From owner-freebsd-multimedia Fri Mar 31 16:24:25 2000 Delivered-To: freebsd-multimedia@freebsd.org Received: from hurricane.columbus.rr.com (m5.columbus.rr.com [204.210.252.249]) by hub.freebsd.org (Postfix) with ESMTP id 7830437B6A1 for ; Fri, 31 Mar 2000 16:24:22 -0800 (PST) (envelope-from caa@columbus.rr.com) Received: from columbus.rr.com ([204.210.243.142]) by hurricane.columbus.rr.com (Post.Office MTA v3.5.3 release 223 ID# 0-53939U80000L80000S0V35) with ESMTP id com; Fri, 31 Mar 2000 19:24:26 -0500 Received: (from caa@localhost) by columbus.rr.com (8.9.3/8.9.3) id TAA13355; Fri, 31 Mar 2000 19:24:18 -0500 (EST) (envelope-from caa) Date: Fri, 31 Mar 2000 19:24:18 -0500 From: "Charles Anderson" To: Martin Cracauer Cc: gandalf@vilnya.demon.co.uk, freebsd-multimedia@FreeBSD.ORG Subject: Re: newpcm secondary dma buffer - why? Message-ID: <20000331192418.B13072@midgard.dhs.org> References: <20000331220131.A95404@cons.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 1.0i In-Reply-To: <20000331220131.A95404@cons.org>; from cracauer@cons.org on Fri, Mar 31, 2000 at 10:01:32PM +0200 Sender: owner-freebsd-multimedia@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org I'd like to know why too, it went in mid December, and before that mmap actually worked. I know I had drivers from 12/19/1999 that did mmap'ed sound out to /dev/dsp. -Charlie On Fri, Mar 31, 2000 at 10:01:32PM +0200, Martin Cracauer wrote: > Cameron, multimedia folks, > > could you explain why the newpcm driver uses a secondary buffer to > collect data before it transmits it to the soundcard? > > struct _pcm_channel { > [...] > snd_dbuf buffer2nd; > }; > > Please don't say "it does buffering", I assume that :-) But so far > I've been under the impression that such things are unneeded in > today's soundcards and that it is extremly hard to get the mmap API to > work with such a construction in between. > > Thanks > Martin > -- > %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% > Martin Cracauer http://www.cons.org/cracauer/ > BSD User Group Hamburg, Germany http://www.bsdhh.org/ > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-multimedia" in the body of the message -- Charles Anderson caa@columbus.rr.com No quote, no nothin' To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-multimedia" in the body of the message