[vorbis-dev] Look what I found under the Xmas tree!

Michael Smith msmith at labyrinth.net.au
Sun Dec 24 20:16:33 PST 2000

At 08:23 AM 12/24/00 +0100, you wrote:
>Hello people,
>Looks like Santa Claus thinks I've been a good boy this year.
>Here's the third in my performance patch series: d.m.l
>Apply after applying d.o.n and d.n.m; I don't know how much of
>those got applied to the CVS tree.


In future, it'd be much better if you split patches up into seperate parts - optimisations, and other changes. Optimisations can (usually) be applied as-is. Your other changes probably won't be, since they make pretty major functional changes sometimes.

Also, could you please _explain_ functional changes? I haven't looked at this one properly yet, but the previous one made huge changes to the psychoacoustics and short block triggering with ZERO explanation. As a result, it's been ignored (your other patch was applied completely, I think, since it didn't make functional changes, just speed ones).

>What's inside:
>Request for help! Look in os.h if you're using a compiler or
>processor I don't use (I use gcc on K5, K7, G3).

What sort of performance increases do you see from this (when you actually use it)? Why 32-byte alignment - the reasons for having aligned allocations is obvious, but is 32 bytes actually beneficial (does this give you cache line alignment or something?)

>New MDCT! Now we have two; competition is a good thing. Let's
>see which one is fastest :-)

How much faster is your new one for the case it handles?

>Changed the ATH_Bark_dB array. This removes some very annoying
>artifacts when encoding low-frequency, tonal sounds.

This seems like a dubious change. I suspect it's just hiding an actual problem elsewhere. This is what I mean - explain WHY you've done things like this, in reasonable detail, rather than just saying "I think it makes it better sometimes".


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