iPhone音频分析 [英] iPhone audio analysis

问题描述

我正在研究开发一款iPhone应用程序，它可能会对从标准手机麦克风接收的音频进行简单分析。具体来说，我对麦克风图片的高点和低点感兴趣，而且介于两者之间的所有内容都与我无关。

有没有一个应用程序已经这样做（只是这样我可以看到它的能力）？我应该在哪里开始使用这些代码？

感谢您的帮助。

I'm looking into developing an iPhone app that will potentially involve a "simple" analysis of audio it is receiving from the standard phone mic. Specifically, I am interested in the highs and lows the mic pics up, and really everything in between is irrelevant to me.

Is there an app that does this already (just so I can see what its capable of)? And where should I look to get started on such code?

Thanks for your help.

推荐答案

查看音频队列框架。这就是我用来获得高水位的原因：

Look in the Audio Queue framework. This is what I use to get a high water mark:

AudioQueueRef audioQueue; // Imagine this is correctly set up
UInt32 dataSize = sizeof(AudioQueueLevelMeterState) * recordFormat.mChannelsPerFrame;
AudioQueueLevelMeterState *levels = (AudioQueueLevelMeterState*)malloc(dataSize);

float channelAvg = 0;

OSStatus rc = AudioQueueGetProperty(audioQueue, kAudioQueueProperty_CurrentLevelMeter, levels, &dataSize);
if (rc) {
    NSLog(@"AudioQueueGetProperty(CurrentLevelMeter) returned %@", rc);
} else {    
    for (int i = 0; i < recordFormat.mChannelsPerFrame; i++) {
        channelAvg += levels[i].mPeakPower;
    }
}
free(levels);

// This works because one channel always has an mAveragePower of 0.
return channelAvg;

您可以在dB Free Scale（使用kAudioQueueProperty_CurrentLevelMeterDB）中获得峰值功率，或者只是作为浮点数获得interval [0.0,1.0]（使用kAudioQueueProperty_CurrentLevelMeter）。

You can get peak power in either dB Free Scale (with kAudioQueueProperty_CurrentLevelMeterDB) or simply as a float in the interval [0.0, 1.0] (with kAudioQueueProperty_CurrentLevelMeter).

这篇关于iPhone音频分析的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！