Support floating-point audio output for Linux

media/base/audio_bus.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/audio_bus.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <limits>
@@ skipping 319 matching lines @@
 
 void AudioBus::Scale(float volume) {
   if (volume > 0 && volume != 1) {
     for (int i = 0; i < channels(); ++i)
       vector_math::FMUL(channel(i), volume, frames(), channel(i));
   } else if (volume == 0) {
     Zero();
   }
 }
 
+void AudioBus::Clamp() {

[DaleCurtis, 2016/11/01 23:07:53]

No need IIRC, interleave should take care of this.

[Raymond Toy, 2016/11/01 23:18:50]

You're right. I tested with a webaudio manual test that intentionally overflows
to test clipping and the output is clipped as expected.

+  for (int ch = 0; ch < channels(); ++ch) {
+    // Replace NaN with 0 and then clamp the data to [-1, 1].
+    float* channel_data = channel(ch);
+    for (int k = 0; k < frames_; ++k) {
+      float value = channel_data[k];
+      if (value < -1)
+        value = -1;
+      else if (value > 1)
+        value = 1;
+      else if (std::isnan(value))
+        value = 0;
+      channel_data[k] = value;
+    }
+  }
+}
+
 void AudioBus::SwapChannels(int a, int b) {
   DCHECK(a < channels() && a >= 0);
   DCHECK(b < channels() && b >= 0);
   DCHECK_NE(a, b);
   std::swap(channel_data_[a], channel_data_[b]);
 }
 
 scoped_refptr<AudioBusRefCounted> AudioBusRefCounted::Create(
     int channels, int frames) {
   return scoped_refptr<AudioBusRefCounted>(
       new AudioBusRefCounted(channels, frames));
 }
 
 AudioBusRefCounted::AudioBusRefCounted(int channels, int frames)
     : AudioBus(channels, frames) {}
 
 AudioBusRefCounted::~AudioBusRefCounted() {}
 
 }  // namespace media