RNN VAD weights: output layer sizes and scaling factor

Minor changes required to land
https://webrtc-review.googlesource.com/c/src/+/72060/

Bug: webrtc:9076
Change-Id: I767a1b3f735428e7db8a0cbf53f70af4148f27bb
Reviewed-on: https://chromium-review.googlesource.com/1030273Reviewed-by: Patrik Höglund <phoglund@chromium.org>
Commit-Queue: Ale Bzk <alessiob@chromium.org>
Cr-Commit-Position: refs/heads/master@{#554361}

third_party/rnnoise/README.chromium

@@ -22,3 +22,4 @@ Local Modifications:
 * KissFFT: non-floating point parts removed, code clean, from C to C++,
   class wrapper added
 * BUILD targets and KissFFT unit tests added
+* rnn_vad_weights.h: output layer sizes + weights scaling factor

third_party/rnnoise/src/rnn_vad_weights.cc

@@ -392,10 +392,10 @@ const int8_t kHiddenGruBias[72] = {
     62,  6,   -2,  0,    0,   100, -16,  26,  -24, 56,  26, -10,
     -33, 41,  70,  109,  -29, 127, 34,   -66, 49,  53,  27, 62};
 
-const int8_t kOutputWeights[24] = {127,  127, 127,  127,  127,  20,   127, -126,
-                                   -126, -54, 14,   125,  -126, -126, 127, -125,
-                                   -126, 127, -127, -127, -57,  -30,  127, 80};
+const int8_t kOutputDenseWeights[24] = {
+    127,  127,  127, 127,  127,  20,  127,  -126, -126, -54, 14,  125,
+    -126, -126, 127, -125, -126, 127, -127, -127, -57,  -30, 127, 80};
 
-const int8_t kOutputBias[1] = {-50};
+const int8_t kOutputDenseBias[1] = {-50};
 
 }  // namespace rnnoise

third_party/rnnoise/src/rnn_vad_weights.h

@@ -5,13 +5,24 @@
 
 namespace rnnoise {
 
+// Weights scaling factor.
+extern const float kWeightsScale = 1.f / 256.f;
+
+// Input layer (dense).
+extern const size_t kInputLayerOutputSize = 24;
 extern const int8_t kInputDenseWeights[1008];
 extern const int8_t kInputDenseBias[24];
+
+// Hidden layer (GRU).
+extern const size_t kHiddenLayerOutputSize = 24;
 extern const int8_t kHiddenGruWeights[1728];
 extern const int8_t kHiddenGruRecurrentWeights[1728];
 extern const int8_t kHiddenGruBias[72];
-extern const int8_t kOutputWeights[24];
-extern const int8_t kOutputBias[1];
+
+// Output layer (dense).
+extern const size_t kOutputLayerOutputSize = 1;
+extern const int8_t kOutputDenseWeights[24];
+extern const int8_t kOutputDenseBias[1];
 
 }  // namespace rnnoise