[FFmpeg-devel] a64 encoder 7th round
Thu Feb 5 02:33:43 CET 2009
El Wed, Feb 04, 2009 at 08:02:02AM +0100, Bitbreaker/METALVOTZE escribio:
> > is this a fully unrolled loop?
> > because if it is i would expect the following to be faster
> No, not fully, but partly to save enough overhead, else memory usage
> would explode (though using this method i'd also save a few bytes in
> addition) :-) However as i write in $100 blocks i just need to increment
> one counter per round, so overhead is not too big. However smaller
> chunks are not possible that way, else i spoil linear writing even more
> and am forced to do the whole copy off the display. This way i can at
> least use time when the lower and upper part are displayed, what i need
> to. When i write completely linear i have more loop overhead unless i do
> a complete unroll of course, as you suggested, but then, the memory
> footprint is again kind of excessive. This will be around 5kb just
> unrolled loop.
But it's easy to generate the code at runtime. When the video ends, you
just reload the rest of the code. You have 64kb, 5kb is not that much for
temporary fast code.
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