Twitch no longer recommend Main profile on their "Broadcast requirements"
page. The number of devices that can't decode High profile is very small
and limited to old, legacy devices such as the 1st generation iPad (six
years old). Additionally, these devices have limited resolution / FPS
support, so streams are often encoded at levels beyond what they could
decode even disregarding the H264 profile requirement. It's not worth
degrading the quality of streams for modern devices just to support these
legacy decoders. Twitch still provides low-complexity transcodes for
devices which cannot handle Source quality streams.
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