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我正在嘗試創建一個應用程序,它可以監聽並計算iPhone周圍環境中的平均音頻電平。一旦這個「平均」水平被超越,說有人喊,那麼應用程序會通知用戶平均聲級已被超過。你能否給我提供一個示例代碼或易於遵循的教程,因爲我很新,而且我遇到的所有教程都太難理解,或者不適用於我的XCODE版本(4.3.2 ) 謝謝。音頻電平檢測
我正在嘗試創建一個應用程序,它可以監聽並計算iPhone周圍環境中的平均音頻電平。一旦這個「平均」水平被超越,說有人喊,那麼應用程序會通知用戶平均聲級已被超過。你能否給我提供一個示例代碼或易於遵循的教程,因爲我很新,而且我遇到的所有教程都太難理解,或者不適用於我的XCODE版本(4.3.2 ) 謝謝。音頻電平檢測
赫雷什計算輸出並打印一個例子:
-(void)loadView{
/*****ALLOC VIEW*****/
CGRect applicationFrame = [[UIScreen mainScreen] applicationFrame];
UIView *contentView = [[UIView alloc] initWithFrame:applicationFrame];
contentView.backgroundColor = [UIColor whiteColor];
self.view = contentView;
[contentView release];
}
- (void)viewDidLoad {
[super viewDidLoad];
UIImageView *bg = [[UIImageView alloc] initWithFrame:CGRectMake(0, 90, 320, 247)];
bg.image = [UIImage imageNamed:@"BF_pre.png"];
[self.view addSubview: bg];//IGNORE
NSURL *url = [NSURL fileURLWithPath:@"/dev/null"];
NSDictionary *settings = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithFloat: 44100.0], AVSampleRateKey,
[NSNumber numberWithInt: kAudioFormatAppleLossless], AVFormatIDKey,
[NSNumber numberWithInt: 1], AVNumberOfChannelsKey,
[NSNumber numberWithInt: AVAudioQualityMax], AVEncoderAudioQualityKey,
nil];
NSError *error;
recorder = [[AVAudioRecorder alloc] initWithURL:url settings:settings error:&error];
if (recorder) {
[recorder prepareToRecord];
recorder.meteringEnabled = YES;
[recorder record];
levelTimer = [NSTimer scheduledTimerWithTimeInterval: 0.03 target: self selector: @selector(levelTimerCallback:) userInfo: nil repeats: YES];
}
}
- (void)levelTimerCallback:(NSTimer *)timer {
[recorder updateMeters];
const double ALPHA = 0.05;
double peakPowerForChannel = pow(10, (0.05 * [recorder peakPowerForChannel:0]));
lowPassResults = ALPHA * peakPowerForChannel + (1.0 - ALPHA) * lowPassResults;
NSLog(@"%f",(lowPassResults*100.0f));
}
- (void)dealloc {
[levelTimer release];
[recorder release];
[super dealloc];
}
這對我工作,謝謝 – channi
這是一個令人難以置信廣泛的問題.. – Lloyd
只需計算RMS功率在合理的時間間隔。如果您不確定如何執行此操作,請搜索「RMS」。 –