Enhance AudioSplicer to crossfade marked splice frames.

media/base/vector_math.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/base/vector_math.h"
 #include "media/base/vector_math_testing.h"
 
 #include <algorithm>
 
 #include "base/cpu.h"
@@ skipping 70 matching lines @@
   DCHECK_EQ(0u, reinterpret_cast<uintptr_t>(src) & (kRequiredAlignment - 1));
   DCHECK_EQ(0u, reinterpret_cast<uintptr_t>(dest) & (kRequiredAlignment - 1));
   return FMUL_FUNC(src, scale, len, dest);
 }
 
 void FMUL_C(const float src[], float scale, int len, float dest[]) {
   for (int i = 0; i < len; ++i)
     dest[i] = src[i] * scale;
 }
 
+void Crossfade(const float src[], int len, float dest[]) {
+  float cf_ratio = 0;
+  const float cf_increment = 1.0f / len;
+  for (int i = 0; i < len; ++i, cf_ratio += cf_increment)
+    dest[i] = (1.0f - cf_ratio) * src[i] + cf_ratio * dest[i];
+}
+
 std::pair<float, float> EWMAAndMaxPower(
     float initial_value, const float src[], int len, float smoothing_factor) {
   // Ensure |src| is 16-byte aligned.
   DCHECK_EQ(0u, reinterpret_cast<uintptr_t>(src) & (kRequiredAlignment - 1));
   return EWMAAndMaxPower_FUNC(initial_value, src, len, smoothing_factor);
 }
 
 std::pair<float, float> EWMAAndMaxPower_C(
     float initial_value, const float src[], int len, float smoothing_factor) {
   std::pair<float, float> result(initial_value, 0.0f);
@@ skipping 96 matching lines @@
     result.first += sample_squared * smoothing_factor;
     result.second = std::max(result.second, sample_squared);
   }
 
   return result;
 }
 #endif
 
 }  // namespace vector_math
 }  // namespace media