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ExampleAVAudioEngineDevice.m
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ExampleAVAudioEngineDevice.m
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//
// ExampleAVAudioEngineDevice.m
// AudioDeviceExample
//
// Copyright © 2018-2019 Twilio, Inc. All rights reserved.
//
#import "ExampleAVAudioEngineDevice.h"
// We want to get as close to 10 msec buffers as possible because this is what the media engine prefers.
static double const kPreferredIOBufferDurationSec = 0.01;
// We will use mono playback and recording where available.
static size_t const kPreferredNumberOfChannels = 1;
// An audio sample is a signed 16-bit integer.
static size_t const kAudioSampleSize = 2;
static uint32_t const kPreferredSampleRate = 48000;
/*
* Calls to AudioUnitInitialize() can fail if called back-to-back after a format change or adding and removing tracks.
* A fall-back solution is to allow multiple sequential calls with a small delay between each. This factor sets the max
* number of allowed initialization attempts.
*/
static const int kMaxNumberOfAudioUnitInitializeAttempts = 5;
/*
* Calls to AudioOutputUnitStart() can fail if called during CallKit performSetHeldAction (as a workaround for Apple's own bugs when the remote caller ends a call that interrupted our own)
* Repeated attempts to call this function will allow time for the call to actually be unheld by CallKit thereby allowing us to start our AudioUnit
*/
static const int kMaxNumberOfAudioUnitStartAttempts = 5;
/*
* Calls to setupAVAudioSession can fail if called during CallKit performSetHeldAction (as a workaround for Apple's own bugs when the remote caller ends a call that interrupted our own)
* Repeated attempts to call this function will allow time for the call to actually be unheld by CallKit thereby allowing us to activate the AVAudioSession
*/
static const int kMaxNumberOfSetupAVAudioSessionAttempts = 5;
// Audio renderer contexts used in core audio's playout callback to retrieve the sdk's audio device context.
typedef struct AudioRendererContext {
// Audio device context received in AudioDevice's `startRendering:context` callback.
TVIAudioDeviceContext deviceContext;
// Maximum frames per buffer.
size_t maxFramesPerBuffer;
// Buffer passed to AVAudioEngine's manualRenderingBlock to receive the mixed audio data.
AudioBufferList *bufferList;
/*
* Points to AVAudioEngine's manualRenderingBlock. This block is called from within the VoiceProcessingIO playout
* callback in order to receive mixed audio data from AVAudioEngine in real time.
*/
void *renderBlock;
} AudioRendererContext;
// Audio renderer contexts used in core audio's record callback to retrieve the sdk's audio device context.
typedef struct AudioCapturerContext {
// Audio device context received in AudioDevice's `startCapturing:context` callback.
TVIAudioDeviceContext deviceContext;
// Preallocated buffer list. Please note the buffer itself will be provided by Core Audio's VoiceProcessingIO audio unit.
AudioBufferList *bufferList;
// Preallocated mixed (AudioUnit mic + AVAudioPlayerNode file) audio buffer list.
AudioBufferList *mixedAudioBufferList;
// Core Audio's VoiceProcessingIO audio unit.
AudioUnit audioUnit;
/*
* Points to AVAudioEngine's manualRenderingBlock. This block is called from within the VoiceProcessingIO playout
* callback in order to receive mixed audio data from AVAudioEngine in real time.
*/
void *renderBlock;
} AudioCapturerContext;
// The VoiceProcessingIO audio unit uses bus 0 for ouptut, and bus 1 for input.
static int kOutputBus = 0;
static int kInputBus = 1;
// This is the maximum slice size for VoiceProcessingIO (as observed in the field). We will double check at initialization time.
static size_t kMaximumFramesPerBuffer = 3072;
@interface ExampleAVAudioEngineDevice()
@property (nonatomic, assign, getter=isInterrupted) BOOL interrupted;
@property (nonatomic, assign) AudioUnit audioUnit;
@property (nonatomic, assign) AudioBufferList captureBufferList;
@property (nonatomic, strong, nullable) TVIAudioFormat *renderingFormat;
@property (nonatomic, strong, nullable) TVIAudioFormat *capturingFormat;
@property (atomic, assign) AudioRendererContext *renderingContext;
@property (nonatomic, assign) AudioCapturerContext *capturingContext;
// AudioEngine properties
@property (nonatomic, strong) AVAudioEngine *playoutEngine;
@property (nonatomic, strong) AVAudioPlayerNode *playoutFilePlayer;
@property (nonatomic, strong) AVAudioUnitReverb *playoutReverb;
@property (nonatomic, strong) AVAudioEngine *recordEngine;
@property (nonatomic, strong) AVAudioPlayerNode *recordFilePlayer;
@property (nonatomic, strong) AVAudioUnitReverb *recordReverb;
@property (nonatomic, strong) AVAudioPCMBuffer *musicBuffer;
@property (atomic, assign) BOOL continuousMusic;
@end
@implementation ExampleAVAudioEngineDevice
#pragma mark - Init & Dealloc
- (id)init {
self = [super init];
if (self) {
/*
* Initialize rendering and capturing context. The deviceContext will be be filled in when startRendering or
* startCapturing gets called.
