关于ios:iOS拍照定制之AVCaptureVideoDataOutput

领导看了后面做的拍照，问了句 ” 哪来的声音 ”,

“ 零碎的，自带的，你看零碎的拍照也有声音 ”

“ 有方法能去掉吗？挺糟心的 ”

“ 我试试 ”

路漫漫其修远兮，吾在度娘 +SDK 中求索

拍砖 AVCaptureVideoDataOutput, 代理办法中将 CMSampleBufferRef 转成 UIImage

上码

• session 设置不提
• layer 设置可参考上篇 [iOS 拍照定制之 AVCapturePhotoOutput] 以及 上上篇 [iOS 写在定制相机之前]
• 获取摄像头、取到设施输出增加到 session、初始化 videoOutput 增加入 session

AVCaptureDevice *device = [self cameraDevice];
if (!device) {NSLog(@"获得后置摄像头出问题");
    return;;
}

NSError *error = nil;
self.videoInput = [[AVCaptureDeviceInput alloc] initWithDevice:device error:nil];

// 设施增加到会话中
if ([self.captureSession canAddInput:self.videoInput]) {[self.captureSession addInput:self.videoInput];
}

[self.videoOutput setSampleBufferDelegate:self queue:self.videoQueue];
if ([self.captureSession canAddOutput:self.videoOutput]) {[self.captureSession addOutput:self.videoOutput];
}

// 懒加载
- (AVCaptureVideoDataOutput *)videoOutput {if (!_videoOutput) {_videoOutput = [[AVCaptureVideoDataOutput alloc] init];
        _videoOutput.alwaysDiscardsLateVideoFrames = YES;
        _videoOutput.videoSettings = [NSDictionary dictionaryWithObject:[NSNumber numberWithInt:kCVPixelFormatType_32BGRA]
                                                                 forKey:(id)kCVPixelBufferPixelFormatTypeKey];
    }
    return _videoOutput;
}

- (dispatch_queue_t)videoQueue {if (!_videoQueue) {_videoQueue = dispatch_queue_create("queue", DISPATCH_QUEUE_SERIAL);
    }
    return _videoQueue;
}

• 代理 AVCaptureVideoDataOutputSampleBufferDelegate

- (void)captureOutput:(AVCaptureOutput *)output didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {
    @autoreleasepool {if (connection == [self.videoOutput connectionWithMediaType:AVMediaTypeVideo]) { // 视频
            @synchronized (self) {UIImage *image = [self bufferToImage:sampleBuffer rect:self.scanView.scanRect];
                self.uploadImg = image;
            }
        }
    }
}

• CMSampleBufferRef 转成 UIImage, 该办法有所调整，截图整张图中的某一部分，按需设置。具体获取指定区域图片需本人调整

- (UIImage *)bufferToImage:(CMSampleBufferRef)sampleBuffer rect:(CGRect)rect {
    // Get a CMSampleBuffer's Core Video image buffer for the media data
    CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
    // Lock the base address of the pixel buffer
    CVPixelBufferLockBaseAddress(imageBuffer, 0);

    // Get the number of bytes per row for the pixel buffer
    void *baseAddress = CVPixelBufferGetBaseAddress(imageBuffer);

    // Get the number of bytes per row for the pixel buffer
    size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
    // Get the pixel buffer width and height
    size_t width = CVPixelBufferGetWidth(imageBuffer);
    size_t height = CVPixelBufferGetHeight(imageBuffer);

    // Create a device-dependent RGB color space
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

    // Create a bitmap graphics context with the sample buffer data
    CGContextRef context = CGBitmapContextCreate(baseAddress, width, height, 8,
                                                 bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);
    // Create a Quartz image from the pixel data in the bitmap graphics context
    CGImageRef quartzImage = CGBitmapContextCreateImage(context);
    // Unlock the pixel buffer
    CVPixelBufferUnlockBaseAddress(imageBuffer,0);

    // Free up the context and color space
    CGContextRelease(context);
    CGColorSpaceRelease(colorSpace);
    
    // 获取指定区域图片
    CGRect dRect;
    CGSize msize = UIScreen.mainScreen.bounds.size;
    msize.height = msize.height - 150;
    CGFloat x = width * rect.origin.x / msize.width;
    CGFloat y = height * rect.origin.y / msize.height;
    CGFloat w = width * rect.size.width / msize.width;
    CGFloat h = height * rect.size.height / msize.height;
    dRect = CGRectMake(x, y, w, h);
    
    CGImageRef partRef = CGImageCreateWithImageInRect(quartzImage, dRect);
    
    // Create an image object from the Quartz image
    UIImage *image = [UIImage imageWithCGImage:partRef];

    // Release the Quartz image
    CGImageRelease(partRef);
    CGImageRelease(quartzImage);
    
    return image;
}