YCbCr (NV12) texture scaling using r5p1 drivers on Mali400

Hi,

I have a use-case where NV12 video frames are imported as GL texture (using EXT_image_dma_buf_import, dma_buf) and would like to down-scale the said texture into also a destination NV12 buffer (render target). The destination NV12 buffer will hold 2x2 scaled-down video frames (a mosaic).

Is this doable on Mali400? If so, is it possible to explain the necessary setup + fragment shader to use?

(E.g. the quite new EXT_YUV_target extension for gles3.0 would help achieve that?)

Best regards,

Ilyes Gouta