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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-*/
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
#include "MediaEngineWebRTCAudio.h"
#include <stdio.h>
#include <algorithm>
#include "AudioConverter.h"
#include "MediaManager.h"
#include "MediaTrackGraph.h"
#include "MediaTrackConstraints.h"
#include "mozilla/Assertions.h"
#include "mozilla/ErrorNames.h"
#include "nsIDUtils.h"
#include "transport/runnable_utils.h"
#include "Tracing.h"
#include "mozilla/Sprintf.h"
#include "mozilla/Logging.h"
#include "api/audio/echo_canceller3_factory.h"
#include "common_audio/include/audio_util.h"
#include "modules/audio_processing/include/audio_processing.h"
using namespace webrtc;
// These are restrictions from the webrtc.org code
#define MAX_CHANNELS 2
#define MONO 1
#define MAX_SAMPLING_FREQ 48000 // Hz - multiple of 100
namespace mozilla {
using dom::MediaSourceEnum;
extern LazyLogModule gMediaManagerLog;
#define LOG(...) MOZ_LOG(gMediaManagerLog, LogLevel::Debug, (__VA_ARGS__))
#define LOG_FRAME(...) \
MOZ_LOG(gMediaManagerLog, LogLevel::Verbose, (__VA_ARGS__))
#define LOG_ERROR(...) MOZ_LOG(gMediaManagerLog, LogLevel::Error, (__VA_ARGS__))
/**
* WebRTC Microphone MediaEngineSource.
*/
MediaEngineWebRTCMicrophoneSource::MediaEngineWebRTCMicrophoneSource(
const MediaDevice* aMediaDevice)
: mPrincipal(PRINCIPAL_HANDLE_NONE),
mDeviceInfo(aMediaDevice->mAudioDeviceInfo),
mDeviceMaxChannelCount(mDeviceInfo->MaxChannels()),
mSettings(new nsMainThreadPtrHolder<
media::Refcountable<dom::MediaTrackSettings>>(
"MediaEngineWebRTCMicrophoneSource::mSettings",
new media::Refcountable<dom::MediaTrackSettings>(),
// Non-strict means it won't assert main thread for us.
// It would be great if it did but we're already on the media thread.
/* aStrict = */ false)) {
MOZ_ASSERT(aMediaDevice->mMediaSource == MediaSourceEnum::Microphone);
#ifndef ANDROID
MOZ_ASSERT(mDeviceInfo->DeviceID());
#endif
// We'll init lazily as needed
mSettings->mEchoCancellation.Construct(0);
mSettings->mAutoGainControl.Construct(0);
mSettings->mNoiseSuppression.Construct(0);
mSettings->mChannelCount.Construct(0);
mState = kReleased;
}
nsresult MediaEngineWebRTCMicrophoneSource::EvaluateSettings(
const NormalizedConstraints& aConstraintsUpdate,
const MediaEnginePrefs& aInPrefs, MediaEnginePrefs* aOutPrefs,
const char** aOutBadConstraint) {
AssertIsOnOwningThread();
FlattenedConstraints c(aConstraintsUpdate);
MediaEnginePrefs prefs = aInPrefs;
prefs.mAecOn = c.mEchoCancellation.Get(aInPrefs.mAecOn);
prefs.mAgcOn = c.mAutoGainControl.Get(aInPrefs.mAgcOn && prefs.mAecOn);
prefs.mNoiseOn = c.mNoiseSuppression.Get(aInPrefs.mNoiseOn && prefs.mAecOn);
// Determine an actual channel count to use for this source. Three factors at
// play here: the device capabilities, the constraints passed in by content,
// and a pref that can force things (for testing)
int32_t maxChannels = static_cast<int32_t>(mDeviceInfo->MaxChannels());
// First, check channelCount violation wrt constraints. This fails in case of
// error.
if (c.mChannelCount.mMin > maxChannels) {
*aOutBadConstraint = "channelCount";
return NS_ERROR_FAILURE;
}
// A pref can force the channel count to use. If the pref has a value of zero
// or lower, it has no effect.
if (aInPrefs.mChannels <= 0) {
prefs.mChannels = maxChannels;
}
// Get the number of channels asked for by content, and clamp it between the
// pref and the maximum number of channels that the device supports.
prefs.mChannels = c.mChannelCount.Get(std::min(prefs.mChannels, maxChannels));
prefs.mChannels = std::max(1, std::min(prefs.mChannels, maxChannels));
LOG("Mic source %p Audio config: aec: %s, agc: %s, noise: %s, channels: %d",
this, prefs.mAecOn ? "on" : "off", prefs.mAgcOn ? "on" : "off",
prefs.mNoiseOn ? "on" : "off", prefs.mChannels);
*aOutPrefs = prefs;
return NS_OK;
}
nsresult MediaEngineWebRTCMicrophoneSource::Reconfigure(
const dom::MediaTrackConstraints& aConstraints,
const MediaEnginePrefs& aPrefs, const char** aOutBadConstraint) {
AssertIsOnOwningThread();
MOZ_ASSERT(mTrack);
LOG("Mic source %p Reconfigure ", this);
NormalizedConstraints constraints(aConstraints);
MediaEnginePrefs outputPrefs;
nsresult rv =
EvaluateSettings(constraints, aPrefs, &outputPrefs, aOutBadConstraint);
if (NS_FAILED(rv)) {
if (aOutBadConstraint) {
return NS_ERROR_INVALID_ARG;
}
nsAutoCString name;
GetErrorName(rv, name);
LOG("Mic source %p Reconfigure() failed unexpectedly. rv=%s", this,
name.Data());
Stop();
return NS_ERROR_UNEXPECTED;
}
ApplySettings(outputPrefs);
mCurrentPrefs = outputPrefs;
return NS_OK;
}
AudioProcessing::Config AudioInputProcessing::ConfigForPrefs(
const MediaEnginePrefs& aPrefs) {
AudioProcessing::Config config;
config.pipeline.multi_channel_render = true;
config.pipeline.multi_channel_capture = true;
config.echo_canceller.enabled = aPrefs.mAecOn;
config.echo_canceller.mobile_mode = aPrefs.mUseAecMobile;
if ((config.gain_controller1.enabled =
aPrefs.mAgcOn && !aPrefs.mAgc2Forced)) {
auto mode = static_cast<AudioProcessing::Config::GainController1::Mode>(
aPrefs.mAgc);
if (mode != AudioProcessing::Config::GainController1::kAdaptiveAnalog &&
