Re: [Libvisual-devel] Re: Libvisual

[Dennis S. <sy...@yo...>]

On Wed, 2004-09-15 at 13:38 +0200, Burkhard Plaum wrote:
> > In the case that you get anough audio samples for
> > a high framerate, what is the use of asynchronous rendering? 
> 
> On weaker CPUs, one visualization plugin might slow down the whole
> process (in the worst case, also the audio playback). Imagine a player,
> which does something like:
> 
> while(1)
>    {
>    get_next_samples();
>    send_samples_to_soundcard();	
>    send_samples_to_libvisual();
>    }
> 
> If send_samples_to_libvisual() renders and displays everything
> synchronously, the soundcard buffer might underrun, which won't sound
> that good.
> So at least at one point between the playback loop (which drives the
> soundcard) and the visualization, things should be decoupled.
> 
> If it's in the application, inside libvisual, or inside the plugin,
> doesn't matter.

In this setup, you use a audio callback in the libvisual pipeline which
semi automaticly retrieves samples. Using that + have helper functions
to run the complete libvisual pipeline in a thread and this issue is
solved.

> > We're creating this, through improving libvisual and introducing
> > libvisual-display.
> 
> The libvisual-display seems to be crucial. Keep me updated, when
> there is something in CVS.

Cool, watch the list, bits will coming the upcoming weeks.

> Actually, lemuria does this for it's 256x256 texture: Copy the
> framebuffer into a texture and into memory, exchange some colors
> and copy it back into a second texture.
> Because sometimes the foreground and background have
> the same texture image, only the colors are swapped.

Well, ok but here it's a small texture and for special purpose.

> The funny thing is, that most people think, they are completely
> different images :-)

Hehehehe!

Cheers,
Dennis