使用Core Audio捕获延迟数据

Question

我编写了这段代码，使用Audio ToolBox框架创建了一个音频文件sine.aif。

我有兴趣在不运行手机的情况下捕获此文件的数据延迟，只需在命令行上运行它并捕获时间。这可能吗？我对Core Audio的了解不多。

以下是代码：

#import <Foundation/Foundation.h>
#import <AudioToolbox/AudioToolbox.h>

#define SAMPLE_RATE 44100                   
#define DURATION 5.0                        
#define FILENAME_FORMAT @"%0.3f-sine.aif"  

int main(int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc]init];

    if(argc < 2) {
        printf("Usage:CAToneFileGenerator 261.526\n");
        return -1;
    }

    double hz = atof(argv[1]); 
    assert (hz > 0);
    NSLog (@"generating %f hz tone", hz);

    NSString *fileName = [NSString stringWithFormat:FILENAME_FORMAT, hz]; 

    NSString *filePath = [[[NSFileManager defaultManager]currentDirectoryPath]stringByAppendingPathComponent:fileName];

    NSURL *fileURL = [NSURL fileURLWithPath:filePath];

    //Prepare the format
    AudioStreamBasicDescription asbd;   
    memset(&asbd, 0, sizeof(asbd));     
    asbd.mSampleRate = SAMPLE_RATE;     

    asbd.mFormatID = kAudioFormatLinearPCM;
    asbd.mFormatFlags = kAudioFormatFlagIsBigEndian | kAudioFormatFlagIsSignedInteger | kAudioFormatFlagIsPacked;
    asbd.mBitsPerChannel = 16;
    asbd.mChannelsPerFrame = 1;
    asbd.mFramesPerPacket = 1;
    asbd.mBytesPerFrame = 2;
    asbd.mBytesPerPacket = 2;

    //Set up the file
    AudioFileID audioFile;
    OSStatus audioErr = noErr;
    audioErr = AudioFileCreateWithURL((CFURLRef)fileURL, kAudioFileAIFFType, &asbd, kAudioFileFlags_EraseFile, &audioFile); 
    assert(audioErr == noErr);

    //Start writing samples
    long maxSampleCount = SAMPLE_RATE * DURATION; 
    //NSLog (@"maxSampleCount %long", maxSampleCount);
    long sampleCount = 0;
    UInt32 bytesToWrite = 2;
    double wavelengthInSamples = SAMPLE_RATE / hz; 
    NSLog (@"wavelengthInSamples %f", wavelengthInSamples);

    while (sampleCount < maxSampleCount) {
        for (int i=0; i < wavelengthInSamples; i++) {
            // sine wave
            SInt16 sample = CFSwapInt16HostToBig ((SInt16)SHRT_MAX * sin(2 * M_PI * (i / wavelengthInSamples)));
            audioErr = AudioFileWriteBytes(audioFile, false, sampleCount*2, &bytesToWrite, &sample);
            assert(audioErr == noErr);
            sampleCount++;
        }
    }
    audioErr = AudioFileClose(audioFile); 
    assert(audioErr == noErr);
    NSLog (@"wrote %d samples", sampleCount);

    [pool drain];
    return 0;
    }