[FFmpeg-devel] [PATCH 1/2] lavu/tx: add real to real and real to imaginary RDFT transforms

[Lynne]

Aug 3, 2023, 18:26 by dev at lynne.ee:

> These are in-place transforms, required for DCT-I and DST-I.
>
> Templated as the mod2 variant requires minor modifications, and is
> required specifically for DCT-I/DST-I.
>
> Quite optimized, as there's no need for any additional buffer storage.
>

Specifically, for R2R, vs fftw
  26280 decicycles in           av_tx (r2c), 1048574 runs,      2 skips
  69940 decicycles in         fftwf_execute, 1048576 runs,      0 skips

And for R2I
  25856 decicycles in           av_tx (r2c), 1048571 runs,      5 skips
  65561 decicycles in         fftwf_execute, 1048576 runs,      0 skips