七牛直播sdk 加滤镜

在这里面要做什么操作呢，各位有没有做过滤镜的，帮忙指导一下，感激不尽

---

self.context = [CIContext contextWithEAGLContext:[[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2]];

- (CVPixelBufferRef)cameraStreamingSession:(PLCameraStreamingSession *)session
             cameraSourceDidGetPixelBuffer:(CVPixelBufferRef)pixelBuffer
{
    CIImage *image = [CIImage imageWithCVImageBuffer:pixelBuffer];
    // 使用你自己的过滤器
    CIFilter *filter = [CIFilter filterWithName:@"CIHueAdjust" withInputParameters:@{kCIInputImageKey: image,
                                                                                     kCIInputAngleKey: @(15.0 / 180 * M_PI)}];
    CIImage *outImage = [filter valueForKey:kCIOutputImageKey];
    
    
    [self.context render:outImage
         toCVPixelBuffer:pixelBuffer];
    return pixelBuffer;
}