mode != AudioProcessing::Config::GainController1::kAdaptiveDigital &&
mode != AudioProcessing::Config::GainController1::kFixedDigital) {
LOG_ERROR("AudioInputProcessing %p Attempt to set invalid AGC mode %d",
this, static_cast<int>(mode));
mode = AudioProcessing::Config::GainController1::kAdaptiveDigital;
}
#if defined(WEBRTC_IOS) || defined(ATA) || defined(WEBRTC_ANDROID)
if (mode == AudioProcessing::Config::GainController1::kAdaptiveAnalog) {
LOG_ERROR(
"AudioInputProcessing %p Invalid AGC mode kAdaptiveAnalog on "
"mobile",
this);
MOZ_ASSERT_UNREACHABLE(
"Bad pref set in all.js or in about:config"
" for the auto gain, on mobile.");
mode = AudioProcessing::Config::GainController1::kFixedDigital;
}
#endif
config.gain_controller1.mode = mode;
}
config.gain_controller2.enabled =
config.gain_controller2.adaptive_digital.enabled =
aPrefs.mAgcOn && aPrefs.mAgc2Forced;
if ((config.noise_suppression.enabled = aPrefs.mNoiseOn)) {
auto level = static_cast<AudioProcessing::Config::NoiseSuppression::Level>(
aPrefs.mNoise);
if (level != AudioProcessing::Config::NoiseSuppression::kLow &&
level != AudioProcessing::Config::NoiseSuppression::kModerate &&
level != AudioProcessing::Config::NoiseSuppression::kHigh &&
level != AudioProcessing::Config::NoiseSuppression::kVeryHigh) {
LOG_ERROR(
"AudioInputProcessing %p Attempt to set invalid noise suppression "
"level %d",
this, static_cast<int>(level));
level = AudioProcessing::Config::NoiseSuppression::kModerate;
}
config.noise_suppression.level = level;
}
config.transient_suppression.enabled = aPrefs.mTransientOn;
config.high_pass_filter.enabled = aPrefs.mHPFOn;
return config;
}
void MediaEngineWebRTCMicrophoneSource::ApplySettings(
const MediaEnginePrefs& aPrefs) {
AssertIsOnOwningThread();
TRACE("ApplySettings");
MOZ_ASSERT(
mTrack,
"ApplySetting is to be called only after SetTrack has been called");
RefPtr<MediaEngineWebRTCMicrophoneSource> that = this;
CubebUtils::AudioDeviceID deviceID = mDeviceInfo->DeviceID();
NS_DispatchToMainThread(NS_NewRunnableFunction(
__func__, [this, that, deviceID, track = mTrack, prefs = aPrefs] {
mSettings->mEchoCancellation.Value() = prefs.mAecOn;
mSettings->mAutoGainControl.Value() = prefs.mAgcOn;
mSettings->mNoiseSuppression.Value() = prefs.mNoiseOn;
mSettings->mChannelCount.Value() = prefs.mChannels;
if (track->IsDestroyed()) {
return;
}
track->QueueControlMessageWithNoShutdown(
[track, deviceID, prefs, inputProcessing = mInputProcessing] {
inputProcessing->ApplySettings(track->Graph(), deviceID, prefs);
});
}));
}
nsresult MediaEngineWebRTCMicrophoneSource::Allocate(
const dom::MediaTrackConstraints& aConstraints,
const MediaEnginePrefs& aPrefs, uint64_t aWindowID,
const char** aOutBadConstraint) {
AssertIsOnOwningThread();
mState = kAllocated;
NormalizedConstraints normalized(aConstraints);
MediaEnginePrefs outputPrefs;
nsresult rv =
EvaluateSettings(normalized, aPrefs, &outputPrefs, aOutBadConstraint);
if (NS_FAILED(rv)) {
return rv;
}
NS_DispatchToMainThread(NS_NewRunnableFunction(
__func__, [settings = mSettings, prefs = outputPrefs] {
settings->mEchoCancellation.Value() = prefs.mAecOn;
settings->mAutoGainControl.Value() = prefs.mAgcOn;
settings->mNoiseSuppression.Value() = prefs.mNoiseOn;
settings->mChannelCount.Value() = prefs.mChannels;
}));
mCurrentPrefs = outputPrefs;
return rv;
}
nsresult MediaEngineWebRTCMicrophoneSource::Deallocate() {
AssertIsOnOwningThread();
MOZ_ASSERT(mState == kStopped || mState == kAllocated);
if (mTrack) {
NS_DispatchToMainThread(NS_NewRunnableFunction(
__func__,
[track = std::move(mTrack), inputProcessing = mInputProcessing] {
if (track->IsDestroyed()) {
// This track has already been destroyed on main thread by its
// DOMMediaStream. No cleanup left to do.
return;
}
track->QueueControlMessageWithNoShutdown([inputProcessing] {
TRACE("mInputProcessing::End");
inputProcessing->End();
});
}));
}
// Reset all state. This is not strictly necessary, this instance will get
// destroyed soon.
mTrack = nullptr;
mPrincipal = PRINCIPAL_HANDLE_NONE;
// If empty, no callbacks to deliver data should be occuring
MOZ_ASSERT(mState != kReleased, "Source not allocated");
MOZ_ASSERT(mState != kStarted, "Source not stopped");
mState = kReleased;
LOG("Mic source %p Audio device %s deallocated", this,
NS_ConvertUTF16toUTF8(mDeviceInfo->Name()).get());
return NS_OK;
}
void MediaEngineWebRTCMicrophoneSource::SetTrack(
const RefPtr<MediaTrack>& aTrack, const PrincipalHandle& aPrincipal) {
AssertIsOnOwningThread();
MOZ_ASSERT(aTrack);
MOZ_ASSERT(aTrack->AsAudioProcessingTrack());
MOZ_ASSERT(!mTrack);
MOZ_ASSERT(mPrincipal == PRINCIPAL_HANDLE_NONE);
mTrack = aTrack->AsAudioProcessingTrack();
mPrincipal = aPrincipal;
mInputProcessing =
MakeAndAddRef<AudioInputProcessing>(mDeviceMaxChannelCount);
NS_DispatchToMainThread(NS_NewRunnableFunction(
__func__, [track = mTrack, processing = mInputProcessing]() mutable {
track->SetInputProcessing(std::move(processing));
track->Resume(); // Suspended by MediaManager
}));
LOG("Mic source %p Track %p registered for microphone capture", this,
aTrack.get());
}
nsresult MediaEngineWebRTCMicrophoneSource::Start() {
AssertIsOnOwningThread();
// This spans setting both the enabled state and mState.
