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// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/351564777): Remove this and convert code to safer constructs.
#pragma allow_unsafe_buffers
#endif
#include "third_party/blink/renderer/platform/audio/stereo_panner.h"
#include <algorithm>
#include <memory>
#include "base/memory/ptr_util.h"
#include "third_party/blink/renderer/platform/audio/audio_bus.h"
#include "third_party/blink/renderer/platform/audio/audio_utilities.h"
#include "third_party/blink/renderer/platform/wtf/math_extras.h"
#include "third_party/fdlibm/ieee754.h"
namespace blink {
// Implement equal-power panning algorithm for mono or stereo input.
// See: http://webaudio.github.io/web-audio-api/#panning-algorithm
StereoPanner::StereoPanner(float sample_rate) {}
void StereoPanner::PanWithSampleAccurateValues(const AudioBus* input_bus,
AudioBus* output_bus,
const float* pan_values,
uint32_t frames_to_process) {
DCHECK(input_bus);
DCHECK_LE(frames_to_process, input_bus->length());
DCHECK_GE(input_bus->NumberOfChannels(), 1u);
DCHECK_LE(input_bus->NumberOfChannels(), 2u);
unsigned number_of_input_channels = input_bus->NumberOfChannels();
DCHECK(output_bus);
DCHECK_EQ(output_bus->NumberOfChannels(), 2u);
DCHECK_LE(frames_to_process, output_bus->length());
const float* source_l = input_bus->Channel(0)->Data();
const float* source_r =
number_of_input_channels > 1 ? input_bus->Channel(1)->Data() : source_l;
float* destination_l =
output_bus->ChannelByType(AudioBus::kChannelLeft)->MutableData();
float* destination_r =
output_bus->ChannelByType(AudioBus::kChannelRight)->MutableData();
if (!source_l || !source_r || !destination_l || !destination_r) {
return;
}
double gain_l, gain_r, pan_radian;
int n = frames_to_process;
if (number_of_input_channels == 1) { // For mono source case.
while (n--) {
float input_l = *source_l++;
double pan = ClampTo(*pan_values++, -1.0, 1.0);
// Pan from left to right [-1; 1] will be normalized as [0; 1].
pan_radian = (pan * 0.5 + 0.5) * kPiOverTwoDouble;
gain_l = fdlibm::cos(pan_radian);
gain_r = fdlibm::sin(pan_radian);
*destination_l++ = static_cast<float>(input_l * gain_l);
*destination_r++ = static_cast<float>(input_l * gain_r);
}
} else { // For stereo source case.
while (n--) {
float input_l = *source_l++;
float input_r = *source_r++;
double pan = ClampTo(*pan_values++, -1.0, 1.0);
// Normalize [-1; 0] to [0; 1]. Do nothing when [0; 1].
pan_radian = (pan <= 0 ? pan + 1 : pan) * kPiOverTwoDouble;
gain_l = fdlibm::cos(pan_radian);
gain_r = fdlibm::sin(pan_radian);
if (pan <= 0) {
*destination_l++ = static_cast<float>(input_l + input_r * gain_l);
*destination_r++ = static_cast<float>(input_r * gain_r);
} else {
*destination_l++ = static_cast<float>(input_l * gain_l);
*destination_r++ = static_cast<float>(input_r + input_l * gain_r);
}
}
}
}
void StereoPanner::PanToTargetValue(const AudioBus* input_bus,
AudioBus* output_bus,
float pan_value,
uint32_t frames_to_process) {
DCHECK(input_bus);
DCHECK_LE(frames_to_process, input_bus->length());
DCHECK_GE(input_bus->NumberOfChannels(), 1u);
DCHECK_LE(input_bus->NumberOfChannels(), 2u);
unsigned number_of_input_channels = input_bus->NumberOfChannels();
DCHECK(output_bus);
DCHECK_EQ(output_bus->NumberOfChannels(), 2u);
DCHECK_LE(frames_to_process, output_bus->length());
const float* source_l = input_bus->Channel(0)->Data();
const float* source_r =
number_of_input_channels > 1 ? input_bus->Channel(1)->Data() : source_l;
float* destination_l =
output_bus->ChannelByType(AudioBus::kChannelLeft)->MutableData();
float* destination_r =
output_bus->ChannelByType(AudioBus::kChannelRight)->MutableData();
if (!source_l || !source_r || !destination_l || !destination_r) {
return;
}
float target_pan = ClampTo(pan_value, -1.0, 1.0);
int n = frames_to_process;
if (number_of_input_channels == 1) { // For mono source case.
// Pan from left to right [-1; 1] will be normalized as [0; 1].
double pan_radian = (target_pan * 0.5 + 0.5) * kPiOverTwoDouble;
double gain_l = fdlibm::cos(pan_radian);
double gain_r = fdlibm::sin(pan_radian);
// TODO(rtoy): This can be vectorized using vector_math::Vsmul
while (n--) {
float input_l = *source_l++;
*destination_l++ = static_cast<float>(input_l * gain_l);
*destination_r++ = static_cast<float>(input_l * gain_r);
}
} else { // For stereo source case.
// Normalize [-1; 0] to [0; 1] for the left pan position (<= 0), and
// do nothing when [0; 1].
double pan_radian =
(target_pan <= 0 ? target_pan + 1 : target_pan) * kPiOverTwoDouble;
double gain_l = fdlibm::cos(pan_radian);
double gain_r = fdlibm::sin(pan_radian);
// TODO(rtoy): Consider moving the if statement outside the loop
// since |target_pan| is constant inside the loop.
while (n--) {
float input_l = *source_l++;
float input_r = *source_r++;
if (target_pan <= 0) {
// When [-1; 0], keep left channel intact and equal-power pan the
// right channel only.
*destination_l++ = static_cast<float>(input_l + input_r * gain_l);
*destination_r++ = static_cast<float>(input_r * gain_r);
} else {
// When [0; 1], keep right channel intact and equal-power pan the
// left channel only.
*destination_l++ = static_cast<float>(input_l * gain_l);
*destination_r++ = static_cast<float>(input_r + input_l * gain_r);
}
}
}
}
} // namespace blink
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