*/
_enabled = true;
// Initialize the rendering context
self.renderingContext = malloc(sizeof(AudioRendererContext));
memset(self.renderingContext, 0, sizeof(AudioRendererContext));
// Setup the AVAudioEngine along with the rendering context
if (![self setupPlayoutAudioEngine]) {
NSLog(@"Failed to setup AVAudioEngine");
}
// Initialize the capturing context
self.capturingContext = malloc(sizeof(AudioCapturerContext));
memset(self.capturingContext, 0, sizeof(AudioCapturerContext));
self.capturingContext->bufferList = &_captureBufferList;
// Setup the AVAudioEngine along with the rendering context
if (![self setupRecordAudioEngine]) {
NSLog(@"Failed to setup AVAudioEngine");
}
[self setupAVAudioSession];
[self registerAVAudioSessionObservers];
}
return self;
}
- (void)dealloc {
[self unregisterAVAudioSessionObservers];
[self teardownAudioEngine];
free(self.renderingContext);
self.renderingContext = NULL;
AudioBufferList *mixedAudioBufferList = self.capturingContext->mixedAudioBufferList;
if (mixedAudioBufferList) {
for (size_t i = 0; i < mixedAudioBufferList->mNumberBuffers; i++) {
free(mixedAudioBufferList->mBuffers[i].mData);
}
free(mixedAudioBufferList);
}
free(self.capturingContext);
self.capturingContext = NULL;
}
+ (NSString *)description {
return @"AVAudioEngine Audio Mixing";
}
/*
* Determine at runtime the maximum slice size used by VoiceProcessingIO. Setting the stream format and sample rate
* doesn't appear to impact the maximum size so we prefer to read this value once at initialization time.
*/
+ (void)initialize {
AudioComponentDescription audioUnitDescription = [self audioUnitDescription];
AudioComponent audioComponent = AudioComponentFindNext(NULL, &audioUnitDescription);
AudioUnit audioUnit;
OSStatus status = AudioComponentInstanceNew(audioComponent, &audioUnit);
if (status != 0) {
NSLog(@"Could not find VoiceProcessingIO AudioComponent instance!");
return;
}
UInt32 framesPerSlice = 0;
UInt32 propertySize = sizeof(framesPerSlice);
status = AudioUnitGetProperty(audioUnit, kAudioUnitProperty_MaximumFramesPerSlice,
kAudioUnitScope_Global, kOutputBus,
&framesPerSlice, &propertySize);
if (status != 0) {
NSLog(@"Could not read VoiceProcessingIO AudioComponent instance!");
AudioComponentInstanceDispose(audioUnit);
return;
}
if (framesPerSlice < kMaximumFramesPerBuffer) {
framesPerSlice = (UInt32) kMaximumFramesPerBuffer;
status = AudioUnitSetProperty(audioUnit, kAudioUnitProperty_MaximumFramesPerSlice,
kAudioUnitScope_Global, kOutputBus,
&framesPerSlice, sizeof(framesPerSlice));
} else {
kMaximumFramesPerBuffer = (size_t)framesPerSlice;
}
NSLog(@"This device uses a maximum slice size of %d frames.", (unsigned int)framesPerSlice);
AudioComponentInstanceDispose(audioUnit);
}
#pragma mark - Public
- (void)setEnabled:(BOOL)enabled {
@synchronized(self) {
TVIAudioDeviceContext context = [self deviceContext];
if (context) {
TVIAudioDeviceExecuteWorkerBlock(context, ^{
@synchronized(self) {
// Disabling audio
if (!enabled && self.enabled) {
NSLog(@"ExampleAVAudioEngineDevice disabling");
[self stopAndTeardownAudioUnit];
}
// Enabling audio
if (enabled && !self.enabled) {
NSLog(@"ExampleAVAudioEngineDevice reenabling");
[self reinitialize];
}
self->_enabled = enabled;
}
});
}
else {
NSLog(@"ExampleAVAudioEngineDevice has no device context. Setting enabled to %@", enabled ? @"YES" : @"NO");
_enabled = enabled;
}
}
}
#pragma mark - Private (AVAudioEngine)
- (BOOL)setupAudioEngine {
return [self setupPlayoutAudioEngine] && [self setupRecordAudioEngine];
}
- (BOOL)setupRecordAudioEngine {
NSAssert(_recordEngine == nil, @"AVAudioEngine is already configured");
/*
* By default AVAudioEngine will render to/from the audio device, and automatically establish connections between
* nodes, e.g. inputNode -> effectNode -> outputNode.
