多媒体编程ios摄像头图像抓取工具类

转载自  http://www.it165.net/pro/html/201408/19449.html

• 工具类提供预览图像画面，自动处理旋转，并且以主动方式抓取图像（这样帧率可以无限大）

  系统的接口多是异步接收图像，像我这种强迫症怎么受得了，必须吧被动接收图像的方式改成主动抓取。

  头文件

  view sourceprint?

  01.#import <Foundation/Foundation.h>

  02.#import <AVFoundation/AVFoundation.h>

  03. 

  04.//这些比例都是4：3的比例。

  05.typedef enum TKVideoFrameSize

  06.{

  07.tkVideoFrame480x360     = 480  << 16 | 360,

  08.tkVideoFrame720x540     = 720  << 16 | 540, //用这个分辨率，效率会快很多。

  09.}TKVideoFrameSize;

  10. 

  11. 

  12. 

  13.@interface TKVideoCapture : NSObject <AVCaptureVideoDataOutputSampleBufferDelegate>

  14. 

  15.- (bool) create:(UIView*)preview frame:(TKVideoFrameSize)type ;

  16.- (bool) destory;

  17. 

  18.- (bool) start ;

  19.- (bool) stop ;

  20. 

  21.//返回 字节顺序 BGRA BGRA 的图像数据。

  22.- (uint8_t*) get_image_rgb32:(uint32_t*)length ;

  23. 

  24.@end
  实现文件：（里面用到了那个Lock可以去上一篇文章找）
  view sourceprint?

  001.#import "TKVideoCapture.h"

  002.#import <UIKit/UIKit.h>

  003.#import <CoreGraphics/CoreGraphics.h>

  004.#import <CoreVideo/CoreVideo.h>

  005.#import <CoreMedia/CoreMedia.h>

  006.#import "TKLock.h"

  007. 

  008.@interface TKVideoCapture ()

  009.{

  010.TKVideoFrameSize            _frametype      ;

  011.UIView*                     _preview        ;

  012.AVCaptureSession*           _captureSession ;

  013.AVCaptureVideoPreviewLayer* _capturePreview ;

  014.AVCaptureVideoDataOutput *  _captureOutput  ;

  015.AVCaptureDevice*            _captureDevice  ;

  016.AVCaptureDeviceInput*       _captureInput   ;

  017. 

  018.uint8_t*                    _buffer_temp    ; //每一帧数据都存储到这个缓存中

  019.uint8_t*                    _buffer_obox    ; //需要使用时，从tempbuf 拷贝过来。

  020.CGRect                      _subImageRect   ; //子图片的位置。

  021. 

  022.TKLock*                     _buffer_lock    ;

  023.}

  024. 

  025.@end

  026. 

  027. 

  028.@implementation TKVideoCapture

  029. 

  030.- (void) do_create

  031.{

  032.self->_captureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo] ;

  033.self->_captureInput  = [AVCaptureDeviceInput deviceInputWithDevice:self->_captureDevice  error:nil];

  034.self->_captureOutput = [[AVCaptureVideoDataOutput alloc] init];

  035. 

  036.if(self->_captureOutput)

  037.[self->_captureOutput setAlwaysDiscardsLateVideoFrames:true];

  038. 

  039.dispatch_queue_t queue = dispatch_queue_create("cameraQueue", NULL);

  040.[self->_captureOutput setSampleBufferDelegate:self queue:queue];

  041. 

  042.dispatch_release(queue);

  043. 

  044. 

  045.NSString* key = (NSString*)kCVPixelBufferPixelFormatTypeKey;

  046.NSNumber* value = [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA];

  047. 

  048.NSDictionary* videoSettings = [NSDictionary dictionaryWithObject:value forKey:key];

  049. 

  050.[self->_captureOutput setVideoSettings:videoSettings];

  051.self->_captureSession = [[AVCaptureSession alloc] init];

  052. 

  053.uint16_t width  = (uint16_t)(((uint32_t)_frametype) >> 16) ;

  054.uint16_t height = (uint16_t)(((uint32_t)_frametype) & 0xFFFF) ;

  055. 

  056._buffer_temp = (uint8_t*)malloc(width * height * 4);

  057._buffer_obox = (uint8_t*)malloc(width * height * 4);

  058. 

  059.//0.75是预定比例

  060.switch (_frametype) {

  061.case tkVideoFrame480x360:

  062.{

  063._captureSession.sessionPreset = AVCaptureSessionPreset640x480 ;

  064._subImageRect = CGRectMake((640-360)/2, 0, 360, 480);

  065.break;

  066.}

  067.case tkVideoFrame720x540:

  068.{

  069._captureSession.sessionPreset = AVCaptureSessionPresetiFrame1280x720 ;

  070._subImageRect = CGRectMake((1280-540)/2, 0, 540, 720);

  071.break;

  072.}

  073.default:

  074.break;

  075.}

  076. 

  077.if(self->_captureInput != nil)

  078.[self->_captureSession addInput:self->_captureInput];

  079. 

  080.[self->_captureSession addOutput:self->_captureOutput];

  081. 

  082.self->_capturePreview = [AVCaptureVideoPreviewLayer layerWithSession: self->_captureSession];

  083.self->_capturePreview.frame = self->_preview.bounds;//CGRectMake(100, 0, 100, 100);

  084.self->_capturePreview.videoGravity = AVLayerVideoGravityResizeAspectFill;

  085.self->_capturePreview.connection.videoOrientation = [self getOrientation] ;

  086. 

  087.[self->_preview.layer addSublayer: self->_capturePreview];

  088. 

  089._buffer_lock = [[TKLock alloc] init];

  090.[_buffer_lock open];

  091.}

  092. 

