Video freezes on camera switch with AVFoundation

Question

I made an app with a feature to capture and save video. I have used AVFoundation for that and Apple\'s AVCam has been my guide.

I hope I can make it clear:
Every

Answer 1

Are you getting error logs? If not, you need to fix the code above and see what they say. What version of AVCam are you using? They've recently updated the project to version 1.2, which is much more efficient and uses blocks.

From my experience, you shouldn't be creating and recreating a session, you can just leave it on. Maybe you need to structure your app a little differently. What exactly is your app about? Maybe we can help you. If your app is centred around the camera, then it's easier to leave the session on, if your just taking video modally, then maybe using AVCam is overkill.

Your actual problem, to me, sounds like it's with AVCaptureDeviceInput. Download the original AVCam package and see if you've changed any retain counts, or safety if statements. If there's any other code, please post.

UPDATE: Can you change

} else if (error) {
    NSLog(@"%@",[error localizedDescription]);
}

to

} if (error) {
    NSLog(@"%@",[error localizedDescription]);
}

and tell me if there's an error?

Also, before you release the view controller that owns the session, make sure you stop the session and set the capture manager to nil.

UPDATE 2: Try this toggle code. It's what I have been using. AVCamMirringMode is a struct as follows:

enum {
    AVCamMirroringOff   = 1,
    AVCamMirroringOn    = 2,
    AVCamMirroringAuto  = 3
};
typedef NSInteger AVCamMirroringMode;


- (BOOL) toggleCamera
{
    BOOL success = NO;

    if ([self cameraCount] > 1) {
        NSError *error;
        AVCaptureDeviceInput *newVideoInput;
        AVCaptureDevicePosition position = [[videoInput device] position];

        BOOL mirror;
        if (position == AVCaptureDevicePositionBack){
            newVideoInput = [[AVCaptureDeviceInput alloc] initWithDevice:[self frontFacingCamera] error:&error];
            switch ([self mirroringMode]) {
                case AVCamMirroringOff:
                    mirror = NO;
                    break;
                case AVCamMirroringOn:
                    mirror = YES;
                    break;
                case AVCamMirroringAuto:
                default:
                    mirror = YES;
                    break;
            }
        }
        else if (position == AVCaptureDevicePositionFront){
            newVideoInput = [[AVCaptureDeviceInput alloc] initWithDevice:[self backFacingCamera] error:&error];
            switch ([self mirroringMode]) {
                case AVCamMirroringOff:
                    mirror = NO;
                    break;
                case AVCamMirroringOn:
                    mirror = YES;
                    break;
                case AVCamMirroringAuto:
                default:
                    mirror = NO;
                    break;
            }
        }
        else
            goto bail;

        if (newVideoInput != nil) {
            [[self session] beginConfiguration];
            [[self session] removeInput:[self videoInput]];
            if ([[self session] canAddInput:newVideoInput]) {
                [[self session] addInput:newVideoInput];
                AVCaptureConnection *connection = [AVCamUtilities connectionWithMediaType:AVMediaTypeVideo fromConnections:[[self stillImageOutput] connections]];
                if ([connection isVideoMirroringSupported]) {
                    [connection setVideoMirrored:mirror];
                }
                [self setVideoInput:newVideoInput];
            } else {
                [[self session] addInput:[self videoInput]];
            }
            [[self session] commitConfiguration];
            success = YES;
            [newVideoInput release];

        } else if (error) {
            if ([[self delegate] respondsToSelector:@selector(captureManager:didFailWithError:)]) {
                [[self delegate] captureManager:self didFailWithError:error];
            }
        }
    }

bail:
    return success;
}

Answer 2

Try this—it worked like a champ for me:

BOOL isUsingFrontFacingCamera;

- (BOOL) swapCameras
{
    if ([self cameraCount] > 1) {
        AVCaptureDevicePosition desiredPosition;
        if (isUsingFrontFacingCamera) {
            desiredPosition = AVCaptureDevicePositionBack;
        } else {
            desiredPosition = AVCaptureDevicePositionFront;
        }

        for (AVCaptureDevice *d in [AVCaptureDevice devicesWithMediaType: AVMediaTypeVideo]) {
            if ([d position] == desiredPosition) {
                [[self session] beginConfiguration];
                AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:d error:nil];
                for (AVCaptureInput *oldInput in [[self session] inputs]) {
                    [[self session] removeInput:oldInput];
                }
                [[self session] addInput:input];
                [[self session] commitConfiguration];
                break;
            }
        }
        isUsingFrontFacingCamera = !isUsingFrontFacingCamera;
        return YES;
    }
    return NO;
}

You should be able to drop this code in to replace the original swapCameras in VideoRecorderCaptureManager.m

Origin: Apple's SquareCam sample code.