Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030303AbWADWZ3 (ORCPT ); Wed, 4 Jan 2006 17:25:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030305AbWADWZ3 (ORCPT ); Wed, 4 Jan 2006 17:25:29 -0500 Received: from dspnet.fr.eu.org ([213.186.44.138]:43787 "EHLO dspnet.fr.eu.org") by vger.kernel.org with ESMTP id S1030303AbWADWZ1 (ORCPT ); Wed, 4 Jan 2006 17:25:27 -0500 Date: Wed, 4 Jan 2006 23:25:17 +0100 From: Olivier Galibert To: Kyle Moffett Cc: Jan Engelhardt , Takashi Iwai , Jesper Juhl , Adrian Bunk , Tomasz Torcz , Alistair John Strachan , Andi Kleen , perex@suse.cz, alsa-devel@alsa-project.org, James@superbug.demon.co.uk, sailer@ife.ee.ethz.ch, linux-sound@vger.kernel.org, zab@zabbo.net, kyle@parisc-linux.org, parisc-linux@lists.parisc-linux.org, jgarzik@pobox.com, Thorsten Knabe , zwane@commfireservices.com, zaitcev@yahoo.com, linux-kernel@vger.kernel.org Subject: Re: [2.6 patch] schedule obsolete OSS drivers for removal Message-ID: <20060104222517.GA55316@dspnet.fr.eu.org> Mail-Followup-To: Olivier Galibert , Kyle Moffett , Jan Engelhardt , Takashi Iwai , Jesper Juhl , Adrian Bunk , Tomasz Torcz , Alistair John Strachan , Andi Kleen , perex@suse.cz, alsa-devel@alsa-project.org, James@superbug.demon.co.uk, sailer@ife.ee.ethz.ch, linux-sound@vger.kernel.org, zab@zabbo.net, kyle@parisc-linux.org, parisc-linux@lists.parisc-linux.org, jgarzik@pobox.com, Thorsten Knabe , zwane@commfireservices.com, zaitcev@yahoo.com, linux-kernel@vger.kernel.org References: <20060103170316.GA12249@dspnet.fr.eu.org> <20060103203732.GF5262@irc.pl> <9a8748490601031256x916bddav794fecdcf263fb55@mail.gmail.com> <20060103215654.GH3831@stusta.de> <9a8748490601031411p17d4417fyffbfee00ca85ac82@mail.gmail.com> <27043632-7EA6-4468-A5D9-7E90725373F3@mac.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <27043632-7EA6-4468-A5D9-7E90725373F3@mac.com> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1522 Lines: 40 On Wed, Jan 04, 2006 at 03:12:33PM -0500, Kyle Moffett wrote: > Software mixing in the kernel probably _IS_ FPU ops in the kernel. > We already do video mixing (think X) in userspace, I see no reason > why audio should be different. Bad comparison. X as it is is so good that if you want something remotely looking like performance you end up with a proprietary kernel module the size of Cleveland. Software mixing in practice could be in the kernel, it's for instance way less complex than say the network stack. I mean, even with an helper thread, it fits in 20-30 lines of kernel code or so. But what happens is that you quickly want much more than that. To give you some examples: - resampling (with a wide array of algorithms with a different cpu usage/result quality mix), especially since a number of chips are 48KHz only. - AC3/DTS encoding for multichannel output on spdif. - spatialisation (virtual or real, depending on the hardware available). - dynamic range compression. So as soon as you build some decent infrastructure to allow for that in userspace, having software mixing specifically in the kernel does not make much sense. I have 3 main problems with ALSA, but using userspace for flexibility is definitively not one of them. OG. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/