Re: [Traverso-devel] line based audio painting in cvs

[Nicola Döbelin]

Am Montag, 7. Januar 2008 21.27:37 schrieb Nicola Döbelin:
> Am Montag, 7. Januar 2008 20.57:26 schrieb Remon:
> > > Every action requiring a redraw of the audio clip (dragging, gain, or
> > > just soft-selection) lags about 1 sec behind the cursor. According to
> > > top it's a problem with X, as I can easily saturate the CPU with X by
> > > moving the cursor on the screen and causing a lot of soft selections.
> > > It doesn't matter how long the displayed region is. The clips I was
> > > using were only 3 minutes long, but their source files were > 1 hour.
> >
> > Sounds like a serious problem too me though :P
>
> Yeah moving clips with 1 fps is no fun. You never know if it snapped or
> not. And zooming takes > 3 seconds per step. But now that I can import
> audio files again ;-) I found out that what I wrote before is not quite
> correct. It depends on how much of the clip is visible on the screen, the
> file size is irrelevant. So it boils down to horribly poor painting
> performance, but no relation to file size or absolute clip length. My
> screen is 1680 px wide, so if there are painting problems, I will
> definitely notice it. The PC also has an Nvidia GPU (5600 something).
> Someone from KDE noticed that the CSS drivers have massive performance
> problems wit Qt4 (see
> http://nowwhatthe.blogspot.com/), maybe this adds to the problem. I'm
> copying the >1h files to my notebook right now, which has an onboard intel
> GPU. These didn't show any problems with Qt4 in the profiling tests of the
> KDE blogger. I'll let you know how it works in a few minutes.

Ok, it seems to be the Nvidia/Qt4 combination. The behaviour with two tracks, 
each containing a 1 h 50 min mono recording, on different systems is as 
follows:

Macbook with 2 x 2 GHz, Intel 945 GPU, window size 1280x800: All actions super 
smooth!

Intel 2 x 2.6 GHz CPU, NVidia 5600 GPU, window size 1280x800: Jerky, but 
usable. Update rate when dragging clips probably 2-4 fps.

Intel 2 x 2.6 GHz CPU, Nvidia 5600 GPU, window size 1680x1050: Unusable. 
Update rate when dragging clips around 1 fps, when zooming < 1 fps.

(The macbook runs Kubuntu Gutsy with Qt 4.3.2, the other one Mandriva 2007.10 
with Qt 4.3.1. Both use KWin as window manager, not Compiz.)

So it's not your fault ;-) Hopefully the release of KDE4 is important enough 
for Xorg / NVidia / Trolltech to sort these problems out soon.

As for the different wave form painting, I can't detect any difference in CPU 
load on the macbook. It's always around 3% for traverso and 1% for xorg while 
playing, regardless of the zoom level and painting method.

Greetings
Nic