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138 lines
3.6 KiB
Objective-C
138 lines
3.6 KiB
Objective-C
//
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// AudioQueue.m
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// Clock Signal
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//
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// Created by Thomas Harte on 14/01/2016.
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// Copyright © 2016 Thomas Harte. All rights reserved.
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//
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#import "CSAudioQueue.h"
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@import AudioToolbox;
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#define AudioQueueBufferMaxLength 8192
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@implementation CSAudioQueue
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{
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AudioQueueRef _audioQueue;
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size_t _queuedSamples;
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}
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#pragma mark - AudioQueue callbacks
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- (void)audioQueue:(AudioQueueRef)theAudioQueue didCallbackWithBuffer:(AudioQueueBufferRef)buffer
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{
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_queuedSamples -= (size_t)(buffer->mAudioDataByteSize / sizeof(int16_t));
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if(_queuedSamples < 128) [self.delegate audioQueueDidCompleteBuffer:self];
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AudioQueueFreeBuffer(_audioQueue, buffer);
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}
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static void audioOutputCallback(
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void *inUserData,
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AudioQueueRef inAQ,
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AudioQueueBufferRef inBuffer)
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{
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[(__bridge CSAudioQueue *)inUserData audioQueue:inAQ didCallbackWithBuffer:inBuffer];
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}
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#pragma mark - Standard object lifecycle
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- (instancetype)initWithSamplingRate:(Float64)samplingRate
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{
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self = [super init];
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if(self)
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{
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_samplingRate = samplingRate;
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// determine preferred buffer sizes
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_preferredBufferSize = AudioQueueBufferMaxLength;
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while((Float64)_preferredBufferSize*100.0 > samplingRate) _preferredBufferSize >>= 1;
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/*
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Describe a mono 16bit stream of the requested sampling rate
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*/
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AudioStreamBasicDescription outputDescription;
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outputDescription.mSampleRate = samplingRate;
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outputDescription.mFormatID = kAudioFormatLinearPCM;
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outputDescription.mFormatFlags = kLinearPCMFormatFlagIsSignedInteger;
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outputDescription.mBytesPerPacket = 2;
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outputDescription.mFramesPerPacket = 1;
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outputDescription.mBytesPerFrame = 2;
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outputDescription.mChannelsPerFrame = 1;
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outputDescription.mBitsPerChannel = 16;
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outputDescription.mReserved = 0;
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// create an audio output queue along those lines
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if(!AudioQueueNewOutput(
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&outputDescription,
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audioOutputCallback,
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(__bridge void *)(self),
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NULL,
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kCFRunLoopCommonModes,
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0,
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&_audioQueue))
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{
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AudioQueueStart(_audioQueue, NULL);
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}
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}
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return self;
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}
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- (instancetype)init
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{
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return [self initWithSamplingRate:[[self class] preferredSamplingRate]];
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}
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- (void)dealloc
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{
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if(_audioQueue) AudioQueueDispose(_audioQueue, NO);
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}
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#pragma mark - Audio enqueuer
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- (void)enqueueAudioBuffer:(const int16_t *)buffer numberOfSamples:(size_t)lengthInSamples
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{
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AudioQueueBufferRef newBuffer;
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size_t bufferBytes = lengthInSamples * sizeof(int16_t);
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_queuedSamples += lengthInSamples;
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AudioQueueAllocateBuffer(_audioQueue, (UInt32)bufferBytes, &newBuffer);
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memcpy(newBuffer->mAudioData, buffer, bufferBytes);
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newBuffer->mAudioDataByteSize = (UInt32)bufferBytes;
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AudioQueueEnqueueBuffer(_audioQueue, newBuffer, 0, NULL);
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}
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#pragma mark - Sampling Rate getters
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+ (AudioDeviceID)defaultOutputDevice
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{
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AudioObjectPropertyAddress address;
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address.mSelector = kAudioHardwarePropertyDefaultOutputDevice;
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address.mScope = kAudioObjectPropertyScopeGlobal;
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address.mElement = kAudioObjectPropertyElementMaster;
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AudioDeviceID deviceID;
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UInt32 size = sizeof(AudioDeviceID);
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return AudioObjectGetPropertyData(kAudioObjectSystemObject, &address, sizeof(AudioObjectPropertyAddress), NULL, &size, &deviceID) ? 0 : deviceID;
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}
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+ (Float64)preferredSamplingRate
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{
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AudioObjectPropertyAddress address;
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address.mSelector = kAudioDevicePropertyNominalSampleRate;
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address.mScope = kAudioObjectPropertyScopeGlobal;
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address.mElement = kAudioObjectPropertyElementMaster;
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Float64 samplingRate;
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UInt32 size = sizeof(Float64);
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return AudioObjectGetPropertyData([self defaultOutputDevice], &address, sizeof(AudioObjectPropertyAddress), NULL, &size, &samplingRate) ? 0.0 : samplingRate;
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}
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@end
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