Your step 2 is way too slow to support real-time rendering… and it looks like you’re missing a couple of steps. For your purpose, you would typically:
Setup:
- create a pool of
CVPixelBuffer
– usingCVPixelBufferPoolCreate
- create a pool of metal textures using
CVMetalTextureCacheCreate
For each frame:
- convert
CMSampleBuffer
>CVPixelBuffer
>CIImage
- Pass that
CIImage
through your filter pipeline - render the output image into a
CVPixelBuffer
from the pool created in step 1 - use
CVMetalTextureCacheCreateTextureFromImage
to create a metal texture with your filtered CVPixelBuffer
If setup correctly, all these steps will make sure your image data stays on the GPU, as opposed to travelling from GPU to CPU and back to GPU for display.
The good news is all this is demoed in the AVCamPhotoFilter sample code from Apple https://developer.apple.com/library/archive/samplecode/AVCamPhotoFilter/Introduction/Intro.html#//apple_ref/doc/uid/TP40017556. In particular see the RosyCIRenderer
class and its superclass FilterRenderer
.