cocoa-touch - iOS8视频尺寸，CMVideoDimensions返回0,0

Question

在 iOS8 中返回的维度是 0,0

CMVideoDimensions dimensions = CMVideoFormatDescriptionGetDimensions(formatDescription);

这是在 iOS7 上工作的，所以如何知道支持的视频尺寸，因为我需要知道视频宽高比

Answer 1

您需要等待AVCaptureInputPortFormatDescriptionDidChangeNotification

- (void)avCaptureInputPortFormatDescriptionDidChangeNotification:(NSNotification *)notification {

    AVCaptureInput *input = [self.recorder.captureSession.inputs objectAtIndex:0];
    AVCaptureInputPort *port = [input.ports objectAtIndex:0];
    CMFormatDescriptionRef formatDescription = port.formatDescription;
    if (formatDescription) {
        CMVideoDimensions dimensions = CMVideoFormatDescriptionGetDimensions(formatDescription);
        if ((dimensions.width == 0) || (dimensions.height == 0)) {
            return;
        }
        CGFloat aspect = (CGFloat)dimensions.width / (CGFloat)dimensions.height;

        if (floor(NSFoundationVersionNumber) > NSFoundationVersionNumber_iOS_7_1) {
            // since iOS8 the aspect ratio is inverted
            // remove this check if iOS7 will not be supported
            aspect = 1.f / aspect;
        }

    }

}