AvFundaction Capture Note

一、錄影的前置設定

1. 建立AVCaptureInput:AVCaptrueDeviceInput
2. 建立AVCaptureOutput:AVCaptureStillImageOutput、AVCaptureMovieFileOutput
3. 建立session:AVCaptrueSessuon
4. 串連input、output與session
5. 建立AVCaptureVideoPreviewLayer，並與session串聯
6. 將AVCaptureVideoPreviewLayer加到要預覽的view裡面的layer
7. 透過[session startRunning]，將預覽畫面顯示到previewLayer上
8. 錄影的前置設定完成

二、錄影進行

1. connection是input、output與session之間的橋梁，先取得介於output與session之間的connection，並設定錄影水平方向
2. 執行AVCaptureOutput的startRecordingToOutputFileURL:recordingDelegate:
3. AVCaptureOutput 的isRecording會變成YES

三、錄影結束

1. AVCaptureOutputinstance的AVCaptureOutput

其他附註
取得所有裝置

NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];

過濾出所要的裝置

    
NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
for (AVCaptureDevice *device in devices) {
    if ([device position] == position) {
    return device;
    }
}
return nil;

取得裝置清單

NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
- (AVCaptureDevice *) cameraWithPosition:(AVCaptureDevicePosition) position
{
    NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
    for (AVCaptureDevice *device in devices) {
        if ([device position] == position) {
            return device;
        }
    }
    return nil;
}

Torch mode

Torch mode is where a camera uses the flash continuously at a low power to illuminate a video capture. There are three torch modes:

• AVCaptureTorchModeOff: the torch is always off.
• AVCaptureTorchModeOn: the torch is always on.
• AVCaptureTorchModeAuto: the torch is switched on and off as needed.

You use hasTorch to determine whether a device has a flash. You use the isTorchModeSupported: method to determine whether a device supports a given flash mode, then set the mode using the torchMode property.

For devices with a torch, the torch only turns on if the device is associated with a running capture session.

取得音源裝置
NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeAudio];