替代已棄用的AVCaptureConnection幀持續時間屬性？

Question

根據this document與視頻幀的最大和最小持續時間的屬性和方法：

• supportsVideoMaxFrameDuration
• supportsVideoMinFrameDuration
• videoMaxFrameDuration
• videoMinFrameDuration

都被廢棄了。有替代品嗎？

Answer 1

根據頭文件（AVCaptureSession.h）

此屬性已被棄用iOS上，其中最小和最大幀速率調整是 使用 activeVideoMinFrameDuration和activeVideoMaxFrameDuration 屬性只施加在AVCaptureDevice 。

Answer 2

在iOS7

使用下列順序我讓它運行在我指定的幀速率（我也有使用activeVideoMinFrameDuration了一些問題，但是這似乎是一個有效的解決方案）：

AVCaptureDevice* camera = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo]; 
if([camera isTorchModeSupported:AVCaptureTorchModeOn]) { 
    [camera lockForConfiguration:nil]; 
    //configure frame rate 
    [camera setActiveVideoMaxFrameDuration:CMTimeMake(1, samplingFrequency)]; 
    [camera setActiveVideoMinFrameDuration:CMTimeMake(1, samplingFrequency)]; 
    [camera unlockForConfiguration]; 
} 

AVCaptureInput* cameraInput = [[AVCaptureDeviceInput alloc] initWithDevice:camera error:nil]; 
AVCaptureVideoDataOutput* videoOutput = [[AVCaptureVideoDataOutput alloc] init]; 
dispatch_queue_t captureQueue=dispatch_queue_create("catpureQueue", DISPATCH_QUEUE_SERIAL); 

//setup delegate 
[videoOutput setSampleBufferDelegate:self queue:captureQueue]; 

videoOutput.videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA], (id)kCVPixelBufferPixelFormatTypeKey, 
          nil]; 
[catpureSession setSessionPreset:AVCaptureSessionPresetMedium]; 

if([catpureSession canAddInput:cameraInput]) 
    [catpureSession addInput:cameraInput]; 
if([catpureSession canAddOutput:videoOutput]) 
    [catpureSession addOutput:videoOutput]; 

[catpureSession startRunning]; 

哪裏catpureSession是類的一個對象AVCaptureSession和samplingFrequency是我的幀速率（設定爲30）