Subject: Re: [linux-audio-dev] gain curves, interpolation, etc.
From: Paul Sladen (paul_AT_sladen.org)
Date: Wed Nov 29 2000 - 11:42:41 EET
On 28 Nov 2000, Jack O'Quin wrote:
> [bla...bla about effecitent interpolation methods
>
> Does anyone know what to do about it?
Yes!
1. Compute the actual value from the polynomial every 8/16/32 samples.
2. Linearily interpolate between.
-*-
#define GRANULARITY ( 32 )
#define GRANULARITY_OVER_1 ( 1/32 )
for(;;)
{
x = 2*t^3 + 3*t^2 - t + 10;
dx = (x - lastx) * GRANULARITY_OVER_1;
for( i=0; i < GRANULARITY; i++)
*out++ = *in++ * (x += dx);
t += GRANULARITY;
lastx = x;
}
-*-
Not fine enough? -- Lower the granularity;
Not fast enough? -- Raise the granularity;
HTH,
Paul
-- e: paul_AT_sladen.org t: 0115 922 7162
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