问题
In an app that I'm developing I'd like to let the user choose the the resolution of video recording. Due to specification, I can't use AVCaptureSessionPreset constants.
Getting format list there are resolutions above 3000px that of course can't work for video grabbing but only for photo shooting.
AVCaptureDeviceFormat: 0x17020c830 'vide'/'420f' 3264x2448, { 2- 30 fps}, HRSI:3264x2448, fov:58.040, max zoom:153.00 (upscales @1.00), AF System:2, ISO:29.0-1856.0, SS:0.000013-0.500000
I can't find a way to see if a specific format is suitable for video recording.
The problem is that with this kind of resolution if I try to grab a video the app generates an exception saying that there is no active or enabled connection.
-[AVCaptureMovieFileOutput startRecordingToOutputFileURL:recordingDelegate:] - no active/enabled connections.
I also don't want to hardcode limits for each kind of device.
I can't also try to cap the limit to AVCaptureSessionPresetHigh because as stated in an Apple note is not the actual maximum format.
Is there a way to understand if a AVCaptureDeviceFormat is suitable for grabbing video?
回答1:
After setting all the connections with the selected -activeFormat check if the current AVCaptureConnection isActive or observe using KVO the property -active. If it is no the format is not available for video grabbing, if it is yes it can be used.
来源：https://stackoverflow.com/questions/29730957/understand-if-an-avcapturedeviceformat-suits-video-recording