*/
_recordEngine = [AVAudioEngine new];
// AVAudioEngine operates on the same format as the Core Audio output bus.
NSError *error = nil;
const AudioStreamBasicDescription asbd = [[[self class] activeFormat] streamDescription];
AVAudioFormat *format = [[AVAudioFormat alloc] initWithStreamDescription:&asbd];
// Switch to manual rendering mode
[_recordEngine stop];
BOOL success = [_recordEngine enableManualRenderingMode:AVAudioEngineManualRenderingModeRealtime
format:format
maximumFrameCount:(uint32_t)kMaximumFramesPerBuffer
error:&error];
if (!success) {
NSLog(@"Failed to setup manual rendering mode, error = %@", error);
return NO;
}
/*
* In manual rendering mode, AVAudioEngine won't receive audio from the microhpone. Instead, it will receive the
* audio data from the Video SDK and mix it in MainMixerNode. Here we connect the input node to the main mixer node.
* InputNode -> MainMixer -> OutputNode
*/
[_recordEngine connect:_recordEngine.inputNode to:_recordEngine.mainMixerNode format:format];
/*
* Attach AVAudioPlayerNode node to play music from a file.
* AVAudioPlayerNode -> ReverbNode -> MainMixer -> OutputNode (note: ReverbNode is optional)
*/
[self attachMusicNodeToEngine:_recordEngine];
// Set the block to provide input data to engine
AVAudioInputNode *inputNode = _recordEngine.inputNode;
AudioBufferList *captureBufferList = &_captureBufferList;
success = [inputNode setManualRenderingInputPCMFormat:format
inputBlock: ^const AudioBufferList * _Nullable(AVAudioFrameCount inNumberOfFrames) {
assert(inNumberOfFrames <= kMaximumFramesPerBuffer);
return captureBufferList;
}];
if (!success) {
NSLog(@"Failed to set the manual rendering block");
return NO;
}
// The manual rendering block (called in Core Audio's VoiceProcessingIO's playout callback at real time)
self.capturingContext->renderBlock = (__bridge void *)(_recordEngine.manualRenderingBlock);
success = [_recordEngine startAndReturnError:&error];
if (!success) {
NSLog(@"Failed to start AVAudioEngine, error = %@", error);
return NO;
}
return YES;
}
- (BOOL)setupPlayoutAudioEngine {
NSAssert(_playoutEngine == nil, @"AVAudioEngine is already configured");
/*
* By default AVAudioEngine will render to/from the audio device, and automatically establish connections between
* nodes, e.g. inputNode -> effectNode -> outputNode.
*/
_playoutEngine = [AVAudioEngine new];
// AVAudioEngine operates on the same format as the Core Audio output bus.
NSError *error = nil;
const AudioStreamBasicDescription asbd = [[[self class] activeFormat] streamDescription];
AVAudioFormat *format = [[AVAudioFormat alloc] initWithStreamDescription:&asbd];
// Switch to manual rendering mode
[_playoutEngine stop];
BOOL success = [_playoutEngine enableManualRenderingMode:AVAudioEngineManualRenderingModeRealtime
format:format
maximumFrameCount:(uint32_t)kMaximumFramesPerBuffer
error:&error];
if (!success) {
NSLog(@"Failed to setup manual rendering mode, error = %@", error);
return NO;
}
/*
* In manual rendering mode, AVAudioEngine won't receive audio from the microhpone. Instead, it will receive the
* audio data from the Video SDK and mix it in MainMixerNode. Here we connect the input node to the main mixer node.
* InputNode -> MainMixer -> OutputNode
*/
[_playoutEngine connect:_playoutEngine.inputNode to:_playoutEngine.mainMixerNode format:format];
/*
* Attach AVAudioPlayerNode node to play music from a file.
* AVAudioPlayerNode -> ReverbNode -> MainMixer -> OutputNode (note: ReverbNode is optional)
*/
[self attachMusicNodeToEngine:_playoutEngine];
// Set the block to provide input data to engine
AudioRendererContext *context = _renderingContext;
AVAudioInputNode *inputNode = _playoutEngine.inputNode;
success = [inputNode setManualRenderingInputPCMFormat:format
inputBlock: ^const AudioBufferList * _Nullable(AVAudioFrameCount inNumberOfFrames) {
assert(inNumberOfFrames <= kMaximumFramesPerBuffer);
AudioBufferList *bufferList = context->bufferList;
int8_t *audioBuffer = (int8_t *)bufferList->mBuffers[0].mData;
UInt32 audioBufferSizeInBytes = bufferList->mBuffers[0].mDataByteSize;
if (context->deviceContext) {
/*
* Pull decoded, mixed audio data from the media engine into the
* AudioUnit's AudioBufferList.
*/
TVIAudioDeviceReadRenderData(context->deviceContext, audioBuffer, audioBufferSizeInBytes);
} else {
/*
* Return silence when we do not have the playout device context. This is the
* case when the remote participant has not published an audio track yet.
* Since the audio graph and audio engine has been setup, we can still play
* the music file using AVAudioEngine.
*/
memset(audioBuffer, 0, audioBufferSizeInBytes);
}
return bufferList;
}];
if (!success) {
NSLog(@"Failed to set the manual rendering block");
return NO;
}
// The manual rendering block (called in Core Audio's VoiceProcessingIO's playout callback at real time)
self.renderingContext->renderBlock = (__bridge void *)(_playoutEngine.manualRenderingBlock);
success = [_playoutEngine startAndReturnError:&error];
if (!success) {
NSLog(@"Failed to start AVAudioEngine, error = %@", error);
return NO;
}
return YES;
}
- (void)teardownRecordAudioEngine {
[_recordEngine stop];
_recordEngine = nil;
}
- (void)teardownPlayoutAudioEngine {
[_playoutEngine stop];
_playoutEngine = nil;
}
- (void)teardownAudioEngine {
[self teardownFilePlayers];
[self teardownPlayoutAudioEngine];
[self teardownRecordAudioEngine];
}
- (AVAudioPCMBuffer *)musicBuffer {
if (!_musicBuffer) {
NSString *fileName = [NSString stringWithFormat:@"%@/%@", [[NSBundle mainBundle] bundlePath], @"mixLoop.caf"];
NSURL *url = [NSURL fileURLWithPath:fileName];
AVAudioFile *file = [[AVAudioFile alloc] initForReading:url error:nil];
_musicBuffer = [[AVAudioPCMBuffer alloc] initWithPCMFormat:file.processingFormat
frameCapacity:(AVAudioFrameCount)file.length];
NSError *error = nil;
/*
* The sample app plays a small in size file `mixLoop.caf`, but if you are playing a bigger file, to unblock the
* calling (main) thread, you should execute `[file readIntoBuffer:buffer error:&error]` on a background thread,
* and once the read is completed, schedule buffer playout from the calling (main) thread.
*/
BOOL success = [file readIntoBuffer:_musicBuffer error:&error];
if (!success) {
NSLog(@"Failed to read audio file into buffer. error = %@", error);
_musicBuffer = nil;
}
}
return _musicBuffer;
}
- (void)scheduleMusicOnRecordEngine {
[self.recordFilePlayer scheduleBuffer:self.musicBuffer
atTime:nil
options:AVAudioPlayerNodeBufferInterrupts
completionHandler:^{
NSLog(@"Downstream file player finished buffer playing");
dispatch_async(dispatch_get_main_queue(), ^{
// Completed playing file via AVAudioEngine.
// `nil` context indicates TwilioVideo SDK does not need core audio either.
if (![self deviceContext]) {
[self tearDownAudio];
}
});
}];
[self.recordFilePlayer play];
/*
* TODO: The upstream AVAudioPlayerNode and downstream AVAudioPlayerNode schedule playout of the buffer
* "now". In order to ensure full synchronization, choose a time in the near future when scheduling playback.
*/
}
- (void)scheduleMusicOnPlayoutEngine {
[self.playoutFilePlayer scheduleBuffer:self.musicBuffer
atTime:nil
options:AVAudioPlayerNodeBufferInterrupts
completionHandler:^{
NSLog(@"Upstream file player finished buffer playing");
dispatch_async(dispatch_get_main_queue(), ^{
// Completed playing file via AVAudioEngine.
// `nil` context indicates TwilioVideo SDK does not need core audio either.
if (![self deviceContext]) {
[self tearDownAudio];
}
});
}];
[self.playoutFilePlayer play];
/*
* TODO: The upstream AVAudioPlayerNode and downstream AVAudioPlayerNode schedule playout of the buffer
* "now". In order to ensure full synchronization, choose a time in the near future when scheduling playback.
*/
}
- (void)playMusic:(BOOL)continuous {
@synchronized(self) {
if (continuous) {
if (!self.renderingFormat) {
self.renderingFormat = [self renderFormat];
}
if (!self.capturingFormat) {
self.capturingFormat = [self captureFormat];
}
// If device context is null, we will setup the audio unit by invoking the
// rendring and capturing.
