[Python-Dev] Test results of linuxaudiodev.c

[Michael Hudson]

Greg Ward <gward@mems-exchange.org> writes:

> Hi --
> 
> here are results from testing linuxaudiodev from the latest CVS Python
> 1.6.  This is on a Dell Dimension with on-board audio hardware: the
> Yamaha YMF724 chipset.  I'm using the ALSA 0.5.8a driver (the latest as
> of a week or two ago, and the only one that supports the YMF724).
> 
> Bottom line: the test sound plays, but it sounds horrible when played by 
> linuxaudiodev.  If I do this:
> 
>   $ play Lib/test/audiotest.au
> 
> then Cardinal Fang comes through loud and clear.  ("play" is a shell
> script wrapper for "sox", writing to /dev/dsp.)  But if I do this:
> 
>   $ ./python Lib/test/regrtest.py test_linuxaudiodev
> 
> he's still audible (and at the same volume), but very scratchy.  Sounds
> kind of like a very over-driven amp, or like a cheap car radio that
> somebody attacked with a knife.
> 
> [...some time passes...]
> 
> OK, I just tried it on another machine, also a Dell but with a different
> sound chip: the Crystal CS4232.  I'm pretty sure this one is using the
> OSS drivers included with the kernel, which is probably the second most
> important difference after the chipset itself.  Bottom line: it also
> sounds horrible.

Just tried that here; ouch.  I have a Dell Dimension XPS D233 (which
has an on-board Yamaha chipset - the OPL2, I believe).  I use the
sound driver that comes with the redhat built kernel (which is the OSS
one I think).

$ play audiotest.au

sounds fine,

$  ../../../build/python regrtest.py test_linuxaudiodev.py \
test_linuxaudiodev

sounds horrible; it sounds like it's being rammed through at far too
high a volume, but playing with the PCM or volume sliders in gmix has
no appreciable effect on the quality.  This suggests somewhat that the
problem lies in linuxaudiodev.c, doesn't it?

Is this stuff, like, documented anywhere?  I can't find any helpful
manpages...

I presume this module must work better than this for some people?

Cheers,
M.