  093.- (bool) create:(UIView*)preview frame:(TKVideoFrameSize)type

  094.{

  095.self->_frametype     = type ;

  096.self->_preview       = preview ;

  097. 

  098.[self performSelectorOnMainThread:@selector(do_create) withObject:self waitUntilDone:true];

  099. 

  100.return true ;

  101.}

  102. 

  103.- (AVCaptureVideoOrientation) getOrientation

  104.{

  105.UIInterfaceOrientation orientation = [UIApplication sharedApplication].statusBarOrientation ;

  106.switch(orientation)

  107.{

  108.case UIInterfaceOrientationPortrait: return AVCaptureVideoOrientationPortrait;

  109.case UIInterfaceOrientationPortraitUpsideDown: return AVCaptureVideoOrientationPortraitUpsideDown;

  110.case UIInterfaceOrientationLandscapeLeft: return AVCaptureVideoOrientationLandscapeLeft;

  111.case UIInterfaceOrientationLandscapeRight: return AVCaptureVideoOrientationLandscapeRight;

  112.}

  113.return AVCaptureVideoOrientationLandscapeLeft ;

  114.}

  115. 

  116.- (void) do_destory

  117.{

  118.[_buffer_lock close];

  119.[_buffer_lock release];

  120._buffer_lock = nil ;

  121. 

  122.free(_buffer_temp);

  123.free(_buffer_obox);

  124._buffer_temp = NULL ;

  125._buffer_obox = NULL ;

  126. 

  127.[self->_captureSession stopRunning];

  128.[self->_capturePreview removeFromSuperlayer];

  129.[self->_captureOutput  release];

  130.[self->_captureSession release];

  131.self->_captureSession = nil ;

  132.self->_capturePreview = nil ;

  133.self->_captureOutput  = nil ;

  134.self->_captureDevice  = nil ;

  135.self->_captureInput   = nil ;

  136.self->_preview        = nil ;

  137.}

  138. 

  139.- (bool) destory

  140.{

  141.[self performSelectorOnMainThread:@selector(do_destory) withObject:self waitUntilDone:true];

  142.return true ;

  143.}

  144. 

  145.- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection

  146.{

  147.CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);

  148.CVPixelBufferLockBaseAddress(imageBuffer,0);

  149.uint8_t* baseAddress = (uint8_t *)CVPixelBufferGetBaseAddress(imageBuffer);

  150. 

  151.size_t width  = CVPixelBufferGetWidth(imageBuffer);

  152.size_t height = CVPixelBufferGetHeight(imageBuffer);

  153.size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);

  154. 

  155.CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

  156.CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, baseAddress, bytesPerRow * height, NULL);

  157. 

  158.CGImageRef imageRef = CGImageCreate(width, height, 8, 32, bytesPerRow, colorSpace,

  159.kCGBitmapByteOrder32Little|kCGImageAlphaPremultipliedFirst,

  160.provider, NULL, false, kCGRenderingIntentDefault);

  161. 

  162.CGImageRef subImageRef = CGImageCreateWithImageInRect(imageRef, _subImageRect);

  163. 

  164.size_t subWidth  = _subImageRect.size.height ;

  165.size_t subHeight = _subImageRect.size.width  ;

  166. 

  167.CGContextRef context = CGBitmapContextCreate(NULL, subWidth, subHeight,

  168.CGImageGetBitsPerComponent(subImageRef), 0,

  169.CGImageGetColorSpace(subImageRef),

  170.CGImageGetBitmapInfo(subImageRef));

  171. 

  172. 

  173.CGContextTranslateCTM(context, 0, subHeight);

  174.CGContextRotateCTM(context, -M_PI/2);

  175. 

  176.CGContextDrawImage(context, CGRectMake(0, 0, subHeight, subWidth), subImageRef);

  177. 

  178.uint8_t* data = (uint8_t*)CGBitmapContextGetData(context);

  179. 

  180.[_buffer_lock lock];

  181.memcpy(_buffer_temp, data, subWidth * subHeight * 4);

  182.[_buffer_lock unlock];

  183. 

  184.CGContextRelease(context);

  185.CGImageRelease(imageRef);

  186.CGImageRelease(subImageRef);

  187.CGDataProviderRelease(provider);

  188.CGColorSpaceRelease(colorSpace);

  189.CVPixelBufferUnlockBaseAddress(imageBuffer,0);

  190.}

  191. 

  192.- (void) do_start

  193.{

  194.[self->_captureSession startRunning];

  195.}

  196. 

  197.- (void) do_stop

  198.{

  199.[self->_captureSession stopRunning];

  200.}

  201. 

  202.- (bool) start

  203.{

  204.[self performSelectorOnMainThread:@selector(do_start) withObject:self waitUntilDone:true];

  205.return true ;

  206.}

  207.- (bool) stop

  208.{

  209.[self performSelectorOnMainThread:@selector(do_stop) withObject:self waitUntilDone:true];

  210.return true ;

  211.}

  212. 

  213.- (uint8_t*) get_image_rgb32:(uint32_t*)length

  214.{

  215.uint16_t width  = (uint16_t)(((uint32_t)_frametype) >> 16) ;

  216.uint16_t height = (uint16_t)(((uint32_t)_frametype) & 0xFFFF) ;

  217. 

  218.//从摄像头输出数据采集数据

  219.[_buffer_lock lock];

  220.memcpy(_buffer_obox, _buffer_temp, width * height * 4);

  221.[_buffer_lock unlock];

  222. 

  223.if(length)

  224.*length = width * height * 4 ;

  225. 

  226.return _buffer_obox ;

  227.}

  228. 

  229. 

  230.@end

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