[self initializeCapturer];
[self initializeRenderer];
[self startRendering:self.renderingContext->deviceContext];
[self startCapturing:self.capturingContext->deviceContext];
}
self.continuousMusic = continuous;
}
dispatch_async(dispatch_get_main_queue(), ^{
[self scheduleMusicOnPlayoutEngine];
[self scheduleMusicOnRecordEngine];
});
}
- (void)tearDownAudio {
@synchronized(self) {
[self teardownAudioUnit];
[self teardownAudioEngine];
self.continuousMusic = NO;
}
}
- (void)attachMusicNodeToEngine:(AVAudioEngine *)engine {
if (!engine) {
NSLog(@"Cannot play music. AudioEngine has not been created yet.");
return;
}
AVAudioPlayerNode *player = nil;
AVAudioUnitReverb *reverb = nil;
BOOL isPlayoutEngine = [self.playoutEngine isEqual:engine];
/*
* Attach an AVAudioPlayerNode as an input to the main mixer.
* AVAudioPlayerNode -> AVAudioUnitReverb -> MainMixerNode -> Core Audio
*/
NSString *fileName = [NSString stringWithFormat:@"%@/%@", [[NSBundle mainBundle] bundlePath], @"mixLoop.caf"];
NSURL *url = [NSURL fileURLWithPath:fileName];
AVAudioFile *file = [[AVAudioFile alloc] initForReading:url error:nil];
player = [[AVAudioPlayerNode alloc] init];
reverb = [[AVAudioUnitReverb alloc] init];
[reverb loadFactoryPreset:AVAudioUnitReverbPresetMediumHall];
reverb.wetDryMix = 50;
[engine attachNode:player];
[engine attachNode:reverb];
[engine connect:player to:reverb format:file.processingFormat];
[engine connect:reverb to:engine.mainMixerNode format:file.processingFormat];
if (isPlayoutEngine) {
self.playoutReverb = reverb;
self.playoutFilePlayer = player;
} else {
self.recordReverb = reverb;
self.recordFilePlayer = player;
}
}
- (void)teardownRecordFilePlayer {
if (self.recordFilePlayer) {
if (self.recordFilePlayer.isPlaying) {
[self.recordFilePlayer stop];
}
[self.recordEngine detachNode:self.recordFilePlayer];
[self.recordEngine detachNode:self.recordReverb];
self.recordReverb = nil;
}
}
- (void)teardownPlayoutFilePlayer {
if (self.playoutFilePlayer) {
if (self.playoutFilePlayer.isPlaying) {
[self.playoutFilePlayer stop];
}
[self.playoutEngine detachNode:self.playoutFilePlayer];
[self.playoutEngine detachNode:self.playoutReverb];
self.playoutReverb = nil;
}
}
- (void)teardownFilePlayers {
[self teardownRecordFilePlayer];
[self teardownPlayoutFilePlayer];
}
#pragma mark - TVIAudioDeviceRenderer
- (nullable TVIAudioFormat *)renderFormat {
if (!_renderingFormat) {
/*
* Assume that the AVAudioSession has already been configured and started and that the values
* for sampleRate and IOBufferDuration are final.
*/
_renderingFormat = [[self class] activeFormat];
self.renderingContext->maxFramesPerBuffer = _renderingFormat.framesPerBuffer;
}
return _renderingFormat;
}
- (BOOL)initializeRenderer {
/*
* In this example we don't need any fixed size buffers or other pre-allocated resources. We will simply write
* directly to the AudioBufferList provided in the AudioUnit's rendering callback.
*/
return YES;
}
- (BOOL)startRendering:(nonnull TVIAudioDeviceContext)context {
@synchronized(self) {
/*
* In this example, the app always publishes an audio track. So we will start the audio unit from the capturer
* call backs. We will restart the audio unit if a remote participant adds an audio track after the audio graph is
* established. Also we will re-establish the audio graph in case the format changes.
