[linux-audio-user] [ANN] jack_oscrolloscope 0.1

Reuben Martin reuben.m at gmail.com
Tue Nov 21 20:37:19 EST 2006


On 11/21/06, Dominic Sacré <dominic.sacre at gmx.de> wrote:
> On Tuesday 21 November 2006 21:42, Fons Adriaensen wrote:
> > > I assume you're using SDL. If you can, try OpenGL, that should take
> > > most of the work off the CPU.
> >
> > Rather the opposite, see below.
> >
> > > Another thing you could try is to change both occurences of
> > > SDL_HWSURFACE in video.h to SDL_SWSURFACE. Does it make any
> > > difference? On my machine it doesn't, so I wasn't sure what to use.
> >
> > It does help a bit, but not with -g:
> >        |           -g
> >     ---------------------
> >     HW |   33%     94%
> >     SW |   22%     93%
>
> Well, this flag is not used in GL mode, so it's no surprise that it has no
> effect there. But it looks like I should be using software surfaces in
> SDL mode.
>
> Do you have hardware accelerated OpenGL at all? Software emulated GL can
> be dog slow (much slower than SDL), that's the main reason why I added
> SDL support in the first place.
> For comparison, on my machine, with 12 tracks, fullscreen 1280x960, I'm
> getting about 30% CPU load using OpenGL. That's with an Athlon XP 3000+
> and a cheap, 4 year old, passively cooled Nvidia card.

I've a similar Athlon/nvidia setup. If I use OpenGL as root with -f 0
then all is well. If I use the -f 0 as a normal user my CPU goes to
100%. Just using -g by itself doesn't cause the CPU to race, but it
can easily lock things up. (The keyboard locks up, the display
freezes, but the mouse still works) SDL mode is more stable and
doesn't seem to use the CPU any more than the OpenGL mode.

>
> > I've got an almost identical app
> > (Yass - not yet released). With 100 updates per second, 32 channels,
> > and the maximum scrolling speed it takes less than 1% of available CPU.
> > So it's definitely not X11 taking all the time.
>
> Wow, 1%?! Is that using plain X11? Sounds almost too good to be true.
> I think it goes without saying that I'd be interested in seeing your
> code ;)
>
>     Dominic
>


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