Date: Mon, 5 Jul 1999 18:47:45 +0200 (MET DST) From: Luigi Rizzo <luigi@labinfo.iet.unipi.it> To: shocking@prth.pgs.com (Stephen Hocking-Senior Programmer PGS Tensor Perth) Cc: multimedia@freebsd.org Subject: Re: Mods to snd drivers Message-ID: <199907051647.SAA20559@labinfo.iet.unipi.it> In-Reply-To: <199907050525.NAA25530@ariadne.tensor.pgs.com> from "Stephen Hocking-Senior Programmer PGS Tensor Perth" at Jul 5, 99 01:25:15 pm
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Sorry about the late reply...
> I've finnaly moved from my old PAS16 (which I used under the Voxware drivers)
> to a PnP CS4236 clone. This works fine (once I told the BIOS that I *didn't*
> have a PnP OS). However, some niceties that I was used to under the Voxware
> drivers are not there - to wit
>
> a) Setting the queue size on DST_SETFRAGSIZE
this would be rather simple to implement without changing the DMA buffer
size. It would suffice to check, when you write into the buffer, that
you don't exceed the programmed size instead of the full buffer size.
I just got lazy because you can control this by other means eg probing
the queue occupation before writing and doing a more informed data
drop or whatever in userland.
E.g. i think the modified audio_voxware.cc in vat does something like
this (maybe the code is commented out, but i am almost sure it is
there).
> b) DSP_{SET,GET}TRIGGER
ok, this is missing.
> c) Doing the mmap thing with an ioctl.
the latter is there, just of no use without trigger support!
> It's obvious which application the last two are for 8^). However, a) is useful
> for dropping the latency for things like network telephones, which the
> full-duplex nature of the card & drivers is otherwise suited to. I see that
see above. this is certainly a useful thing, but can be done without
setting the buffer size.
cheers
luigi
-----------------------------------+-------------------------------------
Luigi RIZZO, luigi@iet.unipi.it . Dip. di Ing. dell'Informazione
http://www.iet.unipi.it/~luigi/ . Universita` di Pisa
TEL/FAX: +39-050-568.533/522 . via Diotisalvi 2, 56126 PISA (Italy)
http://www.iet.unipi.it/~luigi/ngc99/
==== First International Workshop on Networked Group Communication ====
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