if (mState == kStarted) {
return NS_OK;
}
MOZ_ASSERT(mState == kAllocated || mState == kStopped);
ApplySettings(mCurrentPrefs);
CubebUtils::AudioDeviceID deviceID = mDeviceInfo->DeviceID();
NS_DispatchToMainThread(NS_NewRunnableFunction(
__func__, [inputProcessing = mInputProcessing, deviceID, track = mTrack,
principal = mPrincipal] {
if (track->IsDestroyed()) {
return;
}
track->QueueControlMessageWithNoShutdown([track, inputProcessing] {
TRACE("mInputProcessing::Start");
inputProcessing->Start(track->Graph());
});
track->ConnectDeviceInput(deviceID, inputProcessing.get(), principal);
}));
MOZ_ASSERT(mState != kReleased);
mState = kStarted;
return NS_OK;
}
nsresult MediaEngineWebRTCMicrophoneSource::Stop() {
AssertIsOnOwningThread();
LOG("Mic source %p Stop()", this);
MOZ_ASSERT(mTrack, "SetTrack must have been called before ::Stop");
if (mState == kStopped) {
// Already stopped - this is allowed
return NS_OK;
}
NS_DispatchToMainThread(NS_NewRunnableFunction(
__func__, [inputProcessing = mInputProcessing, deviceInfo = mDeviceInfo,
track = mTrack] {
if (track->IsDestroyed()) {
return;
}
MOZ_ASSERT(track->DeviceId().value() == deviceInfo->DeviceID());
track->DisconnectDeviceInput();
track->QueueControlMessageWithNoShutdown([track, inputProcessing] {
TRACE("mInputProcessing::Stop");
inputProcessing->Stop(track->Graph());
});
}));
MOZ_ASSERT(mState == kStarted, "Should be started when stopping");
mState = kStopped;
return NS_OK;
}
void MediaEngineWebRTCMicrophoneSource::GetSettings(
dom::MediaTrackSettings& aOutSettings) const {
MOZ_ASSERT(NS_IsMainThread());
aOutSettings = *mSettings;
}
AudioInputProcessing::AudioInputProcessing(uint32_t aMaxChannelCount)
: mInputDownmixBuffer(MAX_SAMPLING_FREQ * MAX_CHANNELS / 100),
mEnabled(false),
mEnded(false),
mPacketCount(0) {
mSettings.mChannels = static_cast<int32_t>(std::min<uint32_t>(
std::numeric_limits<int32_t>::max(), aMaxChannelCount));
}
void AudioInputProcessing::Disconnect(MediaTrackGraph* aGraph) {
// This method is just for asserts.
aGraph->AssertOnGraphThread();
}
bool AudioInputProcessing::IsPassThrough(MediaTrackGraph* aGraph) const {
aGraph->AssertOnGraphThread();
// The high-pass filter is not taken into account when activating the
// pass through, since it's not controllable from content.
return !(mSettings.mAecOn || mSettings.mAgcOn || mSettings.mNoiseOn);
}
void AudioInputProcessing::PassThroughChanged(MediaTrackGraph* aGraph) {
aGraph->AssertOnGraphThread();
if (!mEnabled) {
MOZ_ASSERT(!mPacketizerInput);
return;
}
if (IsPassThrough(aGraph)) {
// Switching to pass-through. Clear state so that it doesn't affect any
// future processing, if re-enabled.
ResetAudioProcessing(aGraph);
} else {
// No longer pass-through. Processing will not use old state.
// Packetizer setup is deferred until needed.
MOZ_ASSERT(!mPacketizerInput);
}
}
uint32_t AudioInputProcessing::GetRequestedInputChannelCount() {
return mSettings.mChannels;
}
void AudioInputProcessing::RequestedInputChannelCountChanged(
MediaTrackGraph* aGraph, CubebUtils::AudioDeviceID aDeviceId) {
aGraph->ReevaluateInputDevice(aDeviceId);
}
void AudioInputProcessing::Start(MediaTrackGraph* aGraph) {
aGraph->AssertOnGraphThread();
if (mEnabled) {
return;
}
mEnabled = true;
MOZ_ASSERT(!mPacketizerInput);
}
void AudioInputProcessing::Stop(MediaTrackGraph* aGraph) {
aGraph->AssertOnGraphThread();
if (!mEnabled) {
return;
}
mEnabled = false;
if (IsPassThrough(aGraph)) {
return;
}
// Packetizer is active and we were just stopped. Stop the packetizer and
// processing.
ResetAudioProcessing(aGraph);
}
// The following is how how Process() works in pass-through and non-pass-through
// mode. In both mode, Process() outputs the same amount of the frames as its
// input data.
//
// I. In non-pass-through mode:
//
// We will use webrtc::AudioProcessing to process the input audio data in this
// mode. The data input in webrtc::AudioProcessing needs to be a 10ms chunk,
// while the input data passed to Process() is not necessary to have times of
// 10ms-chunk length. To divide the input data into 10ms chunks,
// mPacketizerInput is introduced.
//
// We will add one 10ms-chunk silence into the internal buffer before Process()
// works. Those extra frames is called pre-buffering. It aims to avoid glitches
// we may have when producing data in mPacketizerInput. Without pre-buffering,
// when the input data length is not 10ms-times, we could end up having no
// enough output needs since mPacketizerInput would keep some input data, which
// is the remainder of the 10ms-chunk length. To force processing those data
// left in mPacketizerInput, we would need to add some extra frames to make
// mPacketizerInput produce a 10ms-chunk. For example, if the sample rate is
// 44100 Hz, then the packet-size is 441 frames. When we only have 384 input
// frames, we would need to put additional 57 frames to mPacketizerInput to
// produce a packet. However, those extra 57 frames result in a glitch sound.
//
// By adding one 10ms-chunk silence in advance to the internal buffer, we won't
// need to add extra frames between the input data no matter what data length it
// is. The only drawback is the input data won't be processed and send to output
// immediately. Process() will consume pre-buffering data for its output first.
