We haven't tried a paid service, although my sense is that YouTube does represent the best-of-breed in commercially available parallel transcoding (free as it i

We haven't tried a paid service, although my sense is that YouTube does represent the best-of-breed in commercially available parallel transcoding (free as it is to users). I'd encourage you to try it with a paid service and see where the time-to-finished 4K output shakes out. I'd be surprised if it's better but eager to learn either way. ExCamera is doing it at 6x-30x real time (which is important if you want to make a cloud video editor); I don't think you can buy that commercially today. Ultimately, YouTube uses chunks of 128 frames each because it's too expensive to put key frames much more frequently than that, and other transcoding services will face a similar limitation. ExCamera's purely functional encoder lets it use chunks smaller than the interval between key frames, so the effective degree of parallelism can be a lot higher. (Obviously there's a lot of overhead from using a software codec -- we think hardware codecs should support a "save/restore state" interface too. I think we do have to prototype first in software to demonstrate the benefits before hardware people will take us seriously.)