通過AVFoundation框架獲取攝像頭數據

2019-11-09 15:02:26

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一、概述從iOS4開始，AVFoundation框架增加了幾個類，AVCaptureDevice、AVCapturesession等，可以獲取攝像頭的數據，而不會彈出類似于ImagePicker一樣的界面，我們可以將數據轉為一張張的圖片，然后我們可以即時顯示在視圖上，也可以使用FFMPEG或者其它的視頻編碼工具，來合成視頻。二、步驟第一步：創(chuàng)建AVCaptureSession，添加輸入，輸出源#import <AVFoundation/AVFoundation.h>//創(chuàng)建并配置一個攝像會話，并啟動。- (void)setupCaptureSession{ NSError *error = nil; //創(chuàng)建會話 AVCaptureSession *session = [[AVCaptureSession alloc] init]; //設置視頻質量 session.sessionPReset = AVCaptureSessionPresetMedium; //獲取合適的AVCaptureDevice AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo]; //創(chuàng)建設備輸入流，并增加到會話。 AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error]; if (!input) { //處理錯誤 } [session addInput:input]; //創(chuàng)建一個視頻輸出流，并增加到會話。 AVCaptureVideoDataOutput *output = [[[AVCaptureVideoDataOutput alloc] init] autorelease]; [session addOutput:output]; //配置輸出流 dispatch_queue_t queue = dispatch_queue_create("myQueue", NULL); [output setSampleBufferDelegate:self queue:queue]; dispatch_release(queue); //指定像素格式。 output.videoSettings = [NSDictionary dictionaryWithObject: [NSNumber numberWithInt:kCVPixelFormatType_32BGRA] forKey:(id)kCVPixelBufferPixelFormatTypeKey]; //設置FPS output.minFrameDuration = CMTimeMake(1, 15); //啟動會話 [session startRunning]; //將會話與當前控制器關聯 [self setSession:session];}第二步：實現AVCaptureVideoDataOutputSampleBufferDelegate協議方法 //當采樣數據被寫入緩沖區(qū)時調用- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection{ //抽取采樣數據，合成UIImage對象 UIImage *image = [self imageFromSampleBuffer:sampleBuffer]; //后續(xù)自定義處理 xxxxxxxx}//抽取采樣數據，合成UIImage對象- (UIImage *)imageFromSampleBuffer:(CMSampleBufferRef) sampleBuffer{ CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer); //鎖定像素緩沖區(qū)的起始地址 CVPixelBufferLockBaseAddress(imageBuffer,0); //獲取每行像素的字節(jié)數 size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer); //獲取像素緩沖區(qū)的寬度和高度 size_t width = CVPixelBufferGetWidth(imageBuffer); size_t height = CVPixelBufferGetHeight(imageBuffer); //創(chuàng)建基于設備的RGB顏色空間 CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); if (!colorSpace) { NSLog(@"CGColorSpaceCreateDeviceRGB failure"); return nil; } //獲取像素緩沖區(qū)的起始地址 void *baseAddress = CVPixelBufferGetBaseAddress(imageBuffer); //獲取像素緩沖區(qū)的數據大小 size_t bufferSize = CVPixelBufferGetDataSize(imageBuffer); //使用提供的數據創(chuàng)建CGDataProviderRef CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, baseAddress, bufferSize,NULL); //通過CGDataProviderRef，創(chuàng)建CGImageRef CGImageRef cgImage = CGImageCreate(width, height, 8, 32, bytesPerRow, colorSpace, kCGImageAlphaNoneSkipFirst | kCGBitmapByteOrder32Little, provider, NULL, true, kCGRenderingIntentDefault); CGDataProviderRelease(provider); CGColorSpaceRelease(colorSpace); //創(chuàng)建UIImage UIImage *image = [UIImage imageWithCGImage:cgImage]; CGImageRelease(cgImage); //解鎖像素緩沖區(qū)起始地址 CVPixelBufferUnlockBaseAddress(imageBuffer, 0); return image;}

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