AVCaptureSession指定obj-c iphone应用程序捕获图像的分辨率和质量
您好,我想设置AVCaptureSession指定obj-c iphone应用程序捕获图像的分辨率和质量,iphone,objective-c,avcapturesession,avcapture,Iphone,Objective C,Avcapturesession,Avcapture,您好,我想设置AVcapture会话,使用iphone摄像头以特定分辨率(如果可能的话,以特定质量)拍摄图像。这里是设置AV会话代码 // Create and configure a capture session and start it running - (void)setupCaptureSession { NSError *error = nil; // Create the session self.captureSession = [[AVCaptur
AV
capture会话,使用iphone摄像头以特定分辨率(如果可能的话,以特定质量)拍摄图像。这里是设置AV
会话代码
// Create and configure a capture session and start it running
- (void)setupCaptureSession
{
NSError *error = nil;
// Create the session
self.captureSession = [[AVCaptureSession alloc] init];
// Configure the session to produce lower resolution video frames, if your
// processing algorithm can cope. We'll specify medium quality for the
// chosen device.
captureSession.sessionPreset = AVCaptureSessionPresetMedium;
// Find a suitable AVCaptureDevice
NSArray *cameras=[AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
AVCaptureDevice *device;
if ([UserDefaults camera]==UIImagePickerControllerCameraDeviceFront)
{
device =[cameras objectAtIndex:1];
}
else
{
device = [cameras objectAtIndex:0];
};
// Create a device input with the device and add it to the session.
AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];
if (!input)
{
NSLog(@"PANIC: no media input");
}
[captureSession addInput:input];
// Create a VideoDataOutput and add it to the session
AVCaptureVideoDataOutput *output = [[AVCaptureVideoDataOutput alloc] init];
[captureSession addOutput:output];
NSLog(@"connections: %@", output.connections);
// Configure your output.
dispatch_queue_t queue = dispatch_queue_create("myQueue", NULL);
[output setSampleBufferDelegate:self queue:queue];
dispatch_release(queue);
// Specify the pixel format
output.videoSettings = [NSDictionary dictionaryWithObject:[NSNumber numberWithInt:kCVPixelFormatType_32BGRA] forKey:(id)kCVPixelBufferPixelFormatTypeKey];
// If you wish to cap the frame rate to a known value, such as 15 fps, set
// minFrameDuration.
// Assign session to an ivar.
[self setSession:captureSession];
[self.captureSession startRunning];
}
和setSession
:
-(void)setSession:(AVCaptureSession *)session
{
NSLog(@"setting session...");
self.captureSession=session;
NSLog(@"setting camera view");
self.previewLayer = [AVCaptureVideoPreviewLayer layerWithSession:session];
//UIView *aView = self.view;
CGRect videoRect = CGRectMake(20.0, 20.0, 280.0, 255.0);
previewLayer.frame = videoRect; // Assume you want the preview layer to fill the view.
[previewLayer setBackgroundColor:[[UIColor grayColor] CGColor]];
[self.view.layer addSublayer:previewLayer];
//[aView.layer addSublayer:previewLayer];
}
和输出方法:
// Delegate routine that is called when a sample buffer was written
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
fromConnection:(AVCaptureConnection *)connection
{
//NSLog(@"captureOutput: didOutputSampleBufferFromConnection");
// Create a UIImage from the sample buffer data
self.currentImage = [self imageFromSampleBuffer:sampleBuffer];
//< Add your code here that uses the image >
}
// Create a UIImage from sample buffer data
- (UIImage *) imageFromSampleBuffer:(CMSampleBufferRef) sampleBuffer
{
//NSLog(@"imageFromSampleBuffer: called");
// 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);
// Create an image object from the Quartz image
UIImage *image = [UIImage imageWithCGImage:quartzImage];
// Release the Quartz image
CGImageRelease(quartzImage);
return (image);
}
//在写入示例缓冲区时调用的委托例程
-(void)captureOutput:(AVCaptureOutput*)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
fromConnection:(AVCaptureConnection*)连接
{
//NSLog(@“captureOutput:didOutputSampleBufferFromConnection”);
//从样本缓冲区数据创建UIImage
self.currentImage=[self-imageFromSampleBuffer:sampleBuffer];
//<在此处添加使用图像的代码>
}
//从样本缓冲区数据创建UIImage
-(UIImage*)imageFromSampleBuffer:(CMSampleBufferRef)sampleBuffer
{
//NSLog(@“imageFromSampleBuffer:调用”);
//为媒体数据获取CMSampleBuffer的核心视频图像缓冲区
CVImageBufferRef imageBuffer=CMSampleBufferGetImageBuffer(sampleBuffer);
//锁定像素缓冲区的基址
CVPixelBufferLockBaseAddress(imageBuffer,0);
//获取像素缓冲区的每行字节数
void*baseAddress=CVPixelBufferGetBaseAddress(imageBuffer);
//获取像素缓冲区的每行字节数
size_t bytesPerRow=CVPixelBufferGetBytesPerRow(图像缓冲区);
//获取像素缓冲区的宽度和高度
size\u t width=CVPixelBufferGetWidth(imageBuffer);
大小\u t高度=CVPixelBufferGetHeight(imageBuffer);
//创建设备相关的RGB颜色空间
CGColorSpaceRef colorSpace=CGColorSpaceCreateDeviceRGB();
//使用示例缓冲区数据创建位图图形上下文
CGContextRef context=CGBitmapContextCreate(基地址、宽度、高度、8、字节数、颜色空间、kCGBitmapByteOrder32Little | KCGimageAlphaPremultipledFirst);
//从位图图形上下文中的像素数据创建石英图像
CGImageRef quartzImage=CGBitmapContextCreateImage(上下文);
//解锁像素缓冲区
CVPixelBufferUnlockBaseAddress(imageBuffer,0);
//释放上下文和颜色空间
CGContextRelease(上下文);
CGCOLORSPACTERELEASE(色彩空间);
//从石英图像创建图像对象
UIImage*image=[UIImage imageWithCGImage:quartzImage];
//释放石英图像
CGImageRelease(四倍图像);
返回(图像);
}
一切都很标准。但是我应该在哪里改变,改变什么来指定捕获图像的分辨率和质量。请帮助我请参阅“拍摄静止图像”部分,了解如果设置一个或另一个预设,将获得的尺寸
您应该更改的参数是captureSession.sessionPreset尝试使用类似的方法,其中cx和cy是您的自定义分辨率:
NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
AVVideoScalingModeResizeAspectFill,AVVideoScalingModeKey,
AVVideoCodecH264, AVVideoCodecKey,
[NSNumber numberWithInt:cx], AVVideoWidthKey,
[NSNumber numberWithInt:cx], AVVideoHeightKey,
nil];
_videoInput = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo outputSettings:videoSettings];
我的应用程序中有一个
UISlider
,使用它的用户将指定他想要的更高或更低的值。但哪些值更高?NSString*const AVCaptureSessionPresetPhoto;NSString*常量AVCaptureSessionPresetHigh;NSString*const AVCaptureSessionPresetMedium;NSString*常量AVCaptureSessionPresetLow;NSString*常量AVCaptureSessionPreset320x240;NSString*const AVCaptureSessionPreset352x288;NSString*常量AVCaptureSessionPreset640x480;NSString*const AVCaptureSessionPreset960x540;NSString*const AVCaptureSessionPreset1280x720代码>很明显,质量好的更高。。这可能会有帮助。