And speed versus quality can each be a fixed variable in comparisons. So one interesting question is "how does speed compare when x264 is run at settings that produce equivalent quality?"
HW can get interesting when it can be faster than even the lowest quality software settings. It can also be interesting where it doesn't use resources that can be spent on other bottlenecks, like source decode or preprocessing.
Also, fewer joules-per-minute or lower TCO-per-minute can matter for high volume facilities.
I'm joining the Amazon.com video tram as a encoding quality and workflow guru starting Monday, so these questions have rather been on my mind
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