If its just one channel thats pretty easy, using the intel GPU (VA-API) you can transcode 4mbps to 2mbps with minimal cpu usage. transcoding 70x 4mbps feeds into 70x 2mbps feeds is going to be tough.
Different processor would mean different precompiled binaries. They'd need to release open source drivers. Till then the open source drivers that others are writing are as good as your getting. We're working hard to improve support the best we can.