iPhone - 使用 AVAudioRecorder 录音

Question

我已经按照上面的示例代码，一切似乎都工作正常，没有一个错误，语音文件 (.caf) 已成功创建。

唯一的问题是文件总是 29kb 并且没有任何声音。

我正在我的模拟器中运行该应用程序，不确定我是否错过了任何东西。我需要设置什么才能让我的模拟器正常工作吗？

下面是我的代码：

-(IBAction) startRecording
{
    NSLog(@"startRecording");
[audioRecorder release];
audioRecorder = nil;

// Init audio with record capability
AVAudioSession *audioSession = [AVAudioSession sharedInstance];
[audioSession setCategory:AVAudioSessionCategoryRecord error:nil];

NSMutableDictionary *recordSettings = [[NSMutableDictionary alloc] initWithCapacity:10];
if(recordEncoding == ENC_PCM)
{
    [recordSettings setObject:[NSNumber numberWithInt: kAudioFormatLinearPCM] forKey: AVFormatIDKey];
    [recordSettings setObject:[NSNumber numberWithFloat:44100.0] forKey: AVSampleRateKey];
    [recordSettings setObject:[NSNumber numberWithInt:2] forKey:AVNumberOfChannelsKey];
    [recordSettings setObject:[NSNumber numberWithInt:16] forKey:AVLinearPCMBitDepthKey];
    [recordSettings setObject:[NSNumber numberWithBool:NO] forKey:AVLinearPCMIsBigEndianKey];
    [recordSettings setObject:[NSNumber numberWithBool:NO] forKey:AVLinearPCMIsFloatKey];   
}
else
{
    NSNumber *formatObject;

    switch (recordEncoding) {
        case (ENC_AAC): 
            formatObject = [NSNumber numberWithInt: kAudioFormatMPEG4AAC];
            break;
        case (ENC_ALAC):
            formatObject = [NSNumber numberWithInt: kAudioFormatAppleLossless];
            break;
        case (ENC_IMA4):
            formatObject = [NSNumber numberWithInt: kAudioFormatAppleIMA4];
            break;
        case (ENC_ILBC):
            formatObject = [NSNumber numberWithInt: kAudioFormatiLBC];
            break;
        case (ENC_ULAW):
            formatObject = [NSNumber numberWithInt: kAudioFormatULaw];
            break;
        default:
            formatObject = [NSNumber numberWithInt: kAudioFormatAppleIMA4];
    }

    [recordSettings setObject:formatObject forKey: AVFormatIDKey];
    [recordSettings setObject:[NSNumber numberWithFloat:44100.0] forKey: AVSampleRateKey];
    [recordSettings setObject:[NSNumber numberWithInt:2] forKey:AVNumberOfChannelsKey];
    [recordSettings setObject:[NSNumber numberWithInt:12800] forKey:AVEncoderBitRateKey];
    [recordSettings setObject:[NSNumber numberWithInt:16] forKey:AVLinearPCMBitDepthKey];
    [recordSettings setObject:[NSNumber numberWithInt: AVAudioQualityHigh] forKey: AVEncoderAudioQualityKey];
}

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];

NSString *sourceFilename = [[NSString alloc] initWithString:@"r.caf"];
NSString *sourcePath = [documentsDirectory stringByAppendingPathComponent:sourceFilename];
[sourceFilename release];

//[[NSFileManager defaultManager] createFileAtPath:sourcePath contents:nil attributes:nil];

NSURL *url = [NSURL fileURLWithPath:sourcePath];

NSError *error = nil;
audioRecorder = [[ AVAudioRecorder alloc] initWithURL:url settings:recordSettings error:&error];

audioRecorder.delegate = self;

if(!audioRecorder){
    NSLog(@"recorder: %@ %d %@", [error domain], [error code], [[error userInfo] description]);
    UIAlertView *alert =
    [[UIAlertView alloc] initWithTitle: @"Warning"
                               message: [error localizedDescription]
                              delegate: nil
                     cancelButtonTitle:@"OK"
                     otherButtonTitles:nil];
    [alert show];
    [alert release];
    return;
}

if ([audioRecorder prepareToRecord] == YES){
    [audioRecorder record];
}else {
    int errorCode = CFSwapInt32HostToBig ([error code]); 
    NSLog(@"Error: %@ [%4.4s])" , [error localizedDescription], (char*)&errorCode); 

}
NSLog(@"recording");
}

请指教。谷歌搜索上下，但无法找到它的原因。我是否需要安装 soundflower 才能使其工作？

Answer 1

发现kAudioFormatMPEG4AAC的音频格式，AVEncoderBitRateKey不能设置为12800，注释掉比特率语句，录音成功。

尚未确定 kAudioFormatMPEG4AAC 的正确和支持的比特率应该是多少，但这至少是问题的答案，对于像我这样遇到相同情况的任何人。

:)

Answer 2

这一切都很好，只是您的编码器比特率应该是 128000 (128k) 而不是 12800 (12.8k)。