xrun in arecord, ice1714

xrun in arecord, ice1714

[Mark Ziegler]

Hi,

I've sent this mail already to the alsa-user formum, but nobody answered. I 
don't know, my be the questions are too stupid, too difficult or just too 
trivial. Sorry for bothering you, but I really think its something to talk a 
little bit.

Hopefully an alsa developer has an answer:


I've got 2 questions:

1.) I want to record the digital input from my ice1714 based terratec card. I
found here the advice to write the following ~/,asoundrc:

pcm.ice_spdif {
                type plug
                ttable.0.8 1
                ttable.1.9 1
                slave.pcm {
                        type hw
                        card 1
                        device 0
                }
        }

Then I started arecord -f cd -Dice_spdif test.wav

Ok, works fine. But I figgured out, that even a 48kHz sampled song will be
resampled to 44.1kHz by the alsa drivers. I understood, with the option -f
dat I can sample 48kHz. But I would be more lucky, if I cound get the raw
data without resampling by the alsa drivers. I mean, it might be, that my DAT
Player gives only 44099 Hz. Does anybody know how to modify the .asoundrc to
switch off the resampling feature?

2.) arecord reported a lot of xruns. I also tried to run arecord from the
commandline and I switched off the x-server, I worked on a fresh booted linux
system, I played with the arecord option -B from 10000 to 3000000 (I don't
care about latency), but the xruns didn't disapear. And when playing back the
samples, the breaks don't sound very good. I found here in the newsgroup the
hint to use

ecasound -r -z:db -z:intbuf -f:s32_le,12,44100 -i alsa,hw:1 -f:s32_le,2,44100
-o test.wav

under root, but usually my system hangs complete after starting ecasound.
 Only once it worked and it also reported that some data are lost.

So far, now my question: Can I do something against the problem, or do I have
to wait for newer alsa-releases or is it more a linux kernel problem? Or is
the problem, that my IDE-drives are buffered in memory, and sometime huge
buffers are written back to the harddisk and the alsa driver doesn't get time
to write out his buffer? Is it more a problem of the userspace (arecord) or
of the alsa-driver?
Or can anybody explain the problem roughly? I think my 2 GHz processor should
be completely bored by transporting 44.1kHz * 2 * 16 / 8  = 176400 Bytes/s
from the sound card to the IDE disk.

For any advice I'm lucky


  Mark


My system:
Software
Suse linux-kernel 2.4.19,
Alsa 0.9 RC5

Hardware
Terratec Soundcard EWX 24/96
Athlon XP 2000



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Re: xrun in arecord, ice1714

[Kai Vehmanen]

On Tue, 19 Nov 2002, Mark Ziegler wrote:

> ecasound -r -z:db -z:intbuf -f:s32_le,12,44100 -i alsa,hw:1 -f:s32_le,2,44100
> -o test.wav
[...]
> under root, but usually my system hangs complete after starting ecasound.
>  Only once it worked and it also reported that some data are lost.

How about if you start as non-root and without the -r? It should still 
be relatively stable due to the -z:db (disk buffering) and -z:intbuf 
(soundcard buffering) options. If this fails, I'd be interested in 
seeing the exact error messages printed by ecasound.

> the problem, that my IDE-drives are buffered in memory, and sometime huge
> buffers are written back to the harddisk and the alsa driver doesn't get time
> to write out his buffer? Is it more a problem of the userspace (arecord) or
> of the alsa-driver?

Make sure you have DMA enabled for disk i/o. See for instance
the article at http://linux.oreillynet.com/lpt/a/467 

> Or can anybody explain the problem roughly? I think my 2 GHz processor should
> be completely bored by transporting 44.1kHz * 2 * 16 / 8  = 176400 Bytes/s
> from the sound card to the IDE disk.

Yep, definitely something goes badly wrong.

--
 http://www.eca.cx
 Audio software for Linux!



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