18 Jun
2010
18 Jun
'10
7:10 p.m.
On Thu, 17 Jun 2010 00:29:44 -0400
Jeremy <jeremybubs(a)gmail.com> wrote:
Hi,
When I'm programming, I find it immensely helpful to be able to plot audio
data at different points in its processing, for debugging, and to test new
ideas.
Essentially I want an oscilloscope, which plots each chunk of 1024 samples.
I've tried using libplot, but it seems too slow. It's causing constant
xruns, even when I only plot every 5th sample.
I thought that maybe libplot was too abstract, and that I needed to draw the
pixels on the screen directly. I tried using SDL, but it caused excessive
xruns also. Simply setting 48000 pixels per second was enough to cause the
flow of xruns. This is *not* erasing the screen, just drawing the points.
I'd expect that erasing the screen is the slow part, but apparently not.
How did you write your SDL program? Don't use any Setpixel functions.
Draw your pixels to a memory buffer/surface with the same pixel format
as the screen and flip that to the screen. Or try OpenGL. Use GL Arrays
if glBegin()/glEnd() is too slow.
The hardware shouldn't be a bottleneck if you don't use a system
older than 10 years or so. If you use OpenGL, you need an accelerated
driver of course, else it's useless.