多媒體編程——ios網路攝影機映像抓取工具類

多媒體編程——ios網路攝影機映像抓取工具類

工具類提供預覽映像畫面，自動處理旋轉，並且以主動方式抓取映像（這樣幀率可以無限大）

系統的介面多是非同步接收映像，像我這種強迫症怎麼受得了，必須吧被動接收映像的方式改成主動抓取。

標頭檔

#import #import //這些比例都是4：3的比例。typedef enum TKVideoFrameSize{    tkVideoFrame480x360     = 480  << 16 | 360,    tkVideoFrame720x540     = 720  << 16 | 540, //用這個解析度，效率會快很多。}TKVideoFrameSize;@interface TKVideoCapture : NSObject - (bool) create:(UIView*)preview frame:(TKVideoFrameSize)type ;- (bool) destory;- (bool) start ;- (bool) stop ;//返回 位元組順序 BGRA BGRA 的映像資料。- (uint8_t*) get_image_rgb32:(uint32_t*)length ;@end

實現檔案：（裡面用到了那個Lock可以去上一篇文章找）

#import "TKVideoCapture.h"#import #import #import #import #import "TKLock.h"@interface TKVideoCapture (){    TKVideoFrameSize            _frametype      ;    UIView*                     _preview        ;    AVCaptureSession*           _captureSession ;    AVCaptureVideoPreviewLayer* _capturePreview ;    AVCaptureVideoDataOutput *  _captureOutput  ;    AVCaptureDevice*            _captureDevice  ;    AVCaptureDeviceInput*       _captureInput   ;        uint8_t*                    _buffer_temp    ; //每一幀資料都儲存到這個緩衝中    uint8_t*                    _buffer_obox    ; //需要使用時，從tempbuf 拷貝過來。    CGRect                      _subImageRect   ; //子圖片的位置。        TKLock*                     _buffer_lock    ;}@end@implementation TKVideoCapture- (void) do_create{    self->_captureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo] ;    self->_captureInput  = [AVCaptureDeviceInput deviceInputWithDevice:self->_captureDevice  error:nil];    self->_captureOutput = [[AVCaptureVideoDataOutput alloc] init];        if(self->_captureOutput)        [self->_captureOutput setAlwaysDiscardsLateVideoFrames:true];        dispatch_queue_t queue = dispatch_queue_create("cameraQueue", NULL);    [self->_captureOutput setSampleBufferDelegate:self queue:queue];        dispatch_release(queue);            NSString* key = (NSString*)kCVPixelBufferPixelFormatTypeKey;    NSNumber* value = [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA];        NSDictionary* videoSettings = [NSDictionary dictionaryWithObject:value forKey:key];        [self->_captureOutput setVideoSettings:videoSettings];    self->_captureSession = [[AVCaptureSession alloc] init];        uint16_t width  = (uint16_t)(((uint32_t)_frametype) >> 16) ;    uint16_t height = (uint16_t)(((uint32_t)_frametype) & 0xFFFF) ;        _buffer_temp = (uint8_t*)malloc(width * height * 4);    _buffer_obox = (uint8_t*)malloc(width * height * 4);        //0.75是預定比例    switch (_frametype) {        case tkVideoFrame480x360:        {            _captureSession.sessionPreset = AVCaptureSessionPreset640x480 ;            _subImageRect = CGRectMake((640-360)/2, 0, 360, 480);            break;        }        case tkVideoFrame720x540:        {            _captureSession.sessionPreset = AVCaptureSessionPresetiFrame1280x720 ;            _subImageRect = CGRectMake((1280-540)/2, 0, 540, 720);            break;        }        default:            break;    }        if(self->_captureInput != nil)        [self->_captureSession addInput:self->_captureInput];        [self->_captureSession addOutput:self->_captureOutput];        self->_capturePreview = [AVCaptureVideoPreviewLayer layerWithSession: self->_captureSession];    self->_capturePreview.frame = self->_preview.bounds;//CGRectMake(100, 0, 100, 100);    self->_capturePreview.videoGravity = AVLayerVideoGravityResizeAspectFill;    self->_capturePreview.connection.videoOrientation = [self getOrientation] ;        [self->_preview.layer addSublayer: self->_capturePreview];        _buffer_lock = [[TKLock alloc] init];    [_buffer_lock open];}- (bool) create:(UIView*)preview frame:(TKVideoFrameSize)type{    self->_frametype     = type ;    self->_preview       = preview ;        [self performSelectorOnMainThread:@selector(do_create) withObject:self waitUntilDone:true];        return true ;}- (AVCaptureVideoOrientation) getOrientation{    