I've written a NEON based rgb2yuv routine (unscaled): https://github.com/dreifachstein/ThirdParty-FFmpeg/blob/rgb2yuv-neon/libswscale/arm/rgb2yuv_neon.S It is rgbatonv12 only for now and has not be integrated with libswscale. I am willing to improve it for possible inclusion into ffmpeg. Any feedback is welcome.