captureStillImageAsynchronouslyFromConnection没有JPG中介 [英] captureStillImageAsynchronouslyFromConnection without JPG intermediary

问题描述

我正试图从相机中获得尽可能好的图像，但只能找到 captureStillImageAsynchronouslyFromConnection 的示例，然后直接进入：

I'm trying to get as good an image as possible from the camera, but can only find examples that captureStillImageAsynchronouslyFromConnection and then go straight to:

NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageSampleBuffer];    
UIImage *image = [[UIImage alloc] initWithData:imageData];

JPEG有损并且全部，有没有办法将数据作为PNG，甚至只是RGBA （BGRA，你有什么？）。 AVCaptureStillImageOutput似乎没有任何其他NSData *方法....

JPEG being lossy and all, is there any way to get the data as PNG, or even just RGBA (BGRA, what-have-you?). AVCaptureStillImageOutput doesn't seem to have any other NSData* methods....

实际上看看CMSampleBufferRef，好像已经锁定为JPEG~

Actually looking at the CMSampleBufferRef, it seems like it's already locked as JPEG ~

formatDescription = <CMVideoFormatDescription 0xfe5e1f0 [0x3e5ac650]> {
mediaType:'vide' 
mediaSubType:'jpeg' 
mediaSpecific: {
    codecType: 'jpeg'       dimensions: 2592 x 1936 
} 
extensions: {(null)}
}

还有其他方法可以采取全额措施res picture并获取原始数据？

Is there some other way to take a full-res picture and get the raw data?

推荐答案

您需要使用不同的像素格式设置outputSettings。例如，如果你想要32位BGRA，你可以设置：

You'll need to set the outputSettings with a different pixel format. If you want 32-bit BGRA, for example, you can set:

NSDictionary *outputSettings = [NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA], (id)kCVPixelBufferPixelFormatTypeKey, nil];

来自 https://developer.apple.com/library/mac/#documentation/AVFoundation/Reference/AVCaptureStillImageOutput_Class/Reference/Reference.html ，推荐像素格式为：

From https://developer.apple.com/library/mac/#documentation/AVFoundation/Reference/AVCaptureStillImageOutput_Class/Reference/Reference.html, the "recommended" pixel formats are:

• kCMVideoCodecType_JPEG


• kCVPixelFormatType_420YpCbCr8BiPlanarFullRange


• kCVPixelFormatType_32BGRA

• kCMVideoCodecType_JPEG
• kCVPixelFormatType_420YpCbCr8BiPlanarFullRange
• kCVPixelFormatType_32BGRA

当然，如果您不使用JPEG输出，则不能使用 jpegStillImageNSDataRepresentation：，但这里有一个例子：
如何转换a CVImageBufferRef到UIImage

Of course, if you're not using JPEG output, you can't use jpegStillImageNSDataRepresentation:, but there's an example here: how to convert a CVImageBufferRef to UIImage

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