diff --git a/include/media/IAudioFlinger.h b/include/media/IAudioFlinger.h
index 7a2ada0..d7471ee 100644
--- a/include/media/IAudioFlinger.h
+++ b/include/media/IAudioFlinger.h
@@ -77,6 +77,8 @@
     virtual     int         channelCount(audio_io_handle_t output) const = 0;
     virtual     audio_format_t format(audio_io_handle_t output) const = 0;
     virtual     size_t      frameCount(audio_io_handle_t output) const = 0;
+
+    // return estimated latency in milliseconds
     virtual     uint32_t    latency(audio_io_handle_t output) const = 0;
 
     /* set/get the audio hardware state. This will probably be used by