GPUImageMovie Not Support Alpha Channel?

Question

I create Video Effect by GPUImage like this

self.overlayerView = [[GPUImageView alloc] init];
self.overlayerView.frame = self.view.frame;

dispatch_queue_t qu         


        

Answer 1

The GPUImage framework does not contain support for an alpha channel feature like that. There is a green screen feature, so if you pre-produce your video against a green screen then it is possible to split the video from the green screen background. But, what you describe here is an alpha channel video and a second video and that it not going to work properly because you are pulling from two different video sources at the same time and they will not stay in sync. Note that even with the green screen feature, there are issues with the exact edges, as described in this blog post (includes source code). The basic problem is that edges that are near green but not exactly green can be treated in odd ways by the filter ramp. Another approach you might want to think about is to just precompose the N frames down to 1 video before attempting to playback the video with the iOS video logic.