From mboxrd@z Thu Jan 1 00:00:00 1970 From: Florian Schmidt Subject: Re: [Alsa-user] AD1985 full-duplex(?) Date: Wed, 18 Aug 2004 20:15:35 +0200 Sender: alsa-devel-admin@lists.sourceforge.net Message-ID: <20040818201535.1f49a128@mango.fruits.de> References: <1092842830.13603.3.camel@localhost.localdomain> <20040818181350.2b38e875@mango.fruits.de> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from mail.gmx.net (mail.gmx.de [213.165.64.20]) by alsa.alsa-project.org (ALSA's E-mail Delivery System) with SMTP id D9291254 for ; Wed, 18 Aug 2004 20:04:40 +0200 (MEST) In-Reply-To: Errors-To: alsa-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: Jaroslav Kysela Cc: Shaya Potter , Clemens Ladisch , Mauro Romano Trajber , ALSA development List-Id: alsa-devel@alsa-project.org On Wed, 18 Aug 2004 19:37:16 +0200 (CEST) Jaroslav Kysela wrote: > > I know how much the ALSA developers favor the modular approach > > having sw mixing done in userspace. I think this is suboptimal for > > several reasons: > > > > 1] the scheduling problems you mentioned > > No, the actual dmix implementation does not use mutexes, so > rescheduling is not required. I see.. > > > 2] legacy OSS apps need to be run via aoss which still stinks for > > many apps > > It's really problem, but it's problem that we need a compatibility > with broken API (no library at the initial stage of design, so we > cannot emulate OSS API directly without using hacks). > > Also at this time, nobody helped me to improve the liboss (aoss) code > in some serious way. I ask why? Nobody uses it? Nobody wants this > layer fully functional? Hmm, you went on to make a wrapper for which the apps need to be changed at source code level. This is an option which is often not available [old games with makers who are broke whatever, closed source app where the vendor just refuses to fix it at all, etc.]. This is why i don't have any interest in improving it. I do have interest in improving aoss though wrt the traditional LD_PRELOAD hack.. But fixing the mmap issue was over my head [sorry], so i didn't go after it further. > > I have another idea how we can solve this issue - a network sound > driver, but this will add the scheduling problems including the > throughput of the network layer, of course. > > > 3] the user has to edit configuration files, which is a showstopper > > for newbies and people who have never had to follow a rigorous > > syntax. > > It's not a goal. In 90% of cases, you may simply use plug:dmix device > which is already defined in the global configuration files. yes, you're right. Btw: i also think there needs to be a predefined asym device which makes fullduplex access available for nultiple apps, too.. > > > I would suggest writing another "dummy" soundcard module which would > > sit "ontop" of the normal alsa driver and which does nothing but > > provide sw mixing access [including the needed resampling and > > mixing]. > > It's not easy task and again, do we need to code it in the kernel > space? Benefits? Target users? > > I think that we should provide the functionality (mixing) for all > APIs, but the latency issues which mixing might invoke are not a > serious problem. It's similar to graphics cards. You'll get better > results with an accelerator (in case of sound with hardware having the > mixing capability). > Yes. I just am not sure what is easier: a] fixing aoss to support all legacy oss apps [even those which cannot be changed at source code level] b] create a kernel module like the beforementioned which would just eliminate the issue for most users since they can just use the kernel level oss emu.. I really am not sure anymore. What do you think? Flo -- Palimm Palimm! http://affenbande.org/~tapas/ ------------------------------------------------------- SF.Net email is sponsored by Shop4tech.com-Lowest price on Blank Media 100pk Sonic DVD-R 4x for only $29 -100pk Sonic DVD+R for only $33 Save 50% off Retail on Ink & Toner - Free Shipping and Free Gift. http://www.shop4tech.com/z/Inkjet_Cartridges/9_108_r285