[linux-audio-dev] Re: latencytest problem with 2.5.44-mm2

[Joern Nettingsmeier]

Benno Senoner wrote:
> 
> Hello Joern,
> Are you using ALSA right ?

i think so :)

> Perhaps an OSS emulation problem of ALSA ?

unlikely. if i use "play" on the very same file i use for latencytest,
it plays ok.
afaik, play is oss, so my oss emulation seems ok.
aplay also works.


> I recall that I got grabled sound (even lockups) on the SBLive
> when using 128byte fragments (seemed like a driver or hardware problem).
> What kind of audio card do you have ?

sblive. fun thing is, it used to work with kernels before 2.5.44....
ok, maybe the kernel just performs horribly, *BUT*:
i run do_tests, the sound is horrible, but when i aplay the same
soundfile *during the test*, i can hear clear audio over the garbage
(sblive does hardware mixing).

> Anyway latencytest is completely outdated (does not compile cleanly
>  on newer distros due to wrong includes etc).
> Now that I have some spare time again (seems unbelievable but I were
>  able to finish my university degree in CS just a month before turning
> 30 ... better late than newer as we use to say :-) )
> I'll try to rewrite some of the useful tools including latencytest,
> adding alsa support and new stress test methods and like one guy of the
> list asked , the possibility to chose the disks (or the path) on which
> perform the disk i/o tests.

as i said, what irritates me is it used to work a few days ago...
 
> Anyway low latency came useful in my thesis since a part of the project
> consisted in a real time laser scanner that tracks a laser spot that
>  you move over the object you like to scan that is filmed by two cameras
>  that permit a 3D reconstruction of the surface.
> (at 25 FPS we have processing cycles of 40msec so it is quite easy for
> the low lat patch to keep up since there is basically no disk i/o
> present during the scanning activity).

it would be most welcome to have a reworked latencytest program. now
that 2.5. is almost into feature-freeze, we need to jump in, run tests
and bug the kernel guys for latency optimization. i fear most of the
tweaking has been to maximize throughput, which does not buy us much for
audio...

best,

jörn




-- 
Jörn Nettingsmeier     
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