iPhone 7 Plus - AVFoundation 双摄像头

Question

我目前正在积极研究这个问题，但既然 iPhone 7 Plus 有双摄像头系统，AVFoundation 是否允许您同时处理来自每个特定摄像头的视频帧？

我 thinking/hoping 我能够在给定特定位置的情况下同时处理来自两个 AVCaptureDevice 实例的输出。

Answer 1

在更新的 AVFoundation 文档 (AVCaptureDeviceType) 中有新的设备类型：builtInWideAngleCamera 和 builtInTelephotoCamera。因此，应该可以创建多个捕获会话并同时从他们两个那里获得反馈。

Answer 2

您一次只能将一个摄像头添加到一个 AVCaptureSession。例如，您可以在前置和后置摄像头之间切换，但不能同时使用两者。 7 Plus上的两个后置摄像头也是一样，你必须选择其中一个。但是，有一个小区别，因为您还可以调用 "duo camera" 在缩放时合并来自两个摄像头的图像。但这仅适用于静态照片，您将只能获得一个 image/capture 缓冲区。对于视频，您必须选择任一摄像头。

要选择相机，您可以使用新的 AVCaptureDeviceDiscoverySession。要使用双摄像头：

@property (nonatomic) AVCaptureDevice *backCamera;
@property (nonatomic) AVCaptureDeviceInput *backCameraInput;


if([AVCaptureDeviceDiscoverySession class]){
    NSArray *allTypes = @[AVCaptureDeviceTypeBuiltInDuoCamera, AVCaptureDeviceTypeBuiltInWideAngleCamera, AVCaptureDeviceTypeBuiltInTelephotoCamera ];
    AVCaptureDeviceDiscoverySession *discoverySession = [AVCaptureDeviceDiscoverySession discoverySessionWithDeviceTypes:allTypes mediaType:AVMediaTypeVideo position:AVCaptureDevicePositionBack];

    for(AVCaptureDevice *device in discoverySession.devices) {
        if(device.deviceType== AVCaptureDeviceTypeBuiltInDuoCamera){
            self.backCamera = device;
            self.backCameraInput = [AVCaptureDeviceInput deviceInputWithDevice:self.backCamera error:&error];
        }
    }
}

if(!self.backCamera){
    self.backCamera = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    self.backCameraInput = [AVCaptureDeviceInput deviceInputWithDevice:self.backCamera error:&error];
}

分别使用广角和长焦相机

@property (nonatomic) AVCaptureDevice *backCamera;
@property (nonatomic) AVCaptureDeviceInput *backCameraInput;
@property (nonatomic) AVCaptureDevice *teleCamera;
@property (nonatomic) AVCaptureDeviceInput *teleCameraInput;


if([AVCaptureDeviceDiscoverySession class]){
    NSArray *allTypes = @[AVCaptureDeviceTypeBuiltInDuoCamera, AVCaptureDeviceTypeBuiltInWideAngleCamera, AVCaptureDeviceTypeBuiltInTelephotoCamera ];
    AVCaptureDeviceDiscoverySession *discoverySession = [AVCaptureDeviceDiscoverySession discoverySessionWithDeviceTypes:allTypes mediaType:AVMediaTypeVideo position:AVCaptureDevicePositionBack];

    for(AVCaptureDevice *device in discoverySession.devices) {
        if(device.deviceType==AVCaptureDeviceTypeBuiltInWideAngleCamera){
            self.backCamera = device;
            self.backCameraInput = [AVCaptureDeviceInput deviceInputWithDevice:self.backCamera error:&error];
        }

        if(device.deviceType==AVCaptureDeviceTypeBuiltInTelephotoCamera){
            self.teleCamera = device;
            self.teleCameraInput = [AVCaptureDeviceInput deviceInputWithDevice:self.teleCamera error:&error];
        }
    }
}

if(!self.backCamera){
    self.backCamera = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    self.backCameraInput = [AVCaptureDeviceInput deviceInputWithDevice:self.backCamera error:&error];
}

如果您不这样做，或者保留您的旧代码，即使您进行缩放，您也只能使用广角镜头。

编辑：在 iOS11 中有一个名为 dualCameraDualPhotoDeliveryEnabled 的新 AVCapturePhotoSettings。它允许您同时拍摄两张静止图像，但是，没有 streaming/video.

iPhone 7 Plus - AVFoundation 双摄像头

iPhone 7 Plus - AVFoundation dual camera

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