/include/media/IAudioFlinger.h
@@ -103,6 +103,9 @@
      * and therefore can be cached.
      */
     virtual     uint32_t    sampleRate(audio_io_handle_t ioHandle) const = 0;
+
+    // reserved; formerly channelCount()
+
     virtual     audio_format_t format(audio_io_handle_t output) const = 0;
     virtual     size_t      frameCount(audio_io_handle_t ioHandle) const = 0;
 
@@ -247,6 +250,9 @@
 
     /* Indicate JAVA services are ready (scheduling, power management ...) */
     virtual status_t systemReady() = 0;
+
+    // Returns the number of frames per audio HAL buffer.
+    virtual size_t frameCountHAL(audio_io_handle_t ioHandle) const = 0;
 };