diff --git a/services/audioflinger/AudioResampler.h b/services/audioflinger/AudioResampler.h
index 29dc5b6..33e64ce 100644
--- a/services/audioflinger/AudioResampler.h
+++ b/services/audioflinger/AudioResampler.h
@@ -56,6 +56,14 @@
     // set the PTS of the next buffer output by the resampler
     virtual void setPTS(int64_t pts);
 
+    // Resample int16_t samples from provider and accumulate into 'out'.
+    // A mono provider delivers a sequence of samples.
+    // A stereo provider delivers a sequence of interleaved pairs of samples.
+    // Multi-channel providers are not supported.
+    // In either case, 'out' holds interleaved pairs of fixed-point signed Q19.12.
+    // That is, for a mono provider, there is an implicit up-channeling.
+    // Since this method accumulates, the caller is responsible for clearing 'out' initially.
+    // FIXME assumes provider is always successful; it should return the actual frame count.
     virtual void resample(int32_t* out, size_t outFrameCount,
             AudioBufferProvider* provider) = 0;