Surface the noise estimate of the NS to be used by other components

webrtc/modules/audio_processing/ns/noise_suppression.h

Index: webrtc/modules/audio_processing/ns/noise_suppression.h
diff --git a/webrtc/modules/audio_processing/ns/noise_suppression.h b/webrtc/modules/audio_processing/ns/noise_suppression.h
index 8018118b60065f3cb422907f1011f5504b641cc9..61fb18a832ba16b92be1cbaca4841e942e9928fd 100644
--- a/webrtc/modules/audio_processing/ns/noise_suppression.h
+++ b/webrtc/modules/audio_processing/ns/noise_suppression.h
@@ -109,6 +109,24 @@ void WebRtcNs_Process(NsHandle* NS_inst,
  */
 float WebRtcNs_prior_speech_probability(NsHandle* handle);
 
+/* Returns a pointer to the noise estimate per frequency bin. The number of
+ * frequency bins can be get using WebRtcNs_num_freq().
+ *
+ * Input
+ *      - handle        : Noise suppression instance.
+ *
+ * Return value         : Pointer to the noise estimate per frequency bin.
+ *                        NULL pointer - NULL pointer or uninitialized instance.
+ */
+float* WebRtcNs_noise_estimate(NsHandle* handle);

[turaj, 2016/02/05 01:47:58]

shouldn't be const float*?

[aluebs-webrtc, 2016/02/06 00:12:28]

Nice catch! Done.

+
+/* Returns the number of frequency bins, which is the length of the noise
+ * estimate for example.
+ *
+ * Return value         : Number of frequency bins.
+ */
+size_t WebRtcNs_num_freq();

[turaj, 2016/02/05 01:47:58]

Just a suggestion: these two can be combined 

float* WebRtcNs_noise_estimate(NsHandle* handle, size_t* num_freq) where
num_freq == 0 means uninitialized. Doesn't need to return nullptr

[aluebs-webrtc, 2016/02/06 00:12:28]

I think I prefer to keep them separate, since the num_freq is a constant that
that doesn't depend on the handle and this makes it simple to just re-size the
container once and then average the noise estimation for each channel in
noise_suppression_impl.cc. But if you have a strong opinion, I am happy to
combine them.

+
 #ifdef __cplusplus
 }
 #endif