Taking high resolution photo from captureStillImageAsynchronouslyFromConnection

Question

Currently captureStillImageAsynchronouslyFromConnection returns an image at 640x480 pixels from a AVCaptureSession of AVCaptureSessionPreset640x480.

The reason for a relative low-res AVCaptureSessionPreset640x480 is I need to process the video frames. Lower resolution gives better speed.

At certain point, when I want to take a photo, I want a hi-res image. How can I tell captureStillImageAsynchronouslyFromConnection to return a higher than 640x480 image?

Answer 1

You tell captureStillImageAsynchronouslyFromConnection to return a higher-resolution image by setting a higher-resolution preset.

Since 4.2, AVCaptureVideoDataOutput will return approximately screen-sized video frames for AVCaptureSessionPresetPhoto, which it sounds like would be ideal for your purposes. OTOH, in 4.1 and earlier it will return nothing. If you have to target 4.1 and earlier, you'll have to take the very slow way of changing the preset before capturing.