[PD] Interpolation

[Thomas Grill]

Hi Josh,
i generally can't recommend non-interpolating resampling except you're
always using very noisy sounds. The purer and lower-frequency your sounds
are the more you'll notice the resampling artefacts.
xsample uses the same algorithm as tabread4~ but _may_ be more efficient
since it uses SIMD instructions and explicit loop unrolling. xsample also
features linear (2-point) interpolation that should be a bit less
cpu-consuming.

best greetings,
Thomas

----- Original Message ----- 
From: "Josh Steiner" <josh at vitriolix.com>
To: "Frank Barknecht" <fbar at footils.org>
Cc: "PD List" <pd-list at iem.kug.ac.at>
Sent: Friday, March 12, 2004 10:15 PM
Subject: Re: [PD] Interpolation


> Frank Barknecht wrote:
>
> >Hallo,
> >Josh Steiner hat gesagt: // Josh Steiner wrote:
> >
> >
> >
> >>I have a question about interpolation, as in [tabread4~] vs. [tabread~]
> >>... my performance environment often has like 20-40 samplers playing
> >>simultaneously and its really beggining to bog down my cpu to the poitn
> >>where i'm getting dropouts, so i'm looking for ways of optimizing my
> >>patches.  i'm using tabread4~'s in it because i though this is more
> >>"correct" but i really dont know much about it.  how much does it really
> >>affect the sound if i am just using it as a simple sampler?  how much
> >>effeiciency gain can i expect from using non interpolated tabread?
> >>
> >>
> >
> >Why not just try it?
> >
> >
>
> i did and didnt notice any artifacts, but its hard to tell sometimes and
> i wouldnt want to rely on non interp. if later on i started to notice
> the artifacts :)
>
> actualy... the cpu usage with [tabread~] and [tabread4~] is identical in
> my little test here... hrm... i wonder if there are any more effiecient
> sample players... anyone have any suggestions?  i guess i'll go try out
> xsample/xgroove...
>
> >If you don't resample your samples, i.e. play everything at the
> >same, natural speed, you won't get any artivacts at all when using
> >tabread, as you don't need to interpolate at all.
> >
> >
>
>
> >But if you play your samples faster or slower, 4-point interpolation
> >has advantages.
> >
>
> ok, i do play back at variing speed so looks like i should stick with
> the interp. tabread.
>
> >I don't have any reference material at hand ATM, about
> >how much the introduced noise will be, but I know, that it's discussed
> >in the Dodge/Jerse "Computer Music" book. So if you can find that...
> >
> >ciao
> >
> >
>
> i read over MSP's chapter on interp. and all i got was a big wooshing
> sound as it shot over my head :)
>
>
> -- 
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