采集音视频后无法播放系统声音

Question

我正在用AVfoudnation重新编码音频/视频。在开始捕获视频/音频之前，我需要使用系统声音播放声音。这是正确的第一次，但当我尝试这样做第二次，系统奥迪不播放。我的猜测是AVfoundation中的某些内容没有正确发布。

在我的应用程序删除中，我在applicationDidFinishLaunching方法中有以下代码：

VKRSAppSoundPlayer *aPlayer = [[VKRSAppSoundPlayer alloc] init];
[aPlayer addSoundWithFilename:@"sound1" andExtension:@"caf"];
self.appSoundPlayer = aPlayer;
[aPlayer release];

还有这个方法

- (void)playSound:(NSString *)sound
{
    [appSoundPlayer playSound:sound];
}

如你所见，我使用的是VKRSAppSoundPlayer，它工作得很好！

在视图中，我有这样的代码：

- (void) startSession
{
    self.session = [[AVCaptureSession  alloc] init];

    [session beginConfiguration];
    if([session canSetSessionPreset:AVCaptureSessionPreset640x480])
        session.sessionPreset =  AVCaptureSessionPresetMedium; 

    [session commitConfiguration];


    CALayer *viewLayer = [videoPreviewView layer];

    AVCaptureVideoPreviewLayer *captureVideoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session];

    captureVideoPreviewLayer.frame = viewLayer.bounds;

    [viewLayer addSublayer:captureVideoPreviewLayer];

    self.videoInput = [AVCaptureDeviceInput deviceInputWithDevice:[self frontFacingCameraIfAvailable] error:nil];
    self.audioInput = [AVCaptureDeviceInput deviceInputWithDevice:[self audioDevice] error:nil];

    if(videoInput){
        self.videoOutput = [[AVCaptureMovieFileOutput alloc] init];

        [session addOutput:videoOutput];
        //[videoOutput release];

        if([session canAddInput:videoInput]){
            //[session beginConfiguration];
            [session addInput:videoInput];

        }
        //[videoInput release];

        [session removeInput:[self audioInput]];
        if([session canAddInput:audioInput]){
            [session addInput:audioInput];
        }
        //[audioInput release];


        if([session canAddInput:audioInput])
            [session addInput:audioInput];


        NSLog(@"startRunning!");
        [session startRunning];  

        [self startRecording];


        if(![self recordsVideo])
            [self showAlertWithTitle:@"Video Recording Unavailable" msg:@"This device can't record video."];

    }
}

- (void) stopSession
{
    [session stopRunning];
    [session release];   
}


- (AVCaptureDevice *)frontFacingCameraIfAvailable
{
    NSArray *videoDevices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
    AVCaptureDevice *captureDevice = nil;

    Boolean cameraFound = false;

    for (AVCaptureDevice *device in videoDevices)
    {
        NSLog(@"1 frontFacingCameraIfAvailable %d", device.position);
        if (device.position == AVCaptureDevicePositionBack){
            NSLog(@"1 frontFacingCameraIfAvailable FOUND");

            captureDevice = device;
            cameraFound = true;
            break;
        }
    }

    if(cameraFound == false){
        for (AVCaptureDevice *device in videoDevices)
        {
            NSLog(@"2 frontFacingCameraIfAvailable %d", device.position);
            if (device.position == AVCaptureDevicePositionFront){
                NSLog(@"2 frontFacingCameraIfAvailable FOUND");

                captureDevice = device;
                break;
            }
        }
    }

    return captureDevice;
}

- (AVCaptureDevice *) audioDevice
{
    NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeAudio];
    if ([devices count] > 0) {
        return [devices objectAtIndex:0];
    }
    return nil;
}

- (void) startRecording
{
#if _Multitasking_
    if ([[UIDevice currentDevice] isMultitaskingSupported]) {
        [self setBackgroundRecordingID:[[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{}]];
    }
#endif

    [videoOutput startRecordingToOutputFileURL:[self generatenewVideoPath] 
                             recordingDelegate:self];
}

- (void) stopRecording
{
    [videoOutput stopRecording];

}

- (void)captureOutput:(AVCaptureFileOutput *)captureOutput 
didFinishRecordingToOutputFileAtURL:(NSURL *)outputFileURL 
      fromConnections:(NSArray *)connections error:(NSError *)error
{
    NSFileManager *man = [[NSFileManager alloc] init];
    NSDictionary *attrs = [man attributesOfItemAtPath: [outputFileURL path] error: NULL];
    NSString *fileSize = [NSString stringWithFormat:@"%llu", [attrs fileSize]];


    // close this screen
    [self exitScreen];
}

-(BOOL)recordsVideo
{
    AVCaptureConnection *videoConnection = [AVCamUtilities connectionWithMediaType:AVMediaTypeVideo 
                                                                   fromConnections:[videoOutput connections]];
    return [videoConnection isActive];
}

-(BOOL)recordsAudio
{
    AVCaptureConnection *audioConnection = [AVCamUtilities connectionWithMediaType:AVMediaTypeAudio 
                                                                   fromConnections:[videoOutput connections]];
    return [audioConnection isActive];
}

如果我执行videoInput release；和audioInput release；我得到一个严重的访问错误。这就是为什么它们被注释掉的原因。这可能是问题的一部分。

如果我尝试播放系统声音n次，它可以工作，但如果我首先进入录制脚本，它将无法工作。

有什么想法吗？

Answer 1

发布AVCaptureSession的正确方法如下：

- (void) destroySession {

    // Notify the view that the session will end
    if ([delegate respondsToSelector:@selector(captureManagerSessionWillEnd:)]) {
        [delegate captureManagerSessionWillEnd:self];
    }

    // remove the device inputs
    [session removeInput:[self videoInput]];
    [session removeInput:[self audioInput]];

    // release
    [session release];

    // remove AVCamRecorder
    [recorder release];

    // Notify the view that the session has ended
    if ([delegate respondsToSelector:@selector(captureManagerSessionEnded:)]) {
        [delegate captureManagerSessionEnded:self];
    }
}

如果你有某种发布问题(访问不好)，我可以建议你把你的代码从当前“混乱”的项目中转移到其他一些新项目中，并在那里调试问题。

当我遇到类似的问题时，我就这么做了。我在Github上分享了它，你可能会发现这个项目很有用：AVCam-CameraReleaseTest