*/
if (_enabled) {
[self stopAndTeardownAudioUnit];
}
// If music is being played then we have already setup the engine
if (!self.continuousMusic) {
// We will make sure AVAudioEngine and AVAudioPlayerNode is accessed on the main queue.
dispatch_async(dispatch_get_main_queue(), ^{
AVAudioFormat *manualRenderingFormat = self.playoutEngine.manualRenderingFormat;
TVIAudioFormat *engineFormat = [[TVIAudioFormat alloc] initWithChannels:manualRenderingFormat.channelCount
sampleRate:manualRenderingFormat.sampleRate
framesPerBuffer:kMaximumFramesPerBuffer];
if ([engineFormat isEqual:[[self class] activeFormat]]) {
if (self.playoutEngine.isRunning) {
[self.playoutEngine stop];
}
NSError *error = nil;
if (![self.playoutEngine startAndReturnError:&error]) {
NSLog(@"Failed to start AVAudioEngine, error = %@", error);
}
} else {
[self teardownPlayoutFilePlayer];
[self teardownPlayoutAudioEngine];
[self setupPlayoutAudioEngine];
}
});
}
self.renderingContext->deviceContext = context;
if (_enabled) {
[self setupAndStartAudioUnit];
} else {
NSLog(@"ExampleAVAudioEngineDevice will NOT setup/start AudioUnit because it is currently disabled");
}
return YES;
}
}
- (BOOL)stopRendering {
@synchronized(self) {
// Continue playing music even after disconnected from a Room.
if (self.continuousMusic) {
return YES;
}
// If the capturer is runnning, we will not stop the audio unit.
if (!self.capturingContext->deviceContext && _enabled) {
[self stopAndTeardownAudioUnit];
}
self.renderingContext->deviceContext = NULL;
// We will make sure AVAudioEngine and AVAudioPlayerNode is accessed on the main queue.
dispatch_async(dispatch_get_main_queue(), ^{
if (self.playoutFilePlayer.isPlaying) {
[self.playoutFilePlayer stop];
}
if (self.playoutEngine.isRunning) {
[self.playoutEngine stop];
}
});
}
return YES;
}
#pragma mark - TVIAudioDeviceCapturer
- (nullable TVIAudioFormat *)captureFormat {
if (!_capturingFormat) {
/*
* Assume that the AVAudioSession has already been configured and started and that the values
* for sampleRate and IOBufferDuration are final.
*/
_capturingFormat = [[self class] activeFormat];
}
return _capturingFormat;
}
- (BOOL)initializeCapturer {
_captureBufferList.mNumberBuffers = 1;
_captureBufferList.mBuffers[0].mNumberChannels = kPreferredNumberOfChannels;
AudioBufferList *mixedAudioBufferList = self.capturingContext->mixedAudioBufferList;
if (mixedAudioBufferList == NULL) {
mixedAudioBufferList = (AudioBufferList*)malloc(sizeof(AudioBufferList));
mixedAudioBufferList->mNumberBuffers = 1;
mixedAudioBufferList->mBuffers[0].mNumberChannels = kPreferredNumberOfChannels;
mixedAudioBufferList->mBuffers[0].mDataByteSize = 0;
mixedAudioBufferList->mBuffers[0].mData = malloc(kMaximumFramesPerBuffer * kPreferredNumberOfChannels * kAudioSampleSize);
self.capturingContext->mixedAudioBufferList = mixedAudioBufferList;
}
return YES;
}
- (BOOL)startCapturing:(nonnull TVIAudioDeviceContext)context {
@synchronized (self) {
// Restart the audio unit if the audio graph is already set up and if we publish an audio track.
if (_enabled) {
[self stopAndTeardownAudioUnit];
}
// If music is being played then we have already setup the engine
if (!self.continuousMusic) {
// We will make sure AVAudioEngine and AVAudioPlayerNode is accessed on the main queue.
dispatch_async(dispatch_get_main_queue(), ^{
AVAudioFormat *manualRenderingFormat = self.recordEngine.manualRenderingFormat;
TVIAudioFormat *engineFormat = [[TVIAudioFormat alloc] initWithChannels:manualRenderingFormat.channelCount
sampleRate:manualRenderingFormat.sampleRate
framesPerBuffer:kMaximumFramesPerBuffer];
if ([engineFormat isEqual:[[self class] activeFormat]]) {
if (self.recordEngine.isRunning) {
[self.recordEngine stop];
}
NSError *error = nil;
if (![self.recordEngine startAndReturnError:&error]) {
NSLog(@"Failed to start AVAudioEngine, error = %@", error);
}
} else {
[self teardownRecordFilePlayer];
[self teardownRecordAudioEngine];
[self setupRecordAudioEngine];
}
});
}
self.capturingContext->deviceContext = context;
if (_enabled) {
[self setupAndStartAudioUnit];
} else {
NSLog(@"ExampleAVAudioEngineDevice will NOT setup/start AudioUnit because it is currently disabled");
}
return YES;
}
}
- (BOOL)stopCapturing {
@synchronized(self) {
// Continue playing music even after disconnected from a Room.
if (self.continuousMusic) {
return YES;
}
// If the renderer is runnning, we will not stop the audio unit.
if (!self.renderingContext->deviceContext && _enabled) {
[self stopAndTeardownAudioUnit];
}
self.capturingContext->deviceContext = NULL;
// We will make sure AVAudioEngine and AVAudioPlayerNode is accessed on the main queue.
