diff --git a/services/audioflinger/AudioFlinger.h b/services/audioflinger/AudioFlinger.h
index 2e259c0..d9f2972 100644
--- a/services/audioflinger/AudioFlinger.h
+++ b/services/audioflinger/AudioFlinger.h
@@ -58,6 +58,15 @@
 
 // ----------------------------------------------------------------------------
 
+// AudioFlinger has a hard-coded upper limit of 2 channels for capture and playback.
+// There is support for > 2 channel tracks down-mixed to 2 channel output via a down-mix effect.
+// Adding full support for > 2 channel capture or playback would require more than simply changing
+// this #define.  There is an independent hard-coded upper limit in AudioMixer;
+// removing that AudioMixer limit would be necessary but insufficient to support > 2 channels.
+// The macro FCC_2 highlights some (but not all) places where there is are 2-channel assumptions.
+// Search also for "2", "left", "right", "[0]", "[1]", ">> 16", "<< 16", etc.
+#define FCC_2 2     // FCC_2 = Fixed Channel Count 2
+
 static const nsecs_t kDefaultStandbyTimeInNsecs = seconds(3);
 
 class AudioFlinger :