iPhone应用程序拾取声音 [英] iPhone App Pick Up Sound

问题描述

我正在尝试根据用户是否发出响亮的声音来执行某项操作。我不是想做任何语音识别或任何事情。只需根据iPhone是否发出响亮的声音做一个动作。

I am trying to do a certain action based on whether or not the user makes a loud sound. I'm not trying to do any voice recognition or anything. Just simply do an action based on whether the iPhone picks up a loud sound.

任何建议，教程，我在苹果开发者网站上找不到任何东西。我假设我没有正确地寻找或搜索。

Any suggestions, tutorials, I can't find anything on the apple developer site. I'm assuming i'm not looking or searching right.

推荐答案

最简单的方法是使用AudioQueue服务。以下是手册：
Apple AQ手册

The easiest thing for you do is to use the AudioQueue services. Here's the manual: Apple AQ manual

基本上，查找使用AudioQueueNewInput（）初始化事物的任何示例代码。这样的事情：

Basically, look for any example code that initialized things with AudioQueueNewInput(). Something like this:

    Status = AudioQueueNewInput(&_Description,
                                Audio_Input_Buffer_Ready,
                                self,
                                NULL,
                                NULL,
                                0,
                                &self->Queue);

完成后，您可以启用声级计量，如下所示：

Once you have that going, you can enable sound level metering with something like this:

// Turn on level metering (iOS 2.0 and later)
UInt32 on = 1;
AudioQueueSetProperty(self->Queue,kAudioQueueProperty_EnableLevelMetering,&on,sizeof(on));

您将拥有一个针对每个音频数据块调用的回调例程。在其中，您可以使用以下内容检查当前的仪表级别：

You will have a callback routine that is invoked for each chunk of audio data. In it, you can check the current meter levels with something like this:

//
//  Check metering levels and detect silence
//
AudioQueueLevelMeterState meters[1];
UInt32 dlen = sizeof(meters);
Status = AudioQueueGetProperty(_Queue,kAudioQueueProperty_CurrentLevelMeterDB,meters,&dlen);
if (Status == 0) {
    if (meters[0].mPeakPower > _threshold) {
        silence = 0.0;     // reset silence timer
    } else {
        silence += time;                
    }
}

//
//  Notify observers of incoming data.
//
if (delegate) {
    [delegate audioMeter:meters[0].mPeakPower duration:time];
    [delegate audioData:Buffer->mAudioData size:Buffer->mAudioDataByteSize];
}

或者，在您的情况下，您可以检测分贝水平，而不是沉默超过某个值足够长的时间。请注意，您将看到的分贝值范围大约为-70.0（对于死静音），对于非常响亮的事物，大约为0.0db。在指数范围内。您必须使用它来查看哪些值适用于您的特定应用程序。

Or, in your case, instead of silence you can detect if the decibel level is over a certain value for long enough. Note that the decibel values you will see will range from about -70.0 for dead silence, up to 0.0db for very loud things. On an exponential scale. You'll have to play with it to see what values work for your particular application.

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