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// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "third_party/blink/renderer/modules/webaudio/channel_merger_handler.h"
#include "third_party/blink/renderer/modules/webaudio/audio_node_input.h"
#include "third_party/blink/renderer/modules/webaudio/audio_node_output.h"
#include "third_party/blink/renderer/modules/webaudio/base_audio_context.h"
#include "third_party/blink/renderer/platform/bindings/exception_state.h"
namespace blink {
namespace {
constexpr unsigned kNumberOfInputChannels = 1;
} // namespace
ChannelMergerHandler::ChannelMergerHandler(AudioNode& node,
float sample_rate,
unsigned number_of_inputs)
: AudioHandler(NodeType::kNodeTypeChannelMerger, node, sample_rate) {
// These properties are fixed for the node and cannot be changed by user.
channel_count_ = kNumberOfInputChannels;
SetInternalChannelCountMode(V8ChannelCountMode::Enum::kExplicit);
// Create the requested number of inputs.
for (unsigned i = 0; i < number_of_inputs; ++i) {
AddInput();
}
// Create the output with the requested number of channels.
AddOutput(number_of_inputs);
Initialize();
// Until something is connected, we're not actively processing, so disable
// outputs so that we produce a single channel of silence. The graph lock is
// needed to be able to disable outputs.
DeferredTaskHandler::GraphAutoLocker context_locker(Context());
DisableOutputs();
}
scoped_refptr<ChannelMergerHandler> ChannelMergerHandler::Create(
AudioNode& node,
float sample_rate,
unsigned number_of_inputs) {
return base::AdoptRef(
new ChannelMergerHandler(node, sample_rate, number_of_inputs));
}
void ChannelMergerHandler::Process(uint32_t frames_to_process) {
AudioNodeOutput& output = Output(0);
DCHECK_EQ(frames_to_process, output.Bus()->length());
unsigned number_of_output_channels = output.NumberOfChannels();
DCHECK_EQ(NumberOfInputs(), number_of_output_channels);
// Merge multiple inputs into one output.
for (unsigned i = 0; i < number_of_output_channels; ++i) {
AudioNodeInput& input = Input(i);
DCHECK_EQ(input.NumberOfChannels(), 1u);
AudioChannel* output_channel = output.Bus()->Channel(i);
if (input.IsConnected()) {
// The mixing rules will be applied so multiple channels are down-
// mixed to mono (when the mixing rule is defined). Note that only
// the first channel will be taken for the undefined input channel
// layout.
//
// See:
// http://webaudio.github.io/web-audio-api/#channel-up-mixing-and-down-mixing
AudioChannel* input_channel = input.Bus()->Channel(0);
output_channel->CopyFrom(input_channel);
} else {
// If input is unconnected, fill zeros in the channel.
output_channel->Zero();
}
}
}
void ChannelMergerHandler::SetChannelCount(unsigned channel_count,
ExceptionState& exception_state) {
DCHECK(IsMainThread());
DeferredTaskHandler::GraphAutoLocker locker(Context());
// channelCount must be 1.
if (channel_count != 1) {
exception_state.ThrowDOMException(
DOMExceptionCode::kInvalidStateError,
"ChannelMerger: channelCount cannot be changed from 1");
}
}
void ChannelMergerHandler::SetChannelCountMode(
V8ChannelCountMode::Enum mode,
ExceptionState& exception_state) {
DCHECK(IsMainThread());
DeferredTaskHandler::GraphAutoLocker locker(Context());
// channcelCountMode must be 'explicit'.
if (mode != V8ChannelCountMode::Enum::kExplicit) {
exception_state.ThrowDOMException(
DOMExceptionCode::kInvalidStateError,
"ChannelMerger: channelCountMode cannot be changed from 'explicit'");
}
}
} // namespace blink
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