dispatch_async(dispatch_get_main_queue(), ^{
if (self.recordFilePlayer.isPlaying) {
[self.recordFilePlayer stop];
}
if (self.recordEngine.isRunning) {
[self.recordEngine stop];
}
});
}
return YES;
}
#pragma mark - Private (AudioUnit callbacks)
static OSStatus ExampleAVAudioEngineDevicePlayoutCallback(void *refCon,
AudioUnitRenderActionFlags *actionFlags,
const AudioTimeStamp *timestamp,
UInt32 busNumber,
UInt32 numFrames,
AudioBufferList *bufferList) NS_AVAILABLE(NA, 11_0) {
assert(bufferList->mNumberBuffers == 1);
assert(bufferList->mBuffers[0].mNumberChannels <= 2);
assert(bufferList->mBuffers[0].mNumberChannels > 0);
AudioRendererContext *context = (AudioRendererContext *)refCon;
context->bufferList = bufferList;
int8_t *audioBuffer = (int8_t *)bufferList->mBuffers[0].mData;
UInt32 audioBufferSizeInBytes = bufferList->mBuffers[0].mDataByteSize;
// Pull decoded, mixed audio data from the media engine into the AudioUnit's AudioBufferList.
assert(audioBufferSizeInBytes == (bufferList->mBuffers[0].mNumberChannels * kAudioSampleSize * numFrames));
OSStatus outputStatus = noErr;
// Get the mixed audio data from AVAudioEngine's output node by calling the `renderBlock`
AVAudioEngineManualRenderingBlock renderBlock = (__bridge AVAudioEngineManualRenderingBlock)(context->renderBlock);
const AVAudioEngineManualRenderingStatus status = renderBlock(numFrames, bufferList, &outputStatus);
/*
* Render silence if there are temporary mismatches between CoreAudio and our rendering format or AVAudioEngine
* could not render the audio samples.
*/
if (numFrames > context->maxFramesPerBuffer || status != AVAudioEngineManualRenderingStatusSuccess) {
if (numFrames > context->maxFramesPerBuffer) {
NSLog(@"Can handle a max of %u frames but got %u.", (unsigned int)context->maxFramesPerBuffer, (unsigned int)numFrames);
}
*actionFlags |= kAudioUnitRenderAction_OutputIsSilence;
memset(audioBuffer, 0, audioBufferSizeInBytes);
}
return noErr;
}
static OSStatus ExampleAVAudioEngineDeviceRecordCallback(void *refCon,
AudioUnitRenderActionFlags *actionFlags,
const AudioTimeStamp *timestamp,
UInt32 busNumber,
UInt32 numFrames,
AudioBufferList *bufferList) NS_AVAILABLE(NA, 11_0) {
if (numFrames > kMaximumFramesPerBuffer) {
NSLog(@"Expected %u frames but got %u.", (unsigned int)kMaximumFramesPerBuffer, (unsigned int)numFrames);
return noErr;
}
AudioCapturerContext *context = (AudioCapturerContext *)refCon;
if (context->deviceContext == NULL) {
return noErr;
}
AudioBufferList *audioBufferList = context->bufferList;
audioBufferList->mBuffers[0].mDataByteSize = numFrames * sizeof(UInt16) * kPreferredNumberOfChannels;
// The buffer will be filled by VoiceProcessingIO AudioUnit
audioBufferList->mBuffers[0].mData = NULL;
OSStatus status = noErr;
status = AudioUnitRender(context->audioUnit,
actionFlags,
timestamp,
1,
numFrames,
audioBufferList);
AudioBufferList *mixedAudioBufferList = context->mixedAudioBufferList;
assert(mixedAudioBufferList != NULL);
assert(mixedAudioBufferList->mNumberBuffers == audioBufferList->mNumberBuffers);
for(int i = 0; i < audioBufferList->mNumberBuffers; i++) {
mixedAudioBufferList->mBuffers[i].mNumberChannels = audioBufferList->mBuffers[i].mNumberChannels;
mixedAudioBufferList->mBuffers[i].mDataByteSize = audioBufferList->mBuffers[i].mDataByteSize;
}
OSStatus outputStatus = noErr;
AVAudioEngineManualRenderingBlock renderBlock = (__bridge AVAudioEngineManualRenderingBlock)(context->renderBlock);
const AVAudioEngineManualRenderingStatus ret = renderBlock(numFrames, mixedAudioBufferList, &outputStatus);
if (ret != AVAudioEngineManualRenderingStatusSuccess) {
NSLog(@"AVAudioEngine failed mix audio");
}
int8_t *audioBuffer = (int8_t *)mixedAudioBufferList->mBuffers[0].mData;
UInt32 audioBufferSizeInBytes = mixedAudioBufferList->mBuffers[0].mDataByteSize;
if (context->deviceContext && audioBuffer) {
TVIAudioDeviceWriteCaptureData(context->deviceContext, audioBuffer, audioBufferSizeInBytes);
}
return noErr;
}
#pragma mark - Private (AVAudioSession and CoreAudio)
+ (nullable TVIAudioFormat *)activeFormat {
/*
* Use the pre-determined maximum frame size. AudioUnit callbacks are variable, and in most sitations will be close
* to the `AVAudioSession.preferredIOBufferDuration` that we've requested.