// The below describes how it works:
//
//
// Process()
// +-----------------------------+
// input D(N) | +--------+ +--------+ | output D(N)
// --------------|-->| P(N) |-->| S(N) |---|-------------->
// | +--------+ +--------+ |
// | packetizer mSegment |
// +-----------------------------+
// <------ internal buffer ------>
//
//
// D(N): number of frames from the input and the output needs in the N round
// Z: number of frames of a 10ms chunk(packet) in mPacketizerInput, Z >= 1
// (if Z = 1, packetizer has no effect)
// P(N): number of frames left in mPacketizerInput after the N round. Once the
// frames in packetizer >= Z, packetizer will produce a packet to
// mSegment, so P(N) = (P(N-1) + D(N)) % Z, 0 <= P(N) <= Z-1
// S(N): number of frames left in mSegment after the N round. The input D(N)
// frames will be passed to mPacketizerInput first, and then
// mPacketizerInput may append some packets to mSegment, so
// S(N) = S(N-1) + Z * floor((P(N-1) + D(N)) / Z) - D(N)
//
// At the first, we set P(0) = 0, S(0) = X, where X >= Z-1. X is the
// pre-buffering put in the internal buffer. With this settings, P(K) + S(K) = X
// always holds.
//
// Intuitively, this seems true: We put X frames in the internal buffer at
// first. If the data won't be blocked in packetizer, after the Process(), the
// internal buffer should still hold X frames since the number of frames coming
// from input is the same as the output needs. The key of having enough data for
// output needs, while the input data is piled up in packetizer, is by putting
// at least Z-1 frames as pre-buffering, since the maximum number of frames
// stuck in the packetizer before it can emit a packet is packet-size - 1.
// Otherwise, we don't have enough data for output if the new input data plus
// the data left in packetizer produces a smaller-than-10ms chunk, which will be
// left in packetizer. Thus we must have some pre-buffering frames in the
// mSegment to make up the length of the left chunk we need for output. This can
// also be told by by induction:
// (1) This holds when K = 0
// (2) Assume this holds when K = N: so P(N) + S(N) = X
// => P(N) + S(N) = X >= Z-1 => S(N) >= Z-1-P(N)
// (3) When K = N+1, we have D(N+1) input frames comes
// a. if P(N) + D(N+1) < Z, then packetizer has no enough data for one
// packet. No data produced by packertizer, so the mSegment now has
// S(N) >= Z-1-P(N) frames. Output needs D(N+1) < Z-P(N) frames. So it
// needs at most Z-P(N)-1 frames, and mSegment has enough frames for
// output, Then, P(N+1) = P(N) + D(N+1) and S(N+1) = S(N) - D(N+1)
// => P(N+1) + S(N+1) = P(N) + S(N) = X
// b. if P(N) + D(N+1) = Z, then packetizer will produce one packet for
// mSegment, so mSegment now has S(N) + Z frames. Output needs D(N+1)
// = Z-P(N) frames. S(N) has at least Z-1-P(N)+Z >= Z-P(N) frames, since
// Z >= 1. So mSegment has enough frames for output. Then, P(N+1) = 0 and
// S(N+1) = S(N) + Z - D(N+1) = S(N) + P(N)
// => P(N+1) + S(N+1) = P(N) + S(N) = X
// c. if P(N) + D(N+1) > Z, and let P(N) + D(N+1) = q * Z + r, where q >= 1
// and 0 <= r <= Z-1, then packetizer will produce can produce q packets
// for mSegment. Output needs D(N+1) = q * Z - P(N) + r frames and
// mSegment has S(N) + q * z >= q * z - P(N) + Z-1 >= q*z -P(N) + r,
// since r <= Z-1. So mSegment has enough frames for output. Then,
// P(N+1) = r and S(N+1) = S(N) + q * Z - D(N+1)
// => P(N+1) + S(N+1) = S(N) + (q * Z + r - D(N+1)) = S(N) + P(N) = X
// => P(K) + S(K) = X always holds
//
// Since P(K) + S(K) = X and P(K) is in [0, Z-1], the S(K) is in [X-Z+1, X]
// range. In our implementation, X is set to Z so S(K) is in [1, Z].
// By the above workflow, we always have enough data for output and no extra
// frames put into packetizer. It means we don't have any glitch!
//
// II. In pass-through mode:
//
// Process()
// +--------+
// input D(N) | | output D(N)
// -------------->-------->--------------->
// | |
// +--------+
//
// The D(N) frames of data are just forwarded from input to output without any
// processing
void AudioInputProcessing::Process(AudioProcessingTrack* aTrack,
GraphTime aFrom, GraphTime aTo,
AudioSegment* aInput,
AudioSegment* aOutput) {
aTrack->AssertOnGraphThread();
MOZ_ASSERT(aFrom <= aTo);
MOZ_ASSERT(!mEnded);
TrackTime need = aTo - aFrom;
if (need == 0) {
return;
}
MediaTrackGraph* graph = aTrack->Graph();
if (!mEnabled) {
LOG_FRAME("(Graph %p, Driver %p) AudioInputProcessing %p Filling %" PRId64
" frames of silence to output (disabled)",
graph, graph->CurrentDriver(), this, need);
aOutput->AppendNullData(need);
return;
}
MOZ_ASSERT(aInput->GetDuration() == need,
"Wrong data length from input port source");
if (IsPassThrough(graph)) {
LOG_FRAME(
"(Graph %p, Driver %p) AudioInputProcessing %p Forwarding %" PRId64
" frames of input data to output directly (PassThrough)",
graph, graph->CurrentDriver(), this, aInput->GetDuration());
aOutput->AppendSegment(aInput);
return;
}
// If the requested input channel count is updated, create a new
// packetizer. No need to change the pre-buffering since the rate is always
// the same. The frames left in the packetizer would be replaced by null
// data and then transferred to mSegment.
EnsurePacketizer(aTrack);
// Preconditions of the audio-processing logic.
MOZ_ASSERT(static_cast<uint32_t>(mSegment.GetDuration()) +
mPacketizerInput->FramesAvailable() ==
mPacketizerInput->mPacketSize);
// We pre-buffer mPacketSize frames, but the maximum number of frames stuck in
// the packetizer before it can emit a packet is mPacketSize-1. Thus that
// remaining 1 frame will always be present in mSegment.
