iPhone microphone输入事件捕获
目的:
利用麦克风做为一种事件的输入方式
核心:
通过AudioSession与AudioQueue实现麦克风输入的数据捕捉.
开启AudioSession:
1. AudioSessionInitialize
2. AudioSessionSetProperty(kAudioSessionProperty_AudioCategory)
3. AudioSessionSetActive
建立声音格式:
1. 声音格式的数据结构AudioStreamBasicDescription
2. 使用kAudioFormatLinearPCM来做为声音格式
建立AudioQueue:
1. AudioQueueNewInput
2. AudioQueueStart
3. AudioQueueSetProperty(kAudioQueueProperty_EnableLevelMetering)
获取声音峰值数据:
1. 记录峰值的数据结构AudioQueueLevelMeterState
2. AudioQueueGetProperty(kAudioQueueProperty_CurrentLevelMeterDB)
关闭AudioQueue:
1. AudioQueueStop
2. AudioQueueDispose
代码:
#import
#import "MicrophoneTestViewController.h" static void MyInputBufferHandler(void * inUserData, AudioQueueRef inAQ, AudioQueueBufferRef inBuffer, const AudioTimeStamp * inStartTime, UInt32 inNumPackets, const AudioStreamPacketDescription* inPacketDesc) { // 如果要记录声音,可以在这里做记录处理. // 如果要分析声音数据,可以在这里做记录处理. } static void interruptionListener(void * inClientData, UInt32 inInterruptionState) { // 声音中断通知(BEGIN,END) } @implementation MicrophoneTestViewController // Implement viewDidLoad to do additional setup after loading the view, typically from a nib. - (void)viewDidLoad { [super viewDidLoad]; _averagePower.text = @"0"; _peakPower.text = @"0"; mQueue = NULL; _channelNumbers = [[NSArray alloc] initWithObjects:[NSNumber numberWithInt:0], nil]; _chan_lvls = (AudioQueueLevelMeterState*)malloc(sizeof(AudioQueueLevelMeterState) * [_channelNumbers count]); [self initAudioSession]; [NSTimer scheduledTimerWithTimeInterval:1.f/30.f target:self selector:@selector(_refresh) userInfo:nil repeats:YES ]; } - (void)didReceiveMemoryWarning { // Releases the view if it doesn't have a superview. [super didReceiveMemoryWarning]; // Release any cached data, images, etc that aren't in use. } - (void)viewDidUnload { // Release any retained subviews of the main view. // e.g. self.myOutlet = nil; [_channelNumbers release]; free(_chan_lvls); } - (void)dealloc { [super dealloc]; } -(void)initAudioSession { OSStatus error = AudioSessionInitialize(NULL, NULL, interruptionListener, self); if (error) printf("ERROR INITIALIZING AUDIO SESSION! %d/n", (int)error); else { UInt32 category = kAudioSessionCategory_PlayAndRecord; error = AudioSessionSetProperty(kAudioSessionProperty_AudioCategory, sizeof(category), &category); if (error) printf("couldn't set audio category!"); error = AudioSessionSetActive(true); if (error) printf("AudioSessionSetActive (true) failed"); } } -(void)setupAudioFormat:(UInt32)inFormatID { memset(&mFormat, 0, sizeof(mFormat)); UInt32 size = sizeof(mFormat.mSampleRate); OSStatus result = AudioSessionGetProperty(kAudioSessionProperty_CurrentHardwareSampleRate, &size, &mFormat.mSampleRate); size = sizeof(mFormat.mChannelsPerFrame); result = AudioSessionGetProperty(kAudioSessionProperty_CurrentHardwareInputNumberChannels, &size, &mFormat.mChannelsPerFrame); mFormat.mFormatID = inFormatID; if (inFormatID == kAudioFormatLinearPCM) { // if we want pcm, default to signed 16-bit little-endian mFormat.mFormatFlags = kLinearPCMFormatFlagIsSignedInteger | kLinearPCMFormatFlagIsPacked; mFormat.mBitsPerChannel = 16; mFormat.mBytesPerPacket = mFormat.mBytesPerFrame = (mFormat.mBitsPerChannel / 8) * mFormat.mChannelsPerFrame; mFormat.mFramesPerPacket = 1; } } -(void)startMicrophone { [self setupAudioFormat:kAudioFormatLinearPCM]; OSStatus result = AudioQueueNewInput(&mFormat, MyInputBufferHandler, NULL, NULL, NULL, 0, &mQueue); if (result == noErr) { result = AudioQueueStart(mQueue, NULL); if (result == noErr) { UInt32 val = 1; AudioQueueSetProperty(mQueue, kAudioQueueProperty_EnableLevelMetering, &val, sizeof(UInt32)); if (mFormat.mChannelsPerFrame != [_channelNumbers count]) { NSArray *chan_array; if (mFormat.mChannelsPerFrame < 2) chan_array = [[NSArray alloc] initWithObjects:[NSNumber numberWithInt:0], nil]; else chan_array = [[NSArray alloc] initWithObjects:[NSNumber numberWithInt:0], [NSNumber numberWithInt:1], nil]; [self setChannelNumbers:chan_array]; [chan_array release]; _chan_lvls = (AudioQueueLevelMeterState*)realloc(_chan_lvls, mFormat.mChannelsPerFrame * sizeof(AudioQueueLevelMeterState)); } return; } } // 失败 mQueue = NULL; NSLog(@"startMicrophone:失败."); return; } -(void)stopMicrophone { if (mQueue) { AudioQueueStop(mQueue, true); AudioQueueDispose(mQueue, true); mQueue = NULL; } } -(void)_refresh { if (mQueue) { UInt32 data_sz = sizeof(AudioQueueLevelMeterState) * [_channelNumbers count]; OSErr status = AudioQueueGetProperty(mQueue, kAudioQueueProperty_CurrentLevelMeterDB, _chan_lvls, &data_sz); if (status == noErr) { // 这里没有去处理多个通道的数据显示,直接就显示最后一个通道的结果了 // 这里的值就是我们打算用来做为一些触发机制的值了,需要用到的时候直接访问_chan_lvls这个数组 for (int i=0; i<[_channelNumbers count]; i++) { NSInteger channelIdx = [(NSNumber *)[_channelNumbers objectAtIndex:i] intValue]; if (channelIdx < [_channelNumbers count] && channelIdx <= 127) { _averagePower.text = [NSString stringWithFormat:@"%f", _chan_lvls[channelIdx].mAveragePower]; _peakPower.text = [NSString stringWithFormat:@"%f", _chan_lvls[channelIdx].mPeakPower]; } } } } } -(void)setChannelNumbers:(NSArray *)v { [v retain]; [_channelNumbers release]; _channelNumbers = v; } - (IBAction)startstop: (id) sender { if (mQueue) { [self stopMicrophone]; } else { [self startMicrophone]; } } @end