[vorbis] RC3: I'm impressed

[John Morton]

On Tuesday 15 January 2002 23:43, Nathan I. Sharfi wrote:
> On 15 Jan 2002, Hongl Lai wrote:
> > On Tue, 2002-01-15 at 00:33, Craig Dickson wrote:
> > > Joel wrote:
> > > > What about translating some critical functions to hand optimized
> > > > assembly.
> > >
> > > Goodbye, portability. Hello, 5% speed increase. Probably not a good
> > > idea.
> >
> > #ifdef x86
> >   insert asm code here
> > #endif /* x86 */
> >
> > Hello, portability. Welcome, speed increase.
>
> Considering the rate at which processors get faster and cheaper, do you
> really think this is worth the hassle and time?

There is presently a noticable speed difference between the vorbis decoder 
and the mp3 decoder in xmms on sub Duron/Celeron system, which I expect 
people will use for things like dedicated jukeboxes at home, in the office 
and in DIY car stereo systems. It really starts to matter if the same machine 
is doing other CPU intensive tasks, like decoding several streams at once, 
applying sound filters, displaying a video stream at the same time. A spot of 
hand optimized assembly made a big difference to a lot of mp3 decoders, so 
there's no reason to think it won't improve the vorbis decoder.

Of course, the point where you start to think about doing it is when you've 
gotten as much as you can out of hand optimizing the C code and choosing the 
right complier flags.

John

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