diff --git a/include/media/MediaPlayerInterface.h b/include/media/MediaPlayerInterface.h
index f7491d8..8168dff 100644
--- a/include/media/MediaPlayerInterface.h
+++ b/include/media/MediaPlayerInterface.h
@@ -60,6 +60,8 @@
 #define DEFAULT_AUDIOSINK_BUFFERSIZE 1200
 #define DEFAULT_AUDIOSINK_SAMPLERATE 44100
 
+// when the channel mask isn't known, use the channel count to derive a mask in AudioSink::open()
+#define CHANNEL_MASK_USE_CHANNEL_ORDER 0
 
 // callback mechanism for passing messages to MediaPlayer object
 typedef void (*notify_callback_f)(void* cookie,
@@ -91,7 +93,7 @@
         // If no callback is specified, use the "write" API below to submit
         // audio data.
         virtual status_t    open(
-                uint32_t sampleRate, int channelCount,
+                uint32_t sampleRate, int channelCount, audio_channel_mask_t channelMask,
                 audio_format_t format=AUDIO_FORMAT_PCM_16_BIT,
                 int bufferCount=DEFAULT_AUDIOSINK_BUFFERCOUNT,
                 AudioCallback cb = NULL,