从 CIImage 创建 CVPixelBufferRef 以写入文件

Question

我正在编写一个自定义电影录制应用程序，并实现了 AVAssetWriter 和 AVAssetWriterInputPixelBufferAdaptor 用于将帧写入文件。在 DataOutputDelegate 回调中，我尝试将 CIFilter 应用于 sampleBuffer。首先我得到一个 CVPixelBufferRef 然后创建一个 CIImage。然后我应用 CIIFilter 并获取生成的 CIImage：

    CVPixelBufferRef pixelBuffer = (CVPixelBufferRef)CMSampleBufferGetImageBuffer(sampleBuffer);

    CIImage *image = [CIImage imageWithCVPixelBuffer:pixelBuffer];
    CIFilter *hueAdjust = [CIFilter filterWithName:@"CIHueAdjust"];
    [hueAdjust setDefaults];
    [hueAdjust setValue: image forKey: @"inputImage"];
    [hueAdjust setValue: [NSNumber numberWithFloat: 2.094]
                 forKey: @"inputAngle"];

    CIImage *result = [hueAdjust valueForKey: @"outputImage"];

    CVPixelBufferRef newBuffer = //Convert CIImage...

我将如何转换 CIImage 以便我可以：

    [self.filteredImageWriter appendPixelBuffer:newBuffer withPresentationTime:lastSampleTime];

Answer 1

更新答案

虽然我以前的方法有效，但我能够对其进行调整以简化代码。它似乎也运行得更快。

samplePixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
CVPixelBufferLockBaseAddress(samplePixelBuffer, 0); // NOT SURE IF NEEDED // NO PERFORMANCE IMPROVEMENTS IF REMOVED

NSDictionary *options = [NSDictionary dictionaryWithObject:(__bridge id)rgbColorSpace forKey:kCIImageColorSpace];                
outputImage = [CIImage imageWithCVPixelBuffer:samplePixelBuffer options:options];

//-----------------
// FILTER OUTPUT IMAGE

@autoreleasepool {

    outputImage = [self applyEffectToCIImage:outputImage dict:dict];

}
CVPixelBufferUnlockBaseAddress(samplePixelBuffer, 0); // NOT SURE IF NEEDED // NO PERFORMANCE IMPROVEMENTS IF REMOVED

//-----------------
// RENDER OUTPUT IMAGE BACK TO PIXEL BUFFER

[self.filterContext render:outputImage toCVPixelBuffer:samplePixelBuffer bounds:[outputImage extent] colorSpace:CGColorSpaceCreateDeviceRGB()]; // DOES NOT SEEM TO WORK USING rgbColorSpace

以前的答案

我刚刚实现了以下从 CIImage 获取像素缓冲区。确保您的像素格式一致，否则您将遇到颜色问题。 CFDictionaries 也非常重要。 http://allmybrain.com/2011/12/08/rendering-to-a-texture-with-ios-5-texture-cache-api/

CFDictionaryRef empty = CFDictionaryCreate(kCFAllocatorDefault, // EMPTY IOSURFACE DICT
                                           NULL,
                                           NULL,
                                           0,
                                           &kCFTypeDictionaryKeyCallBacks,
                                           &kCFTypeDictionaryValueCallBacks);
CFMutableDictionaryRef attributes = CFDictionaryCreateMutable(kCFAllocatorDefault,
                                                         1,
                                                         &kCFTypeDictionaryKeyCallBacks,
                                                         &kCFTypeDictionaryValueCallBacks);

CFDictionarySetValue(attributes,kCVPixelBufferIOSurfacePropertiesKey,empty);

CVPixelBufferRef pixelBuffer = NULL;
CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault, 
                                      outputImage.extent.size.width, 
                                      outputImage.extent.size.height, 
                                      kCVPixelFormatType_32BGRA, 
                                      attributes, 
                                      &pixelBuffer);

if (status == kCVReturnSuccess && pixelBuffer != NULL) {

    CVPixelBufferLockBaseAddress(pixelBuffer, 0); // NOT SURE IF NEEDED // KEPT JUST IN CASE
    [self.filterContext render:outputImage toCVPixelBuffer:pixelBuffer bounds:[outputImage extent] colorSpace:CGColorSpaceCreateDeviceRGB()];
    CVPixelBufferUnlockBaseAddress(pixelBuffer, 0); // NOT SURE IF NEEDED // KEPT JUST IN CASE

}