[opus] CELT CFFT size configuration

[Diego Alejandro Parra Guzman]

Dear all.

According with my question.

CELT CFFT size configuration

I'm not completely sure about how the kiss_fft works for sizes which are
not power of two, as occur in the case of celt which calculate the mdct
using a fft sizes of 480, 240, 120, and 60, I guess that internally the
input data is padded with zeros in order to compute efficiently the mdct
using the Cooley and Tukey algorithm.

If I'm correct. Means that technically,  I could compute the fft using the
padding strategy and adjust the output such as kissfft done, someone could
confirm if that is possible.

thanks
cheers

On Wed, Apr 12, 2017 at 2:27 PM, Diego Alejandro Parra Guzman <
daparrag at correo.udistrital.edu.co> wrote:

> Dear all,
>
> Sorry for this simple and maybe stupid question, I'm working in the
> implementation of opus for ARMv7e microcontroller using a library CMSIS/DSP
> used to calculate the CFFT and MDCT based on the DCT-IV. my question is:
>
>
> In the implementation of Celt  you have used a fixed length CFFT equal to
> 1920, I want to know if there is some issues which can appear if a change
> that configuration for a cfft of size 2048, some of you could give me some
> support about that?, I ask because the library which I'm using doesn't
> support 1920 size.
>
> please let me know, I you need I could be more specific.
>
> thanks you so much.
>
> --
> Diego Alejandro Parra Guzmán
> Estudiante de ingeniería electrónica
> Universidad distrital FJC
>



-- 
Diego Alejandro Parra Guzmán
Estudiante de ingeniería electrónica
Universidad distrital FJC
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