1.

    //设置CIContext,并从CIImage -> CGImage -> UIImage
CIContext *context = [CIContext contextWithOptions:nil];
CGImageRef cgImage = [context createCGImage: outputImage fromRect:qrRect];
UIImage *resultIamge = [UIImage imageWithCGImage:cgImage];
//(如果 直接用[UIImage imageWithCIImage:outputImage]; 会得到一个不是位图的图片)

还有一个,就是CIImage 只有经过context 转化为CGImage后,才能变成位图图片。(非位图图片,不能保存到相册,不能转换为NSData (jpeg png))

 
 
 2.
 
kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange = '420v',表示输出的视频格式为NV12;范围: (luma=[16,235] chroma=[16,240])
kCVPixelFormatType_420YpCbCr8BiPlanarFullRange = '420f',表示输出的视频格式为NV12;范围: (luma=[0,255] chroma=[1,255])
kCVPixelFormatType_32BGRA = 'BGRA', 输出的是BGRA的格式

https://www.jianshu.com/p/7da76246ce82

 
 
 kCVPixelFormatType_420YpCbCr8Planar = 'y420',
/* Planar Component Y'CbCr 8-bit 4:2:0. baseAddr points to a big-endian CVPlanarPixelBufferInfo_YCbCrPlanar struct */ kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange = '420v',
/* Bi-Planar Component Y'CbCr 8-bit 4:2:0, video-range (luma=[16,235] chroma=[16,240]). baseAddr points to a big-endian CVPlanarPixelBufferInfo_YCbCrBiPlanar struct */ kCVPixelFormatType_420YpCbCr8BiPlanarFullRange = '420f',
/* Bi-Planar Component Y'CbCr 8-bit 4:2:0, full-range (luma=[0,255] chroma=[1,255]). baseAddr points to a big-endian CVPlanarPixelBufferInfo_YCbCrBiPlanar struct */
#YpCbCr

Y分量:Y,U分量:Cb,V分量:Cr。即YUV格式的数据。

#8-bit

并且每个点采用8bit来保存一个Y的亮度。

#4:2:0

YUV的详细格式为:4:2:0。

# baseAddr points to a big-endian CVPlanarPixelBufferInfo_YCbCrPlanar struct

YUV数据的地址在CVPlanarPixelBufferInfo_YCbCrPlanar中以大端的形式存储。

#Planar & Bi-Planar

第一个是Planar模式,第二个是BiPlanar模式。
Planar格式就是单平面模式,在这个模式下,一个buf存储所有的数据。将Y、U、V分量分别打包,依次存储。即YYYY...U...V...即I420.
BiPlanar格式就是双平面模式,在这个模式下,亮度和色度被分成两个buf来存储。将Y和UV分别打包,一次存储。即YYYY...UV...即NV12.

#VideoRange & FullRange

亮度和色度的取值为8位,即2^8 = 256即可取值为【0-255】
VideoRange能取的值宽度为【16-235】
FullRange能取得值宽度为【0-255】

#采集信息查看

查看采集到的信息。

CMSampleBufferGetFormatDescription(sampleBuffer);
#如何从采集的CMSampleBufferRef中取得YUV数据

转化为CVImageBufferRef:

CVImageBufferRef buffer = CMSampleBufferGetImageBuffer(sampleBuffer);

获取宽高:

CVPixelBufferGetWidth(pixelBuffer);
CVPixelBufferGetHeight(pixelBuffer);

取得YUV数据地址:

CVPixelBufferGetBaseAddressOfPlane(pixelBuffer,Plane_index);
//这里的Plane_index与上文的Plane模式相关
如果是Plane模式则直接取到所有数据
如果是BiPlane则需要分两次,即Plane_index=0取得Y分量地址与Plane_index=1取得UV分量的地址
#注意事项

在操作pixelBuffer的时候记得加上锁

    CVPixelBufferLockBaseAddress(pixelBuffer, lockFlag);
//在这里操作
CVPixelBufferUnlockBaseAddress(pixelBuffer, lockFlag);

 

3.

/**
* 把 CMSampleBufferRef 转化成 UIImage 的方法,参考自:
* https://stackoverflow.com/questions/19310437/convert-cmsamplebufferref-to-uiimage-with-yuv-color-space
* note1 : SDK要求 colorSpace 为 CGColorSpaceCreateDeviceRGB
* note2 : SDK需要 ARGB 格式的图片
*/
- (UIImage *) imageFromSamplePlanerPixelBuffer:(CMSampleBufferRef)sampleBuffer{
@autoreleasepool {
CMFormatDescriptionRef desc = CMSampleBufferGetFormatDescription(sampleBuffer);
NSLog(@">>%@",desc); // 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, ); // Get the number of bytes per row for the plane pixel buffer
void *baseAddress = CVPixelBufferGetBaseAddressOfPlane(imageBuffer, ); // Get the number of bytes per row for the plane pixel buffer
size_t bytesPerRow = CVPixelBufferGetBytesPerRowOfPlane(imageBuffer,);
// Get the pixel buffer width and height
size_t width = CVPixelBufferGetWidth(imageBuffer);
size_t height = CVPixelBufferGetHeight(imageBuffer); uint8_t *rgbabuffer = baseAddress;
for (int y=; y<; y++) {
for (int x=; x<width;x++) {
rgbabuffer[y*bytesPerRow+x*+] = ;
rgbabuffer[y*bytesPerRow+x*+] = ;
rgbabuffer[y*bytesPerRow+x*+] = ;
rgbabuffer[y*bytesPerRow+x*+] = ;
}
} // 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, ,
bytesPerRow, colorSpace, kCGImageAlphaNoneSkipFirst | kCGBitmapByteOrder32Little);
// Create a Quartz image from the pixel data in the bitmap graphics context
CGImageRef quartzImage = CGBitmapContextCreateImage(context);
// Unlock the pixel buffer
CVPixelBufferUnlockBaseAddress(imageBuffer,); // 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);
}
}
 
 
04-30 10:59