UIInterfaceOrientation orientation = [UIApplication sharedApplication].statusBarOrientation ;    switch(orientation)    {        case UIInterfaceOrientationPortrait: return AVCaptureVideoOrientationPortrait;        case UIInterfaceOrientationPortraitUpsideDown: return AVCaptureVideoOrientationPortraitUpsideDown;        case UIInterfaceOrientationLandscapeLeft: return AVCaptureVideoOrientationLandscapeLeft;        case UIInterfaceOrientationLandscapeRight: return AVCaptureVideoOrientationLandscapeRight;    }    return AVCaptureVideoOrientationLandscapeLeft ;}- (void) do_destory{    [_buffer_lock close];    [_buffer_lock release];    _buffer_lock = nil ;        free(_buffer_temp);    free(_buffer_obox);    _buffer_temp = NULL ;    _buffer_obox = NULL ;        [self->_captureSession stopRunning];    [self->_capturePreview removeFromSuperlayer];    [self->_captureOutput  release];    [self->_captureSession release];    self->_captureSession = nil ;    self->_capturePreview = nil ;    self->_captureOutput  = nil ;    self->_captureDevice  = nil ;    self->_captureInput   = nil ;    self->_preview        = nil ;}- (bool) destory{    [self performSelectorOnMainThread:@selector(do_destory) withObject:self waitUntilDone:true];    return true ;}- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection{    CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);    CVPixelBufferLockBaseAddress(imageBuffer,0);    uint8_t* baseAddress = (uint8_t *)CVPixelBufferGetBaseAddress(imageBuffer);        size_t width  = CVPixelBufferGetWidth(imageBuffer);    size_t height = CVPixelBufferGetHeight(imageBuffer);    size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);        CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();    CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, baseAddress, bytesPerRow * height, NULL);        CGImageRef imageRef = CGImageCreate(width, height, 8, 32, bytesPerRow, colorSpace,                                        kCGBitmapByteOrder32Little|kCGImageAlphaPremultipliedFirst,                                        provider, NULL, false, kCGRenderingIntentDefault);        CGImageRef subImageRef = CGImageCreateWithImageInRect(imageRef, _subImageRect);        size_t subWidth  = _subImageRect.size.height ;    size_t subHeight = _subImageRect.size.width  ;        CGContextRef context = CGBitmapContextCreate(NULL, subWidth, subHeight,                                  CGImageGetBitsPerComponent(subImageRef), 0,                                  CGImageGetColorSpace(subImageRef),                                  CGImageGetBitmapInfo(subImageRef));        CGContextTranslateCTM(context, 0, subHeight);    CGContextRotateCTM(context, -M_PI/2);    CGContextDrawImage(context, CGRectMake(0, 0, subHeight, subWidth), subImageRef);    uint8_t* data = (uint8_t*)CGBitmapContextGetData(context);        [_buffer_lock lock];    memcpy(_buffer_temp, data, subWidth * subHeight * 4);    [_buffer_lock unlock];        CGContextRelease(context);    CGImageRelease(imageRef);    CGImageRelease(subImageRef);    CGDataProviderRelease(provider);    CGColorSpaceRelease(colorSpace);    CVPixelBufferUnlockBaseAddress(imageBuffer,0);}- (void) do_start{    [self->_captureSession startRunning];}- (void) do_stop{    [self->_captureSession stopRunning];}- (bool) start{    [self performSelectorOnMainThread:@selector(do_start) withObject:self waitUntilDone:true];    return true ;}- (bool) stop{    [self performSelectorOnMainThread:@selector(do_stop) withObject:self waitUntilDone:true];    return true ;}- (uint8_t*) get_image_rgb32:(uint32_t*)length{    uint16_t width  = (uint16_t)(((uint32_t)_frametype) >> 16) ;    uint16_t height = (uint16_t)(((uint32_t)_frametype) & 0xFFFF) ;        //從網路攝影機輸出資料擷取資料    [_buffer_lock lock];    memcpy(_buffer_obox, _buffer_temp, width * height * 4);    [_buffer_lock unlock];        if(length)        *length = width * height * 4 ;        return _buffer_obox ;}@end