You're actually right about allocation - most video codecs are written with hardware decoders in mind which have fixed memory size. This is why their profiles h

You're actually right about allocation - most video codecs are written with hardware decoders in mind which have fixed memory size. This is why their profiles hard limit the memory constraints needed for decode - resolution, number of reference frames, etc. That's not quite the case for encoding - that's where things get murky since you have way more freedom at what you can do to compress better.