[SDL] Google SoC proposal: Real Time Pitch Shifter

[Thiago Bolaum]

Hi Ryan!
I finished my application today. Can I send it to you? May you could tell me
what can I do to improve it. I dont really know if I covered all topics that
you want to know about.

Thanks very much

On Fri, Mar 21, 2008 at 4:31 PM, Ryan C. Gordon <icculus at icculus.org> wrote:

>
> >  Well, if you have any tips on how I could write a nice proposal it
> would
> > be very nice!
>
> I don't know the formal process for applying, but here's the gist of
> that project:
>
> SDL_mixer has what we call an "effects" API...basically there is a
> callback that can modify a playing sound before it's mixed into the
> output buffer, or modify the output buffer itself right before it goes
> to the hardware.
>
> Applications can supply this callback, but there are a few built-in
> callbacks that can be exploited by the application, too.
>
> The built-in effects that are there are relatively simple: simple 2D
> panning and attenuation (and "positional" audio which is just basic
> panning and attenuation combined), and left/right reversal of stereo data.
>
> Please read the comments in SDL_mixer.h, where it says "Special Effects
> API" ...
>
>
>
> http://www.libsdl.org/cgi/viewvc.cgi/trunk/SDL_mixer/SDL_mixer.h?revision=3571&content-type=text%2Fplain
>
>
> Mix_SetPanning(), Mix_SetDistance(), and Mix_SetReverseStereo() are
> examples of built-in effects. We'd be looking for a new one, like
> Mix_SetPitch().
>
> Part of the dilemma is that we would need the pitch shifting effect to
> not change the size of the data, so you can't just do a resample. You're
> probably going to have to bust out some FFTs.
>
> --ryan.
>
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>



-- 
Thiago 'bolaum' Borges Abdnur
----------------------------------
"Trust no one..."
- Deep Throat (The X-Files)
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