Question

我正在尝试实施条形码扫描仪。我有一个AVCaptureSession从AVCaptureDevice接收视频。我想支持所有方向。使用以下代码，当我运行应用程序时，纵向方向的一切都很好。但是在横向方向上，视图会旋转但视频输入不会旋转。所以我最终得到了一张90度的旋转视频。

当我实现 - （NSUInteger）supportedInterfaceOrientations方法时，一切都被锁定到纵向位置。

有谁能告诉我如何解决这个问题？

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    [self setupCaptureSession];

    _previewLayer.frame = _previewView.bounds;
    _previewView.center = self.view.center;
    _previewView.backgroundColor = [UIColor redColor];
    [_previewView.layer addSublayer:_previewLayer];

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(applicationWillEnterForeground:) name:UIApplicationWillEnterForegroundNotification object:nil];

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(applicationDidEnterBackground:) name:UIApplicationDidEnterBackgroundNotification object:nil];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

-(void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    [self startRunning];
}

-(void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
    [self stopRunning];
}

-(void) setupCaptureSession
{
    if (_captureSession)
        return;

    _videoDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

    if (!_videoDevice)
    {
        NSLog(@"No video camera on this device");
        return;
    }

    _captureSession = [[AVCaptureSession alloc]init];

    _videoInput = [[AVCaptureDeviceInput alloc]initWithDevice:_videoDevice error:nil];

    if ([_captureSession canAddInput:_videoInput])
    {
        [_captureSession addInput:_videoInput];
    }

    _previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:_captureSession];

    _previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;

}

-(void) startRunning
{
    if (_running)
        return;

    [_captureSession startRunning];
    _running = YES;
}

- (void) stopRunning
{
    if (!_running)
        return;

    [_captureSession stopRunning];
    _running = NO;
}

/*
-(NSUInteger)supportedInterfaceOrientations
{
    return UIInterfaceOrientationLandscapeLeft|UIInterfaceOrientationLandscapeRight|UIInterfaceOrientationPortrait|UIInterfaceOrientationPortraitUpsideDown;
}

*/

编辑：

我尝试了以下代码，但previewLayer方向仍然是颠倒/横向。

    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(orientationChanged)
                                                 name:UIDeviceOrientationDidChangeNotification
                                               object:nil];
-(void) orientationChanged
{
    if (self.interfaceOrientation == UIInterfaceOrientationPortraitUpsideDown)
        [_previewLayer.connection setVideoOrientation:AVCaptureVideoOrientationPortraitUpsideDown];

    if (self.interfaceOrientation == UIInterfaceOrientationPortrait)
        [_previewLayer.connection setVideoOrientation:AVCaptureVideoOrientationPortrait];

    if (self.interfaceOrientation == UIInterfaceOrientationLandscapeLeft)
        [_previewLayer.connection setVideoOrientation:AVCaptureVideoOrientationLandscapeLeft];

    if (self.interfaceOrientation == UIInterfaceOrientationLandscapeRight)
        [_previewLayer.connection setVideoOrientation:AVCaptureVideoOrientationLandscapeRight];
}

Answer 1

用以下

修复了它

-(void) orientationChanged {
    UIDeviceOrientation deviceOrientation = [UIDevice currentDevice].orientation;
    if (deviceOrientation == UIInterfaceOrientationPortraitUpsideDown)
        [_previewLayer.connection setVideoOrientation:AVCaptureVideoOrientationPortraitUpsideDown];

    else if (deviceOrientation == UIInterfaceOrientationPortrait)
        [_previewLayer.connection setVideoOrientation:AVCaptureVideoOrientationPortrait];

    else if (deviceOrientation == UIInterfaceOrientationLandscapeLeft)
        [_previewLayer.connection setVideoOrientation:AVCaptureVideoOrientationLandscapeLeft];

    else
        [_previewLayer.connection setVideoOrientation:AVCaptureVideoOrientationLandscapeRight];
}

Answer 2

要在捕获的媒体中反映设备方向更改，您需要设置输出捕获连接的videoOrientation属性。

AVCaptureOutput* output = <# Your capture output device #>; //reference to your device output, possibly of AVCaptureStillImageOutput or AVCaptureMovieFileOutput type
AVCaptureConnection* connection = [output connectionWithMediaType:AVMediaTypeVideo];
if ([connection isVideoOrientationSupported]) {
    connection.videoOrientation = [self videoOrientationFromDeviceOrientation];
}

以下方法根据设备方向返回视频方向：

-(AVCaptureVideoOrientation)videoOrientationFromDeviceOrientation {
    AVCaptureVideoOrientation result = [UIDevice currentDevice].orientation;
    if ( result == UIDeviceOrientationLandscapeLeft )
        result = AVCaptureVideoOrientationLandscapeRight;
    else if ( result == UIDeviceOrientationLandscapeRight )
        result = AVCaptureVideoOrientationLandscapeLeft;
    return result;
}

希望你会发现它有用。

Answer 3

我没有关于这个问题的新信息，但我认为两个答案都很好，而且只是半个故事。我今天在这个问题上工作了很长时间，并没有找到适合我情况的正确的答案。但差不多。

实际上您需要遵守这两种解决方案。您肯定需要相应地旋转预览图层。但是如果你想让镜头处于相同的方向（而不是以某种方式切断），你需要做一个组合。

此外，我还要修复此问题：-[UIDevice orientation]可让您了解房间内设备的真实方向。但您可能更好地依赖应用程序的界面方向，如下面的代码所示。

在我的情况下，我只支持横向（两者）并且有一个写入磁盘的录像机。在这里，我使用一个块来通知，因为我喜欢它们很多;）

// @property (nonatomic, retain) AVCaptureMovieFileOutput *videoFileOutput;
// @property (nonatomic, retain) AVCaptureVideoPreviewLayer *videoPreviewLayer;

- (void)viewDidLoad {
    [super viewDidLoad];

    void (^observerHandler)(NSNotification *) = ^(NSNotification *note) {
        switch ([[UIApplication sharedApplication] statusBarOrientation]) {
            case UIInterfaceOrientationLandscapeRight:
                [[[self videoPreviewLayer] connection] setVideoOrientation:AVCaptureVideoOrientationLandscapeRight];
                [[[self videoFileOutput] connectionWithMediaType:AVMediaTypeVideo] setVideoOrientation:AVCaptureVideoOrientationLandscapeRight];
                break;

            case UIInterfaceOrientationLandscapeLeft:
                [[[self videoPreviewLayer] connection] setVideoOrientation:AVCaptureVideoOrientationLandscapeLeft];
                [[[self videoFileOutput] connectionWithMediaType:AVMediaTypeVideo] setVideoOrientation:AVCaptureVideoOrientationLandscapeLeft];
                break;

            default:
                break;
        }
    };

    [self setOrientationObserver:[[NSNotificationCenter defaultCenter] addObserverForName:UIDeviceOrientationDidChangeNotification object:nil queue:[NSOperationQueue currentQueue] usingBlock:observerHandler]];
}

具有多个方向问题的AVCaptureSession

3 个答案: