Jean-Baptiste Kempf

So your iframes.

So this works and operates in the spatial domain.

So you do your interprediction in the spatial domain, you have a residual because your prediction isn't quite matching that of reality.

So you've made a prediction, but then there's a little bit left, and that's what's known as the residual.

This is stored in the frequency domain, and these are quantized to decompand their space.

We then need to do the inverse transform to bring them back to the spatial domain and apply these residuals.

You should elaborate.

It's 30% better, but an order of magnitude, perhaps even two orders of magnitude more compression power.

That's the big difference.

Sorry, CPU power to achieve that level of compression.

And everything we've just said in the past couple of minutes,

every sentence is someone's lifetime's work.

There are books about every sentence.

So the level of complexity in many cases is inordinate.

Every sentence has thousands of people working on this in industry as a whole, books written about it.

So there's a lot of detail.

There's a lot of subtleties.

There's a lot of both academic and practical realities, both of which matter.

But broadly speaking, though, MP4 is understood to generally be H.264 plus AAC audio.

99% of the time, that's that and that.