keithmanlove

I know I shouldn't play with magic that I don't understand, but any

ideas on how to implement the cosine transform in Max?

I know I shouldn't play with magic that I don't understand, but any
ideas on how to implement the cosine transform in Max?

cosine-transform

Hello, many years passed... Did you find a solution?

what are you going to do? mpeg compression? ;)

Does the answer to that question help us find an answer?

here is a pretty good explanation on how to derive an algorithm to compute the DCT/FCT from an FFT.

https://dsp.stackexchange.com/questions/2807/fast-cosine-transform-via-fft

A [gen~] based approach in combination with the standard [fft~] object is one possible direction towards an implementation in Max.

For developers such as myself, another possibility would be to implement a custom Max external called [fct~] and [ifct]~ for example, leveraging solid and mature libraries such as FFTW for example.

However, the reason this thread caught my attention is that I have been fiddling with the idea of implementing a DCT and also a DST several times in the past, but I could never find any practical use for it related to music or audio in general. As Roman suggests with his comment, DCT is indeed mostly used in the realm of data compression, which is not part of the topics I spend my time investigating.

@LOADMESS in what context and for what purpose do you find useful computing a DCT?

Hi there,
here is a pretty good explanation on how to derive an algorithm to compute the DCT/FCT from an FFT.
https://dsp.stackexchange.com/questions/2807/fast-cosine-transform-via-fft 
It is not a very complex/difficult task.

A [gen~] based approach in combination with the standard [fft~] object is one possible direction towards an implementation in Max.

For developers such as myself, another possibility would be to implement a custom Max external called [fct~] and [ifct]~ for example, leveraging solid and mature libraries such as FFTW for example.
This wouldn't be a hard task either.

So I would be really curious to know:
@LOADMESS in what context and for what purpose do you find useful computing a DCT?

- Luigi

Cosine Transform