27 Jul
2009
27 Jul
'09
7:45 a.m.
On Sun, Jul 26, 2009 at 09:15:20PM -0500, Gabriel M. Beddingfield wrote:
On Sat, 25 Jul 2009, Justin Smith wrote:
FFTW3 can handle almost any size you want. If the size has
a large prime factor the transform may be significantly
slower, but for something like 5120 = 5 * 2^10 the speed
loss will be quite moderate.
>
> I am using the fftw3 library to implement a transform in a array of 5120
> elements .
> I have this array from a program that I created modifying the arecord
> program.
[snip]
I don't know fftw specifically, but I am fairly certain that you need
a table size that is an even power of two for fft in general (maybe
you can adjust your code to use 4096 or 8192?).
Ditto that.
If your data is 5120 samples... either truncate it to 4096 samples or pad
it with zeros util you have 8192 samples. (The zeros won't affect your transform.)
They do affect it but in many cases not in a way that
matters to your application. Depends on the app.
Ciao,
--
FA
Io lo dico sempre: l'Italia รจ troppo stretta e lunga.