IDCT

Hi!

I just implemented an IFFT on a DSP and now I=B4d like to know, what has =

to be done, so that I can use that IFFT as an IDCT.

Thanks,
Matthias

Matthias Alles wrote:
> I just implemented an IFFT on a DSP and now I�d like to know, what has 
> to be done, so that I can use that IFFT as an IDCT.

See the FFTPACK source code (or FFTW) for an example of how you can 
compute an IDCT (a.k.a. a type-III DCT) via pre/post-processing of a 
real-input FFT.  (If you have a complex FFT algorithm, of course there 
are standard tricks to use it for a real-data transform of twice the 
length.)

Steven G. Johnson wrote:

> See the FFTPACK source code (or FFTW) for an example of how you can 
> compute an IDCT (a.k.a. a type-III DCT) via pre/post-processing of a 
> real-input FFT.  (If you have a complex FFT algorithm, of course there 
> are standard tricks to use it for a real-data transform of twice the 
> length.)

Thanks for the tip!