Moved buffering of farend into the EchoSubtraction method.

webrtc/modules/audio_processing/aec/aec_core.c

Index: webrtc/modules/audio_processing/aec/aec_core.c
diff --git a/webrtc/modules/audio_processing/aec/aec_core.c b/webrtc/modules/audio_processing/aec/aec_core.c
index 26e13bc2c2dac54529e129c62ab964e3befd282d..e932e37f12464f0d48b1d235355c8dd236484a03 100644
--- a/webrtc/modules/audio_processing/aec/aec_core.c
+++ b/webrtc/modules/audio_processing/aec/aec_core.c
@@ -899,20 +899,22 @@ static int SignalBasedDelayCorrection(AecCore* self) {
   return delay_correction;
 }
 
-static void EchoSubtraction(
-    AecCore* aec,
-    int num_partitions,
-    int x_fft_buf_block_pos,
-    int metrics_mode,
-    int extended_filter_enabled,
-    float normal_mu,
-    float normal_error_threshold,
-    float x_fft_buf[2][kExtendedNumPartitions * PART_LEN1],
-    float* const y,
-    float x_pow[PART_LEN1],
-    float h_fft_buf[2][kExtendedNumPartitions * PART_LEN1],
-    PowerLevel* linout_level,
-    float echo_subtractor_output[PART_LEN]) {
+static void EchoSubtraction(AecCore* aec,
+                            int num_partitions,
+                            int metrics_mode,
+                            int extended_filter_enabled,
+                            float normal_mu,
+                            float normal_error_threshold,
+                            float* x_fft,
+                            int* x_fft_buf_block_pos,
+                            float x_fft_buf[2]
+                                           [kExtendedNumPartitions * PART_LEN1],
+                            float* const y,
+                            float x_pow[PART_LEN1],
+                            float h_fft_buf[2]
+                                           [kExtendedNumPartitions * PART_LEN1],
+                            PowerLevel* linout_level,
+                            float echo_subtractor_output[PART_LEN]) {

[ivoc, 2016/02/05 09:05:04]

Although I noticed that most functions in the file don't have this, I was
thinking that a bit of documentation on what the input/output variables are and
do would be useful. What do you think?

[peah-webrtc, 2016/02/05 10:19:49]

Great point! That would definitely make sense. I'm a bit hesitant to add it
right now, though, as this is code that is going through, and for several months
will continue to go through, a lot of changes. Therefore I'll not add any
comments at this point but instead wait with the comments until a later stage.

   float s_fft[2][PART_LEN1];
   float e_extended[PART_LEN2];
   float s_extended[PART_LEN2];
@@ -920,6 +922,19 @@ static void EchoSubtraction(
   float e[PART_LEN];
   float e_fft[2][PART_LEN1];
   int i;
+
+  // Update the x_fft_buf block position.
+  (*x_fft_buf_block_pos)--;
+  if ((*x_fft_buf_block_pos) == -1) {
+    *x_fft_buf_block_pos = num_partitions - 1;
+  }
+
+  // Buffer x_fft.
+  memcpy(x_fft_buf[0] + (*x_fft_buf_block_pos) * PART_LEN1, x_fft,
+         sizeof(float) * PART_LEN1);
+  memcpy(x_fft_buf[1] + (*x_fft_buf_block_pos) * PART_LEN1, &x_fft[PART_LEN1],
+         sizeof(float) * PART_LEN1);
+
   memset(s_fft, 0, sizeof(s_fft));
 
   // Conditionally reset the echo subtraction filter if the filter has diverged
@@ -931,11 +946,8 @@ static void EchoSubtraction(
   }
 
   // Produce echo estimate s_fft.
-  WebRtcAec_FilterFar(num_partitions,
-                      x_fft_buf_block_pos,
-                      x_fft_buf,
-                      h_fft_buf,
-                      s_fft);
+  WebRtcAec_FilterFar(num_partitions, *x_fft_buf_block_pos, x_fft_buf,
+                      h_fft_buf, s_fft);
 