MOZ_ASSERT(mSegment.GetDuration() >= 1);
MOZ_ASSERT(mSegment.GetDuration() <= mPacketizerInput->mPacketSize);
PacketizeAndProcess(aTrack, *aInput);
LOG_FRAME("(Graph %p, Driver %p) AudioInputProcessing %p Buffer has %" PRId64
" frames of data now, after packetizing and processing",
graph, graph->CurrentDriver(), this, mSegment.GetDuration());
// By setting pre-buffering to the number of frames of one packet, and
// because the maximum number of frames stuck in the packetizer before
// it can emit a packet is the mPacketSize-1, we always have at least
// one more frame than output needs.
MOZ_ASSERT(mSegment.GetDuration() > need);
aOutput->AppendSlice(mSegment, 0, need);
mSegment.RemoveLeading(need);
LOG_FRAME("(Graph %p, Driver %p) AudioInputProcessing %p moving %" PRId64
" frames of data to output, leaving %" PRId64 " frames in buffer",
graph, graph->CurrentDriver(), this, need, mSegment.GetDuration());
// Postconditions of the audio-processing logic.
MOZ_ASSERT(static_cast<uint32_t>(mSegment.GetDuration()) +
mPacketizerInput->FramesAvailable() ==
mPacketizerInput->mPacketSize);
MOZ_ASSERT(mSegment.GetDuration() >= 1);
MOZ_ASSERT(mSegment.GetDuration() <= mPacketizerInput->mPacketSize);
}
void AudioInputProcessing::ProcessOutputData(AudioProcessingTrack* aTrack,
const AudioChunk& aChunk) {
MOZ_ASSERT(aChunk.ChannelCount() > 0);
aTrack->AssertOnGraphThread();
if (!mEnabled || IsPassThrough(aTrack->Graph())) {
return;
}
TrackRate sampleRate = aTrack->mSampleRate;
uint32_t framesPerPacket = GetPacketSize(sampleRate); // in frames
// Downmix from aChannels to MAX_CHANNELS if needed.
uint32_t channelCount =
std::min<uint32_t>(aChunk.ChannelCount(), MAX_CHANNELS);
if (channelCount != mOutputBufferChannelCount ||
channelCount * framesPerPacket != mOutputBuffer.Length()) {
mOutputBuffer.SetLength(channelCount * framesPerPacket);
mOutputBufferChannelCount = channelCount;
// It's ok to drop the audio still in the packetizer here: if this changes,
// we changed devices or something.
mOutputBufferFrameCount = 0;
}
TrackTime chunkOffset = 0;
AutoTArray<float*, MAX_CHANNELS> channelPtrs;
channelPtrs.SetLength(channelCount);
do {
MOZ_ASSERT(mOutputBufferFrameCount < framesPerPacket);
uint32_t packetRemainder = framesPerPacket - mOutputBufferFrameCount;
mSubChunk = aChunk;
mSubChunk.SliceTo(
chunkOffset, std::min(chunkOffset + packetRemainder, aChunk.mDuration));
MOZ_ASSERT(mSubChunk.mDuration <= packetRemainder);
for (uint32_t channel = 0; channel < channelCount; channel++) {
channelPtrs[channel] =
&mOutputBuffer[channel * framesPerPacket + mOutputBufferFrameCount];
}
mSubChunk.DownMixTo(channelPtrs);
chunkOffset += mSubChunk.mDuration;
MOZ_ASSERT(chunkOffset <= aChunk.mDuration);
mOutputBufferFrameCount += mSubChunk.mDuration;
MOZ_ASSERT(mOutputBufferFrameCount <= framesPerPacket);
if (mOutputBufferFrameCount == framesPerPacket) {
// Have a complete packet. Analyze it.
EnsureAudioProcessing(aTrack);
for (uint32_t channel = 0; channel < channelCount; channel++) {
channelPtrs[channel] = &mOutputBuffer[channel * framesPerPacket];
}
StreamConfig reverseConfig(sampleRate, channelCount);
DebugOnly<int> err = mAudioProcessing->AnalyzeReverseStream(
channelPtrs.Elements(), reverseConfig);
MOZ_ASSERT(!err, "Could not process the reverse stream.");
mOutputBufferFrameCount = 0;
}
} while (chunkOffset < aChunk.mDuration);
mSubChunk.SetNull(0);
}
// Only called if we're not in passthrough mode
void AudioInputProcessing::PacketizeAndProcess(AudioProcessingTrack* aTrack,
const AudioSegment& aSegment) {
MediaTrackGraph* graph = aTrack->Graph();
MOZ_ASSERT(!IsPassThrough(graph),
"This should be bypassed when in PassThrough mode.");
MOZ_ASSERT(mEnabled);
MOZ_ASSERT(mPacketizerInput);
MOZ_ASSERT(mPacketizerInput->mPacketSize ==
GetPacketSize(aTrack->mSampleRate));
// Calculate number of the pending frames in mChunksInPacketizer.
auto pendingFrames = [&]() {
TrackTime frames = 0;
for (const auto& p : mChunksInPacketizer) {
frames += p.first;
}
return frames;
};
// Precondition of the Principal-labelling logic below.
MOZ_ASSERT(mPacketizerInput->FramesAvailable() ==
static_cast<uint32_t>(pendingFrames()));
// The WriteToInterleavedBuffer will do upmix or downmix if the channel-count
// in aSegment's chunks is different from mPacketizerInput->mChannels
size_t sampleCount = aSegment.WriteToInterleavedBuffer(
mInterleavedBuffer, mPacketizerInput->mChannels);
size_t frameCount =
sampleCount / static_cast<size_t>(mPacketizerInput->mChannels);
// Packetize our input data into 10ms chunks, deinterleave into planar channel
// buffers, process, and append to the right MediaStreamTrack.
mPacketizerInput->Input(mInterleavedBuffer.Elements(),
static_cast<uint32_t>(frameCount));
// Update mChunksInPacketizer and make sure the precondition for the
// Principal-labelling logic still holds.
for (AudioSegment::ConstChunkIterator iter(aSegment); !iter.IsEnded();
iter.Next()) {
MOZ_ASSERT(iter->mDuration > 0);
mChunksInPacketizer.emplace_back(
std::make_pair(iter->mDuration, iter->mPrincipalHandle));
}
MOZ_ASSERT(mPacketizerInput->FramesAvailable() ==
static_cast<uint32_t>(pendingFrames()));
LOG_FRAME(
"(Graph %p, Driver %p) AudioInputProcessing %p Packetizing %zu frames. "
"Packetizer has %u frames (enough for %u packets) now",
graph, graph->CurrentDriver(), this, frameCount,
mPacketizerInput->FramesAvailable(),
mPacketizerInput->PacketsAvailable());
size_t offset = 0;
while (mPacketizerInput->PacketsAvailable()) {
mPacketCount++;
uint32_t samplesPerPacket =
mPacketizerInput->mPacketSize * mPacketizerInput->mChannels;
if (mInputBuffer.Length() < samplesPerPacket) {
mInputBuffer.SetLength(samplesPerPacket);
}
if (mDeinterleavedBuffer.Length() < samplesPerPacket) {
mDeinterleavedBuffer.SetLength(samplesPerPacket);
}
float* packet = mInputBuffer.Data();
mPacketizerInput->Output(packet);
// Downmix from mPacketizerInput->mChannels to mono if needed. We always
// have floats here, the packetizer performed the conversion.
