Re: Audio skipping with alsa

[Jaroslav Kysela]

On Wed, 10 Sep 2003, Takashi Iwai wrote:

> At Tue, 09 Sep 2003 15:14:21 +0100,
> Russ Garrett wrote:
> >
> > Hi, I've just installed an M-Audio Audiophile 2496 sound card (Envy24)
> > with the 2.6.0-test5 kernel (with the preemptible kernel option on),
> > using the ice1712 alsa driver (although this also happens in 2.4.21
> > without preemptible kernel).
> >
> > Music plays fine until I do *anything* - changing windows, scrolling,
> > pressing buttons, whatever - when it stutters badly. Scrolling in an
> > anti-aliased terminal is especially fun. However, if I play using XMMS
> > with the realtime priority option, everything's fine, although that has
> > the distinct disadvantage that I have to run it as root.
> >
> > I've tried enabling/disabling ACPI/APM/APIC. The card isn't sharing an
> > IRQ with anything.  It's not a hard drive/IDE related issue, although
> > that's all using DMA anyway.
> >
> > I do have both an AGP and a PCI graphics card installed and in use,
> > although the stuttering happens if I do anything on either. I've found a
> > few references to this problem on google, but no solutions. It works
> > fine on Windows ;).
> >
> > Here's what happens if I try to scroll in gnome-terminal whilst aplaying
> > something:
> >
> > rg@russell:~$ aplay < test
> > Playing raw data 'stdin' : Unsigned 8 bit, Rate 8000 Hz, Mono
> > xrun!!! (at least 869.990 ms long)
> > xrun!!! (at least 21.552 ms long)
> > xrun!!! (at least 17.686 ms long)
> > xrun!!! (at least 16.482 ms long)
> > xrun!!! (at least 17.194 ms long)
> > xrun!!! (at least 17.126 ms long)
> > xrun!!! (at least 14.123 ms long)
> > xrun!!! (at least 13.679 ms long)
> > xrun!!! (at least 12.928 ms long)
> > [...and so on, for another 20 or so lines]
>
> i guess it's a general scheduler issue.
>
> why you face this problem more severly than others:
> the timing on the ice1712 (envy24) chip is quite tight, because it
> always needs 32bit * 10 channels interleaved samples even if you want
> to play a two-channel mp3 file.  more badly, the maximum buffer size
> is limited to 64k byte.  hence, at most, you can get about 0.1 sec for

It's limited to 256kB. And yes, it's only 0.14 sec for 44.1kHz playback.

						Jaroslav

-----
Jaroslav Kysela <perex@xxxxxxx>
Linux Kernel Sound Maintainer
ALSA Project, SuSE Labs
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