AVAudioRecorder记录空白文件

Question

以下是我的记录按钮方法的内容.它创建了所需的文件,但无论我记录多长时间,创建的文件总是4kb和0秒,我无法弄清楚它为什么无效.对于averagePowerPerChannel,计量也返回-120,我假设它是因为文件已损坏.

NSDictionary *recordSettings = [NSDictionary
                                    dictionaryWithObjectsAndKeys:
                                    [NSNumber numberWithInt:AVAudioQualityMin],
                                    AVEncoderAudioQualityKey,
                                    [NSNumber numberWithInt:16],
                                    AVEncoderBitRateKey,
                                    [NSNumber numberWithInt: 2],
                                    AVNumberOfChannelsKey,
                                    [NSNumber numberWithFloat:44100.0], 
                                    AVSampleRateKey,
                                    nil];
    NSError *error;
    NSArray *dirPaths;
    NSString *docsDir;

    dirPaths = NSSearchPathForDirectoriesInDomains(
                                                   NSDocumentDirectory, NSUserDomainMask, YES);
    docsDir = [dirPaths objectAtIndex:0];
    NSString *soundFilePath = [docsDir
                               stringByAppendingPathComponent:@"sound.caf"];

    NSURL *soundFileURL = [NSURL fileURLWithPath:soundFilePath];

    self.shotRecorder = [[AVAudioRecorder alloc] initWithURL:soundFileURL settings:recordSettings error:&error];
    self.shotRecorder.delegate = self;

    if (error)
    {
        NSLog(@"error: %@", [error localizedDescription]);

    } else {
        [self.shotRecorder prepareToRecord];
        self.shotRecorder.meteringEnabled = YES;
        [self.shotRecorder record];
        shotTimer = [NSTimer scheduledTimerWithTimeInterval: 0.03 target: self selector: @selector(levelTimerCallback:) userInfo: nil repeats: YES];
    }

Answer 1

在开始录制之前,请将应用的AudioSession设置为支持录制的会话类型之一.例如,在开始录制之前调用它:

[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryRecord error:&error];

如果您尝试将AudioSession设置为不支持录制的类型进行录制,则代码似乎执行正常,但会导致您描述的空4kb音频文件.

要稍后播放该文件,请确保将类别设置回支持播放的类别,例如AVAudioSessionCategoryPlayback或AVAudioSessionCategoryPlayAndRecord.