AutoTArray<float*, 8> deinterleavedPacketizedInputDataChannelPointers;
uint32_t channelCountInput = 0;
if (mPacketizerInput->mChannels > MAX_CHANNELS) {
channelCountInput = MONO;
deinterleavedPacketizedInputDataChannelPointers.SetLength(
channelCountInput);
deinterleavedPacketizedInputDataChannelPointers[0] =
mDeinterleavedBuffer.Data();
// Downmix to mono (and effectively have a planar buffer) by summing all
// channels in the first channel, and scaling by the number of channels to
// avoid clipping.
float gain = 1.f / mPacketizerInput->mChannels;
size_t readIndex = 0;
for (size_t i = 0; i < mPacketizerInput->mPacketSize; i++) {
mDeinterleavedBuffer.Data()[i] = 0.;
for (size_t j = 0; j < mPacketizerInput->mChannels; j++) {
mDeinterleavedBuffer.Data()[i] += gain * packet[readIndex++];
}
}
} else {
channelCountInput = mPacketizerInput->mChannels;
// Deinterleave the input data
// Prepare an array pointing to deinterleaved channels.
deinterleavedPacketizedInputDataChannelPointers.SetLength(
channelCountInput);
offset = 0;
for (size_t i = 0;
i < deinterleavedPacketizedInputDataChannelPointers.Length(); ++i) {
deinterleavedPacketizedInputDataChannelPointers[i] =
mDeinterleavedBuffer.Data() + offset;
offset += mPacketizerInput->mPacketSize;
}
// Deinterleave to mInputBuffer, pointed to by inputBufferChannelPointers.
Deinterleave(packet, mPacketizerInput->mPacketSize, channelCountInput,
deinterleavedPacketizedInputDataChannelPointers.Elements());
}
StreamConfig inputConfig(aTrack->mSampleRate, channelCountInput);
StreamConfig outputConfig = inputConfig;
EnsureAudioProcessing(aTrack);
mAudioProcessing->set_stream_delay_ms(0);
CheckedInt<size_t> bufferSize(sizeof(float));
bufferSize *= mPacketizerInput->mPacketSize;
bufferSize *= channelCountInput;
RefPtr<SharedBuffer> buffer = SharedBuffer::Create(bufferSize);
// Prepare channel pointers to the SharedBuffer created above.
AutoTArray<float*, 8> processedOutputChannelPointers;
AutoTArray<const float*, 8> processedOutputChannelPointersConst;
processedOutputChannelPointers.SetLength(channelCountInput);
processedOutputChannelPointersConst.SetLength(channelCountInput);
offset = 0;
for (size_t i = 0; i < processedOutputChannelPointers.Length(); ++i) {
processedOutputChannelPointers[i] =
static_cast<float*>(buffer->Data()) + offset;
processedOutputChannelPointersConst[i] =
static_cast<float*>(buffer->Data()) + offset;
offset += mPacketizerInput->mPacketSize;
}
mAudioProcessing->ProcessStream(
deinterleavedPacketizedInputDataChannelPointers.Elements(), inputConfig,
outputConfig, processedOutputChannelPointers.Elements());
// If logging is enabled, dump the audio processing stats twice a second
if (MOZ_LOG_TEST(gMediaManagerLog, LogLevel::Debug) &&
!(mPacketCount % 50)) {
AudioProcessingStats stats = mAudioProcessing->GetStatistics();
char msg[1024];
size_t offset = 0;
#define AddIfValue(format, member) \
if (stats.member.has_value()) { \
offset += SprintfBuf(msg + offset, sizeof(msg) - offset, \
#member ":" format ", ", stats.member.value()); \
}
AddIfValue("%d", voice_detected);
AddIfValue("%lf", echo_return_loss);
AddIfValue("%lf", echo_return_loss_enhancement);
AddIfValue("%lf", divergent_filter_fraction);
AddIfValue("%d", delay_median_ms);
AddIfValue("%d", delay_standard_deviation_ms);
AddIfValue("%d", delay_ms);
#undef AddIfValue
LOG("AudioProcessing statistics: %s", msg);
}
if (mEnded) {
continue;
}
// We already have planar audio data of the right format. Insert into the
// MTG.
MOZ_ASSERT(processedOutputChannelPointers.Length() == channelCountInput);
// Insert the processed data chunk by chunk to mSegment with the paired
// PrincipalHandle value. The chunks are tracked in mChunksInPacketizer.
auto getAudioChunk = [&](TrackTime aStart, TrackTime aEnd,
const PrincipalHandle& aPrincipalHandle) {
if (aStart == aEnd) {
return AudioChunk();
}
RefPtr<SharedBuffer> other = buffer;
AudioChunk c =
AudioChunk(other.forget(), processedOutputChannelPointersConst,
static_cast<TrackTime>(mPacketizerInput->mPacketSize),
aPrincipalHandle);
c.SliceTo(aStart, aEnd);
return c;
};
// The number of frames of data that needs to be labelled with Principal
// values.
TrackTime len = static_cast<TrackTime>(mPacketizerInput->mPacketSize);
// The start offset of the unlabelled chunk.
