From mboxrd@z Thu Jan  1 00:00:00 1970
From: Takashi Iwai <tiwai@suse.de>
Subject: Re: status pointer's problem with dmix.
Date: Wed, 17 Sep 2003 21:10:42 +0200
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To: James Courtier-Dutton <James@superbug.demon.co.uk>
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At Wed, 17 Sep 2003 20:01:36 +0100,
James Courtier-Dutton wrote:
> 
> Takashi Iwai wrote:
> > At Wed, 17 Sep 2003 19:33:29 +0100,
> > James Courtier-Dutton wrote:
> > 
> >>Output from sending stereo sound to the "dmix" device.
> >>bash-2.05b# cat status
> >>state: RUNNING
> >>trigger_time: 1063822024.640173000
> >>tstamp      : 1063822060.456968000
> >>delay       : -1719463
> >>avail       : 1731463
> >>avail_max   : 1731463
> >>-----
> >>hw_ptr      : 1719463
> >>appl_ptr    : 0
> >>bash-2.05b#
> >>
> >>Output from sending stereo sound to the "front" device.
> >>bash-2.05b# cat status
> >>state: RUNNING
> >>trigger_time: 1063823309.038609000
> >>tstamp      : 1063823320.869677000
> >>delay       : 14161
> >>avail       : 2223
> >>avail_max   : 3586
> >>-----
> >>hw_ptr      : 567983
> >>appl_ptr    : 582144
> >>
> >>As you can see, the "front" device acts correctly, with all the pointers 
> >>acting as they should.
> >>But with "dmix", all the pointers are wrong.
> >>This is particularly problematic for me, as I need a properly 
> >>functioning "delay" value for my application.
> >>
> >>This is using alsa from 2.6test5 kernel.
> > 
> > 
> > is it through the rate plugin?
> > there was a bug about rate plugin together with dmix, which was fixed
> > recently on cvs.
> > 
> > 
> > Takashi
> > 
> > 
> How do I tell if it is using the "rate" plugin?
> I am outputing a single stereo signal at 48khz, 16 bits.
> Where do I configure the rate that dmix works at natively?

at best you can dump the pcm status to the error log from your app.
to check the rate conversion, comparing the status in
/proc/asound/card0/pcm0p/sub0/hw_params would be enough, though.
if the hardware uses a different sample rate, surely the rate plugin
is working.

anyway, if you're using the cvs version of yesterday/today, it must be
ok.


Takashi


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