   // Compute the time-domain echo estimate s.
   ScaledInverseFft(s_fft, s_extended, 2.0f, 0);
@@ -968,11 +980,8 @@ static void EchoSubtraction(
                              normal_error_threshold,
                              x_pow,
                              e_fft);
-  WebRtcAec_FilterAdaptation(num_partitions,
-                             x_fft_buf_block_pos,
-                             x_fft_buf,
-                             e_fft,
-                             h_fft_buf);
+  WebRtcAec_FilterAdaptation(num_partitions, *x_fft_buf_block_pos, x_fft_buf,
+                             e_fft, h_fft_buf);
   memcpy(echo_subtractor_output, e, sizeof(float) * PART_LEN);
 }
 
@@ -1225,7 +1234,7 @@ static void ProcessBlock(AecCore* aec) {
   size_t i;
 
   float fft[PART_LEN2];
-  float xf[2][PART_LEN1];
+  float x_fft[2][PART_LEN1];
   float df[2][PART_LEN1];
   float far_spectrum = 0.0f;
   float near_spectrum = 0.0f;
@@ -1248,7 +1257,7 @@ static void ProcessBlock(AecCore* aec) {
   float output[PART_LEN];
   float outputH[NUM_HIGH_BANDS_MAX][PART_LEN];
   float* outputH_ptr[NUM_HIGH_BANDS_MAX];
-  float* xf_ptr = NULL;
+  float* x_fft_ptr = NULL;
 
   for (i = 0; i < NUM_HIGH_BANDS_MAX; ++i) {
     outputH_ptr[i] = outputH[i];
@@ -1281,8 +1290,8 @@ static void ProcessBlock(AecCore* aec) {
 
   // Convert far-end signal to the frequency domain.
   memcpy(fft, farend_ptr, sizeof(float) * PART_LEN2);
-  Fft(fft, xf);
-  xf_ptr = &xf[0][0];
+  Fft(fft, x_fft);
+  x_fft_ptr = &x_fft[0][0];
 
   // Near fft
   memcpy(fft, aec->dBuf, sizeof(float) * PART_LEN2);
@@ -1296,8 +1305,8 @@ static void ProcessBlock(AecCore* aec) {
 
   // Power smoothing
   for (i = 0; i < PART_LEN1; i++) {
-    far_spectrum = (xf_ptr[i] * xf_ptr[i]) +
-                   (xf_ptr[PART_LEN1 + i] * xf_ptr[PART_LEN1 + i]);
+    far_spectrum = (x_fft_ptr[i] * x_fft_ptr[i]) +
+                   (x_fft_ptr[PART_LEN1 + i] * x_fft_ptr[PART_LEN1 + i]);
     aec->xPow[i] =
         gPow[0] * aec->xPow[i] + gPow[1] * aec->num_partitions * far_spectrum;
     // Calculate absolute spectra
@@ -1356,34 +1365,12 @@ static void ProcessBlock(AecCore* aec) {
     }
   }
 
-  // Update the xfBuf block position.
-  aec->xfBufBlockPos--;
-  if (aec->xfBufBlockPos == -1) {
-    aec->xfBufBlockPos = aec->num_partitions - 1;
-  }
-
-  // Buffer xf
-  memcpy(aec->xfBuf[0] + aec->xfBufBlockPos * PART_LEN1,
-         xf_ptr,
-         sizeof(float) * PART_LEN1);
-  memcpy(aec->xfBuf[1] + aec->xfBufBlockPos * PART_LEN1,
-         &xf_ptr[PART_LEN1],
-         sizeof(float) * PART_LEN1);
-
   // Perform echo subtraction.
-  EchoSubtraction(aec,
-                  aec->num_partitions,
-                  aec->xfBufBlockPos,
-                  aec->metricsMode,
-                  aec->extended_filter_enabled,
-                  aec->normal_mu,
-                  aec->normal_error_threshold,
-                  aec->xfBuf,
-                  nearend_ptr,
-                  aec->xPow,
-                  aec->wfBuf,
-                  &aec->linoutlevel,
-                  echo_subtractor_output);
+  EchoSubtraction(aec, aec->num_partitions, aec->metricsMode,
+                  aec->extended_filter_enabled, aec->normal_mu,
+                  aec->normal_error_threshold, &x_fft[0][0],
+                  &aec->xfBufBlockPos, aec->xfBuf, nearend_ptr, aec->xPow,
+                  aec->wfBuf, &aec->linoutlevel, echo_subtractor_output);
 
   RTC_AEC_DEBUG_WAV_WRITE(aec->outLinearFile, echo_subtractor_output, PART_LEN);