*/
const size_t sessionFramesPerBuffer = kMaximumFramesPerBuffer;
const double sessionSampleRate = [AVAudioSession sharedInstance].sampleRate;
return [[TVIAudioFormat alloc] initWithChannels:TVIAudioChannelsMono
sampleRate:sessionSampleRate
framesPerBuffer:sessionFramesPerBuffer];
}
+ (AudioComponentDescription)audioUnitDescription {
AudioComponentDescription audioUnitDescription;
audioUnitDescription.componentType = kAudioUnitType_Output;
audioUnitDescription.componentSubType = kAudioUnitSubType_VoiceProcessingIO;
audioUnitDescription.componentManufacturer = kAudioUnitManufacturer_Apple;
audioUnitDescription.componentFlags = 0;
audioUnitDescription.componentFlagsMask = 0;
return audioUnitDescription;
}
- (BOOL)setupAVAudioSession {
BOOL result = YES;
AVAudioSession *session = [AVAudioSession sharedInstance];
NSError *error = nil;
if (![session setPreferredSampleRate:kPreferredSampleRate error:&error]) {
NSLog(@"Error setting sample rate: %@", error);
result = NO;
}
if (![session setPreferredOutputNumberOfChannels:kPreferredNumberOfChannels error:&error]) {
NSLog(@"Error setting number of output channels: %@", error);
result = NO;
}
/*
* We want to be as close as possible to the 10 millisecond buffer size that the media engine needs. If there is
* a mismatch then TwilioVideo will ensure that appropriately sized audio buffers are delivered.
*/
if (![session setPreferredIOBufferDuration:kPreferredIOBufferDurationSec error:&error]) {
NSLog(@"Error setting IOBuffer duration: %@", error);
result = NO;
}
if (![session setCategory:AVAudioSessionCategoryPlayAndRecord error:&error]) {
NSLog(@"Error setting session category: %@", error);
result = NO;
}
if (![session setMode:AVAudioSessionModeVideoChat error:&error]) {
NSLog(@"Error setting session category: %@", error);
result = NO;
}
if (![session setActive:YES error:&error]) {
NSLog(@"Error activating AVAudioSession: %@", error);
result = NO;
}
if (session.maximumInputNumberOfChannels > 0) {
if (![session setPreferredInputNumberOfChannels:TVIAudioChannelsMono error:&error]) {
NSLog(@"Error setting number of input channels: %@", error);
result = NO;
}
}
return result;
}
- (BOOL)setupAndStartAudioUnit {
BOOL setupSuccessful = [self setupAudioUnitWithRenderContext:self.renderingContext
captureContext:self.capturingContext];
if (!setupSuccessful) {
NSLog(@"ExampleAVAudioEngineDevice failed to setup audio unit");
return NO;
}
BOOL startSuccessful = [self startAudioUnit];
if (!startSuccessful) {
NSLog(@"ExampleAVAudioEngineDevice failed to start audio unit");
[self stopAndTeardownAudioUnit];
return NO;
}
return YES;
}
- (void)stopAndTeardownAudioUnit {
@synchronized(self) {
if (self.audioUnit) {
[self stopAudioUnit];
[self teardownAudioUnit];
}
}
}
- (BOOL)setupAudioUnitWithRenderContext:(AudioRendererContext *)renderContext
captureContext:(AudioCapturerContext *)captureContext {
// Find and instantiate the VoiceProcessingIO audio unit.
AudioComponentDescription audioUnitDescription = [[self class] audioUnitDescription];
AudioComponent audioComponent = AudioComponentFindNext(NULL, &audioUnitDescription);
OSStatus status = AudioComponentInstanceNew(audioComponent, &_audioUnit);
if (status != 0) {
NSLog(@"Could not find VoiceProcessingIO AudioComponent instance!");
return NO;
}
/*
* Configure the VoiceProcessingIO audio unit. Our rendering format attempts to match what AVAudioSession requires
* to prevent any additional format conversions after the media engine has mixed our playout audio.
*/