TrackTime start = 0;
// By mChunksInPacketizer's information, we can keep labelling the
// unlabelled frames chunk by chunk.
while (!mChunksInPacketizer.empty()) {
auto& [frames, principal] = mChunksInPacketizer.front();
const TrackTime end = start + frames;
if (end > len) {
// If the left unlabelled frames are part of this chunk, then we need to
// adjust the number of frames in the chunk.
if (len > start) {
mSegment.AppendAndConsumeChunk(getAudioChunk(start, len, principal));
frames -= len - start;
}
break;
}
// Otherwise, the number of unlabelled frames is larger than or equal to
// this chunk. We can label the whole chunk directly.
mSegment.AppendAndConsumeChunk(getAudioChunk(start, end, principal));
start = end;
mChunksInPacketizer.pop_front();
}
LOG_FRAME(
"(Graph %p, Driver %p) AudioInputProcessing %p Appending %u frames of "
"packetized audio, leaving %u frames in packetizer (%" PRId64
" frames in mChunksInPacketizer)",
graph, graph->CurrentDriver(), this, mPacketizerInput->mPacketSize,
mPacketizerInput->FramesAvailable(), pendingFrames());
// Postcondition of the Principal-labelling logic.
MOZ_ASSERT(mPacketizerInput->FramesAvailable() ==
static_cast<uint32_t>(pendingFrames()));
}
}
void AudioInputProcessing::DeviceChanged(MediaTrackGraph* aGraph) {
aGraph->AssertOnGraphThread();
// Reset some processing
if (mAudioProcessing) {
mAudioProcessing->Initialize();
}
LOG_FRAME(
"(Graph %p, Driver %p) AudioInputProcessing %p Reinitializing audio "
"processing",
aGraph, aGraph->CurrentDriver(), this);
}
void AudioInputProcessing::ApplySettings(MediaTrackGraph* aGraph,
CubebUtils::AudioDeviceID aDeviceID,
const MediaEnginePrefs& aSettings) {
TRACE("AudioInputProcessing::ApplySettings");
aGraph->AssertOnGraphThread();
// Read previous state from mSettings.
uint32_t oldChannelCount = GetRequestedInputChannelCount();
bool wasPassThrough = IsPassThrough(aGraph);
mSettings = aSettings;
if (mAudioProcessing) {
mAudioProcessing->ApplyConfig(ConfigForPrefs(aSettings));
}
if (oldChannelCount != GetRequestedInputChannelCount()) {
RequestedInputChannelCountChanged(aGraph, aDeviceID);
}
if (wasPassThrough != IsPassThrough(aGraph)) {
PassThroughChanged(aGraph);
}
}
void AudioInputProcessing::End() {
mEnded = true;
mSegment.Clear();
}
TrackTime AudioInputProcessing::NumBufferedFrames(
MediaTrackGraph* aGraph) const {
aGraph->AssertOnGraphThread();
return mSegment.GetDuration();
}
void AudioInputProcessing::EnsurePacketizer(AudioProcessingTrack* aTrack) {
aTrack->AssertOnGraphThread();
MOZ_ASSERT(mEnabled);
MediaTrackGraph* graph = aTrack->Graph();
MOZ_ASSERT(!IsPassThrough(graph));
uint32_t channelCount = GetRequestedInputChannelCount();
MOZ_ASSERT(channelCount > 0);
if (mPacketizerInput && mPacketizerInput->mChannels == channelCount) {
return;
}
// If mPacketizerInput exists but with different channel-count, there is no
// need to change pre-buffering since the packet size is the same as the old
// one, since the rate is a constant.
MOZ_ASSERT_IF(mPacketizerInput, mPacketizerInput->mPacketSize ==
GetPacketSize(aTrack->mSampleRate));
bool needPreBuffering = !mPacketizerInput;
if (mPacketizerInput) {
const TrackTime numBufferedFrames =
static_cast<TrackTime>(mPacketizerInput->FramesAvailable());
mSegment.AppendNullData(numBufferedFrames);
mPacketizerInput = Nothing();
mChunksInPacketizer.clear();
}
mPacketizerInput.emplace(GetPacketSize(aTrack->mSampleRate), channelCount);
if (needPreBuffering) {
LOG_FRAME(
"(Graph %p, Driver %p) AudioInputProcessing %p: Adding %u frames of "
"silence as pre-buffering",
graph, graph->CurrentDriver(), this, mPacketizerInput->mPacketSize);
AudioSegment buffering;
buffering.AppendNullData(
static_cast<TrackTime>(mPacketizerInput->mPacketSize));
PacketizeAndProcess(aTrack, buffering);
}
}
void AudioInputProcessing::EnsureAudioProcessing(AudioProcessingTrack* aTrack) {
aTrack->AssertOnGraphThread();
MediaTrackGraph* graph = aTrack->Graph();
// If the AEC might need to deal with drift then inform it of this and it
// will be less conservative about echo suppression. This can lead to some
// suppression of non-echo signal, so do this only when drift is expected.
bool haveAECAndDrift = mSettings.mAecOn;
if (haveAECAndDrift) {
if (mSettings.mExpectDrift < 0) {
haveAECAndDrift =
graph->OutputForAECMightDrift() ||
aTrack->GetDeviceInputTrackGraphThread()->AsNonNativeInputTrack();
} else {
haveAECAndDrift = mSettings.mExpectDrift > 0;
}
}
if (!mAudioProcessing || haveAECAndDrift != mHadAECAndDrift) {
TRACE("AudioProcessing creation");
LOG("Track %p AudioInputProcessing %p creating AudioProcessing. "
"aec+drift: %s",
aTrack, this, haveAECAndDrift ? "Y" : "N");
mHadAECAndDrift = haveAECAndDrift;
AudioProcessingBuilder builder;
builder.SetConfig(ConfigForPrefs(mSettings));
if (haveAECAndDrift) {
// Setting an EchoControlFactory always enables AEC, overriding
// Config::echo_canceller.enabled, so do this only when AEC is enabled.
EchoCanceller3Config aec3Config;
aec3Config.echo_removal_control.has_clock_drift = true;
builder.SetEchoControlFactory(
std::make_unique<EchoCanceller3Factory>(aec3Config));
}
mAudioProcessing.reset(builder.Create().release());
}
}
void AudioInputProcessing::ResetAudioProcessing(MediaTrackGraph* aGraph) {
aGraph->AssertOnGraphThread();
MOZ_ASSERT(IsPassThrough(aGraph) || !mEnabled);
MOZ_ASSERT(mPacketizerInput);
LOG_FRAME(
"(Graph %p, Driver %p) AudioInputProcessing %p Resetting audio "
"processing",
aGraph, aGraph->CurrentDriver(), this);
// Reset AudioProcessing so that if we resume processing in the future it
// doesn't depend on old state.
if (mAudioProcessing) {
mAudioProcessing->Initialize();
}
MOZ_ASSERT(static_cast<uint32_t>(mSegment.GetDuration()) +
mPacketizerInput->FramesAvailable() ==
mPacketizerInput->mPacketSize);
// It's ok to clear all the internal buffer here since we won't use mSegment
// in pass-through mode or when audio processing is disabled.
