iOS CVImageBufferRef

CVPixelBufferRef

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/*!
@typedef CVPixelBufferRef
@abstract Based on the image buffer type. The pixel buffer implements the memory storage for an image buffer.
*/
/**
CVPixelBuffer(core video pixel buffer): 指的是主内存中的图片缓存,用来保存图片像素数据。应用程序在产生图片帧、解压缩视频数据或调用Core Image的时候可以调用此对象
**/
CVPixelBufferRef pixelBuffer = (CVPixelBufferRef)pixel;
CVPixelBufferUnlockBaseAddress( pixelBuffer, 0 );
CVPixelBufferRelease( pixelBuffer );

1.CVPixelBufferRef to image

see +(UIImage *)imageFromCVPixelBufferRef:(CVPixelBufferRef)pixelBuffer method

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static OSStatus CreateCGImageFromCVPixelBuffer(CVPixelBufferRef pixelBuffer, CGImageRef *imageOut)
{
OSStatus err = noErr;
OSType sourcePixelFormat;
size_t width, height, sourceRowBytes;
void *sourceBaseAddr = NULL;
CGBitmapInfo bitmapInfo;
CGColorSpaceRef colorspace = NULL;
CGDataProviderRef provider = NULL;
CGImageRef image = NULL;
sourcePixelFormat = CVPixelBufferGetPixelFormatType( pixelBuffer );
if ( kCVPixelFormatType_32ARGB == sourcePixelFormat )
bitmapInfo = kCGBitmapByteOrder32Big | kCGImageAlphaNoneSkipFirst;
else if ( kCVPixelFormatType_32BGRA == sourcePixelFormat )
bitmapInfo = kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipFirst;
else
return -95014; // only uncompressed pixel formats
sourceRowBytes = CVPixelBufferGetBytesPerRow( pixelBuffer );
width = CVPixelBufferGetWidth( pixelBuffer );
height = CVPixelBufferGetHeight( pixelBuffer );
CVPixelBufferLockBaseAddress( pixelBuffer, 0 );
sourceBaseAddr = CVPixelBufferGetBaseAddress( pixelBuffer );
colorspace = CGColorSpaceCreateDeviceRGB();
CVPixelBufferRetain( pixelBuffer );
provider = CGDataProviderCreateWithData( (void *)pixelBuffer, sourceBaseAddr, sourceRowBytes * height, ReleaseCVPixelBuffer);
image = CGImageCreate(width, height, 8, 32, sourceRowBytes, colorspace, bitmapInfo, provider, NULL, true, kCGRenderingIntentDefault);
if ( err && image ) {
CGImageRelease( image );
image = NULL;
}
if ( provider ) CGDataProviderRelease( provider );
if ( colorspace ) CGColorSpaceRelease( colorspace );
*imageOut = image;
return err;
}
static void ReleaseCVPixelBuffer(void *pixel, const void *data, size_t size)
{
CVPixelBufferRef pixelBuffer = (CVPixelBufferRef)pixel;
CVPixelBufferUnlockBaseAddress( pixelBuffer, 0 );
CVPixelBufferRelease( pixelBuffer );
}
+(UIImage *)imageFromCVPixelBufferRef:(CVPixelBufferRef)pixelBuffer{
UIImage *image;
@autoreleasepool {
CGImageRef cgImage = NULL;
CVPixelBufferRef pb = (CVPixelBufferRef)pixelBuffer;
CVPixelBufferLockBaseAddress(pb, kCVPixelBufferLock_ReadOnly);
OSStatus res = CreateCGImageFromCVPixelBuffer(pb,&cgImage);
if (res == noErr){
image= [UIImage imageWithCGImage:cgImage scale:1.0 orientation:UIImageOrientationUp];
}
CVPixelBufferUnlockBaseAddress(pb, kCVPixelBufferLock_ReadOnly);
CGImageRelease(cgImage);
}
return image;
}
//第二种
+(UIImage *)imageFromCVPixelBufferRef2:(CVPixelBufferRef)pixelBuffer{
CVPixelBufferRef pb = (CVPixelBufferRef)pixelBuffer;
CVPixelBufferLockBaseAddress(pb, kCVPixelBufferLock_ReadOnly);
int w = CVPixelBufferGetWidth(pb);
int h = CVPixelBufferGetHeight(pb);
int r = CVPixelBufferGetBytesPerRow(pb);
int bytesPerPixel = r/w;
unsigned char *buffer = CVPixelBufferGetBaseAddress(pb);
UIGraphicsBeginImageContext(CGSizeMake(w, h));
CGContextRef c = UIGraphicsGetCurrentContext();
unsigned char* data = CGBitmapContextGetData(c);
if (data != NULL) {
int maxY = h;
for(int y = 0; y<maxY; y++) {
for(int x = 0; x<w; x++) {
int offset = bytesPerPixel*((w*y)+x);
data[offset] = buffer[offset]; // R
data[offset+1] = buffer[offset+1]; // G
data[offset+2] = buffer[offset+2]; // B
data[offset+3] = buffer[offset+3]; // A
}
}
}
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
CVPixelBufferUnlockBaseAddress(pb, kCVPixelBufferLock_ReadOnly);
return img;
}

2.CMSampleBufferRef to image

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+ (UIImage *) imageFromSampleBuffer:(CMSampleBufferRef) sampleBuffer
{
// 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);
}

3.image to CVPixelBufferRef,这个方法CGContextDrawImage 占用很高的CPU

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+ (CVPixelBufferRef) pixelBufferFromCGImage: (CGImageRef) image
{
CGSize frameSize = CGSizeMake(CGImageGetWidth(image), CGImageGetHeight(image));
NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithBool:NO], kCVPixelBufferCGImageCompatibilityKey,
[NSNumber numberWithBool:NO], kCVPixelBufferCGBitmapContextCompatibilityKey,
nil];
CVPixelBufferRef pxbuffer = NULL;
CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault, frameSize.width,
frameSize.height, kCVPixelFormatType_32BGRA, (CFDictionaryRef) options,
&pxbuffer);
NSParameterAssert(status == kCVReturnSuccess && pxbuffer != NULL);
CVPixelBufferLockBaseAddress(pxbuffer, 0);
void *pxdata = CVPixelBufferGetBaseAddress(pxbuffer);
CGColorSpaceRef rgbColorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(pxdata, frameSize.width,
frameSize.height, 8, 4*frameSize.width, rgbColorSpace,
kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipFirst);
CGContextDrawImage(context, CGRectMake(0, 0, CGImageGetWidth(image),
CGImageGetHeight(image)), image);//这个站CPU 相当高
CGColorSpaceRelease(rgbColorSpace);
CGContextRelease(context);
CVPixelBufferUnlockBaseAddress(pxbuffer, 0);
return pxbuffer;
}