Quite remarkable! (Lua as a waveform visualisator)

[Asko Kauppi <asko.kauppi@...>]

I eventually did it only the "userdata int array" way, as suggested on  
the list, and the results are quite remarkable:

Lua:
[iMac:~/TestBox/Sources/luax-perforce] asko% ./luax  
Apps/sdl_mixer/sdlwav.lua
	out_darwin/luax_gui -w -l kernel -v Apps/sdl_mixer/sdlwav.lua

	Lua 5.1 (work4)  Copyright (C) 1994-2004 Tecgraf, PUC-Rio
	USES 'lib.sdl2' (global):  
/Users/asko/TestBox/Sources/luax-perforce/Modules/SDL2/sdl2_wrap.lua
	USES 'lib.sdl_mixer' (global):  
/Users/asko/TestBox/Sources/luax-perforce/Modules/SDL_mixer/ 
sdl_mixer_wrap.lua
	Opened audio at 44100 Hz 16 bit stereo, 512 samples buffered
	fps=13.70

Native C:
[iMac:~/TestBox/Sources/luax-perforce] asko% Apps/sdl_mixer/sdlwav  
Apps/sdl_mixer/funky.mp3
	Opened audio at 44100 Hz 16 bit stereo, 512 bytes audio buffer
	fps=43.22


The application is an SDL mixer demo that plays a tune and  
simultaneously shows its waveform on the screen.  The 43->13 fps change  
is hardly noticable to the eye, certainly much less than I expected  
(the C code is tight, and the mixed sound data is passed as 2048 bytes  
per callback).  Well done, Lua!!  :)

-ak


 a) table:
> > 	+ conceptually "the right thing"
> > 	- performance must be lowest?
>
> Have you tested it? If performance is low, you can try to reuse a table
> (instead of creating a new one for each call).
>
>
> > b) ... (lots of integer values):
> > 	+ fast to send, fast to receive
> > 	- is there a limit to the number of args one can get?  is 10000 too
> > many?
>
> Far too many.
>
> -- Roberto