> control-intensive, and memory-intensive The ideal "accelerator" for these kinds of jobs is a CPU with a big cache. Video encoding has well defined control l

> control-intensive, and memory-intensive The ideal "accelerator" for these kinds of jobs is a CPU with a big cache. Video encoding has well defined control loops and data paths that don't arbitrarily interfere with each other, so it's a good candidate for custom hardware. That is, you have a high bandwidth, highly parallel fast-path between framebuffer memory and functional units that compute FFTs and do motion vector operations, and a control plane that looks at a small handful variables in order to decide which data plane operations to schedule and how to glue together the final result. To run JS, you need a pile of functional units and lots of memory, and data for every operation needs to be able to come from / go to anywhere in memory. That's... just a general purpose computer.