AVController.h

#import <UIKit/UIKit.h>
#import <AVFoundation/AVFoundation.h>
#import <CoreGraphics/CoreGraphics.h>
#import <CoreVideo/CoreVideo.h>
#import <CoreMedia/CoreMedia.h>

/*!
	@class	AVController 
	@author Benjamin Loulier

	@brief    Controller to demonstrate how we can have a direct access to the camera using the iPhone SDK 4
*/
@interface AVController : UIViewController <AVCaptureVideoDataOutputSampleBufferDelegate> {
	AVCaptureSession *_captureSession;
	UIImageView *_imageView;
	CALayer *_customLayer;
	AVCaptureVideoPreviewLayer *_prevLayer;
}

/*!
 @brief	The capture session takes the input from the camera and capture it
 */
@property (nonatomic, retain) AVCaptureSession *captureSession;

/*!
 @brief	The UIImageView we use to display the image generated from the imageBuffer
 */
@property (nonatomic, retain) UIImageView *imageView;
/*!
 @brief	The CALayer we use to display the CGImageRef generated from the imageBuffer
 */
@property (nonatomic, retain) CALayer *customLayer;
/*!
 @brief	The CALAyer customized by apple to display the video corresponding to a capture session
 */
@property (nonatomic, retain) AVCaptureVideoPreviewLayer *prevLayer;

/*!
 @brief	This method initializes the capture session
 */
- (void)initCapture;

@end

AVController.m

#import "AVController.h"


@implementation AVController

@synthesize captureSession = _captureSession;
@synthesize imageView = _imageView;
@synthesize customLayer = _customLayer;
@synthesize prevLayer = _prevLayer;

#pragma mark -
#pragma mark Initialization
- (id)init {
	self = [super init];
	if (self) {
		/*We initialize some variables (they might be not initialized depending on what is commented or not)*/
		self.imageView = nil;
		self.prevLayer = nil;
		self.customLayer = nil;
		/*We intialize the capture*/
		[self initCapture];
	}
	return self;
}

- (void)initCapture {
	/*We setup the input*/
	AVCaptureDeviceInput *captureInput = [AVCaptureDeviceInput 
										  deviceInputWithDevice:[AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo] 
										  error:nil];
	/*We setupt the output*/
	AVCaptureVideoDataOutput *captureOutput = [[AVCaptureVideoDataOutput alloc] init]; 
	captureOutput.alwaysDiscardsLateVideoFrames = YES; 
	//captureOutput.minFrameDuration = CMTimeMake(1, 10); Uncomment it to specify a minimum duration for each video frame
	[captureOutput setSampleBufferDelegate:self queue:dispatch_get_main_queue()];
	// Set the video output to store frame in BGRA (It is supposed to be faster)
	NSString* key = (NSString*)kCVPixelBufferPixelFormatTypeKey; 
	NSNumber* value = [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA]; 
	NSDictionary* videoSettings = [NSDictionary dictionaryWithObject:value forKey:key]; 
	[captureOutput setVideoSettings:videoSettings]; 
	/*And we create a capture session*/
	self.captureSession = [[AVCaptureSession alloc] init];
	/*We add input and output*/
	[self.captureSession addInput:captureInput];
	[self.captureSession addOutput:captureOutput];
	/*We start the capture*/
	[self.captureSession startRunning];
	/*We add the preview layer*/
	/*self.prevLayer = [AVCaptureVideoPreviewLayer layerWithSession: self.captureSession];
	self.prevLayer.frame = self.view.bounds;
	self.prevLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
	[self.view.layer addSublayer: self.prevLayer];*/
	/*We add the Custom Layer (We need to change the orientation of the layer so that the video is displayed correctly)*/
	/*self.customLayer = [CALayer layer];
	self.customLayer.frame = self.view.bounds;
	self.customLayer.transform = CATransform3DRotate(CATransform3DIdentity, M_PI/2.0f, 0, 0, 1);
	self.customLayer.contentsGravity = kCAGravityResizeAspectFill;
	[self.view.layer addSublayer:self.customLayer];*/
	/*We add the imageView*/
	self.imageView = [[UIImageView alloc] initWithFrame:self.view.bounds];
	[self.view addSubview:self.imageView];
	
}

#pragma mark -
#pragma mark AVCaptureSession delegate
- (void)captureOutput:(AVCaptureOutput *)captureOutput 
didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer 
	   fromConnection:(AVCaptureConnection *)connection 
{ 
    CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer); 
    /*Lock the image buffer*/
    CVPixelBufferLockBaseAddress(imageBuffer,0); 
    /*Get information about the image*/
    uint8_t *baseAddress = (uint8_t *)CVPixelBufferGetBaseAddress(imageBuffer); 
    size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer); 
    size_t width = CVPixelBufferGetWidth(imageBuffer); 
    size_t height = CVPixelBufferGetHeight(imageBuffer); 
    
    /*Create a CGImageRef from the CVImageBufferRef*/
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); 
    CGContextRef newContext = CGBitmapContextCreate(baseAddress, width, height, 8, bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst); 
    CGImageRef newImage = CGBitmapContextCreateImage(newContext); 
	/*We unlock the  image buffer*/
	CVPixelBufferUnlockBaseAddress(imageBuffer,0);
	
    /*We release some components*/
    CGContextRelease(newContext); 
    CGColorSpaceRelease(colorSpace);
    
    /*We display the result on the custom layer*/
	/*self.customLayer.contents = (id) newImage;*/
	
	/*We display the result on the image view (We need to change the orientation of the image so that the video is displayed correctly)*/
	UIImage *image= [UIImage imageWithCGImage:newImage scale:1.0 orientation:UIImageOrientationRight];
	self.imageView.image = image;

	/*We relase the CGImageRef*/
	CGImageRelease(newImage);
} 

#pragma mark -
#pragma mark Memory management

- (void)viewDidUnload {
	self.imageView = nil;
	self.customLayer = nil;
	self.prevLayer = nil;
}

- (void)dealloc {
	[self.captureSession release];
    [super dealloc];
}


@end