LOG_FRAME(
"(Graph %p, Driver %p) AudioInputProcessing %p Emptying out %" PRId64
" frames of data",
aGraph, aGraph->CurrentDriver(), this, mSegment.GetDuration());
mSegment.Clear();
mPacketizerInput = Nothing();
mChunksInPacketizer.clear();
}
void AudioProcessingTrack::Destroy() {
MOZ_ASSERT(NS_IsMainThread());
DisconnectDeviceInput();
MediaTrack::Destroy();
}
void AudioProcessingTrack::SetInputProcessing(
RefPtr<AudioInputProcessing> aInputProcessing) {
if (IsDestroyed()) {
return;
}
QueueControlMessageWithNoShutdown(
[self = RefPtr{this}, this,
inputProcessing = std::move(aInputProcessing)]() mutable {
TRACE("AudioProcessingTrack::SetInputProcessingImpl");
SetInputProcessingImpl(std::move(inputProcessing));
});
}
AudioProcessingTrack* AudioProcessingTrack::Create(MediaTrackGraph* aGraph) {
MOZ_ASSERT(NS_IsMainThread());
AudioProcessingTrack* track = new AudioProcessingTrack(aGraph->GraphRate());
aGraph->AddTrack(track);
return track;
}
void AudioProcessingTrack::DestroyImpl() {
ProcessedMediaTrack::DestroyImpl();
if (mInputProcessing) {
mInputProcessing->End();
}
}
void AudioProcessingTrack::ProcessInput(GraphTime aFrom, GraphTime aTo,
uint32_t aFlags) {
TRACE_COMMENT("AudioProcessingTrack::ProcessInput", "AudioProcessingTrack %p",
this);
MOZ_ASSERT(mInputProcessing);
LOG_FRAME(
"(Graph %p, Driver %p) AudioProcessingTrack %p ProcessInput from %" PRId64
" to %" PRId64 ", needs %" PRId64 " frames",
mGraph, mGraph->CurrentDriver(), this, aFrom, aTo, aTo - aFrom);
if (aFrom >= aTo) {
return;
}
if (!mInputProcessing->IsEnded()) {
MOZ_ASSERT(TrackTimeToGraphTime(GetEnd()) == aFrom);
if (mInputs.IsEmpty()) {
GetData<AudioSegment>()->AppendNullData(aTo - aFrom);
LOG_FRAME("(Graph %p, Driver %p) AudioProcessingTrack %p Filling %" PRId64
" frames of null data (no input source)",
mGraph, mGraph->CurrentDriver(), this, aTo - aFrom);
} else {
MOZ_ASSERT(mInputs.Length() == 1);
AudioSegment data;
DeviceInputConsumerTrack::GetInputSourceData(data, aFrom, aTo);
mInputProcessing->Process(this, aFrom, aTo, &data,
GetData<AudioSegment>());
}
MOZ_ASSERT(TrackTimeToGraphTime(GetEnd()) == aTo);
ApplyTrackDisabling(mSegment.get());
} else if (aFlags & ALLOW_END) {
mEnded = true;
}
}
void AudioProcessingTrack::NotifyOutputData(MediaTrackGraph* aGraph,
const AudioChunk& aChunk) {
MOZ_ASSERT(mGraph == aGraph, "Cannot feed audio output to another graph");
AssertOnGraphThread();
if (mInputProcessing) {
mInputProcessing->ProcessOutputData(this, aChunk);
}
}
void AudioProcessingTrack::SetInputProcessingImpl(
RefPtr<AudioInputProcessing> aInputProcessing) {
AssertOnGraphThread();
mInputProcessing = std::move(aInputProcessing);
}
MediaEngineWebRTCAudioCaptureSource::MediaEngineWebRTCAudioCaptureSource(
const MediaDevice* aMediaDevice) {
MOZ_ASSERT(aMediaDevice->mMediaSource == MediaSourceEnum::AudioCapture);
}
/* static */
nsString MediaEngineWebRTCAudioCaptureSource::GetUUID() {
nsID uuid{};
char uuidBuffer[NSID_LENGTH];
nsCString asciiString;
ErrorResult rv;
rv = nsID::GenerateUUIDInPlace(uuid);
if (rv.Failed()) {
return u""_ns;
}
uuid.ToProvidedString(uuidBuffer);
asciiString.AssignASCII(uuidBuffer);
// Remove {} and the null terminator
return NS_ConvertASCIItoUTF16(Substring(asciiString, 1, NSID_LENGTH - 3));
}
/* static */
nsString MediaEngineWebRTCAudioCaptureSource::GetGroupId() {
return u"AudioCaptureGroup"_ns;
}
void MediaEngineWebRTCAudioCaptureSource::SetTrack(
const RefPtr<MediaTrack>& aTrack, const PrincipalHandle& aPrincipalHandle) {
AssertIsOnOwningThread();
// Nothing to do here. aTrack is a placeholder dummy and not exposed.
}
nsresult MediaEngineWebRTCAudioCaptureSource::Start() {
AssertIsOnOwningThread();
return NS_OK;
}
nsresult MediaEngineWebRTCAudioCaptureSource::Stop() {
AssertIsOnOwningThread();
return NS_OK;
}
nsresult MediaEngineWebRTCAudioCaptureSource::Reconfigure(
const dom::MediaTrackConstraints& aConstraints,
const MediaEnginePrefs& aPrefs, const char** aOutBadConstraint) {
return NS_OK;
}
void MediaEngineWebRTCAudioCaptureSource::GetSettings(
dom::MediaTrackSettings& aOutSettings) const {
aOutSettings.mAutoGainControl.Construct(false);
aOutSettings.mEchoCancellation.Construct(false);
aOutSettings.mNoiseSuppression.Construct(false);
aOutSettings.mChannelCount.Construct(1);
}
} // namespace mozilla
// Don't allow our macros to leak into other cpps in our unified build unit.
#undef MAX_CHANNELS
#undef MONO
#undef MAX_SAMPLING_FREQ