[SDL] Creating audio samples via code

[Simon]

Stretching the sound wave will change its pitch, and will sound differently.
You might want to make the sound longer in time, but probably the
same, then you'll need high-tech algorythms to reconstruct the right
pitch.

This type of algorythm is used to strech the audio part of a movie to
help synchronise the movie with the sound without loosing any frames.
(And in fact i heard there was a patent on it, for movie playback that
is!).

If you wish to learn about this type of calculation, give a visit to
http://csounds.com/ a nice place to learn about audio theories.

Good luck,
  Simon

On 5/21/07, Gabriel Gambetta <mystml at adinet.com.uy> wrote:
> Hi guys,
>
> We're making a game where we need to time-stretch some audio samples. My
> idea is to load the samples normally and then create the stretched
> samples on the fly.
>
> The thing is, I can't find anything in SDL_mixer.h to create and
> manipulate samples, except for the Mix_Chunk itself.
>
> So two questions. First, if I just allocate a Mix_Chunk and its abuf
> field and put stuff there, assuming the stuff is in the correct format,
> should it work?
>
> Second, would you be interested in a patch to add some functions to do
> that? Say, Mix_CreateChunk(), Mix_GetSample() and Mix_PutSample()?
>
> BTW, if someone has SDL_Mixer code to do time-stretching, you'll save me
> a lot of work ;)
>
> Thanks,
>
>         --Gabriel
>
> ________________________________________________________________________
> Gabriel Gambetta
> Mystery Studio - http://www.mysterystudio.com
> Gabriel's Stuff - http://www.mysterystudio.com/gabriel
>
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