From mboxrd@z Thu Jan 1 00:00:00 1970 From: Takashi Iwai Subject: Re: Re: [Alsa-user] AD1985 full-duplex(?) Date: Mon, 23 Aug 2004 17:30:06 +0200 Sender: alsa-devel-admin@lists.sourceforge.net Message-ID: References: <1092842830.13603.3.camel@localhost.localdomain> <20040818181350.2b38e875@mango.fruits.de> <20040818201535.1f49a128@mango.fruits.de> <4129D6A2.7020801@pg.gda.pl> Mime-Version: 1.0 (generated by SEMI 1.14.5 - "Awara-Onsen") Content-Type: text/plain; charset=ISO-8859-2 Content-Transfer-Encoding: quoted-printable Return-path: Received: from Cantor.suse.de (cantor.suse.de [195.135.220.2]) by alsa.alsa-project.org (ALSA's E-mail Delivery System) with ESMTP id 7E38C2D7 for ; Mon, 23 Aug 2004 17:33:05 +0200 (MEST) In-Reply-To: <4129D6A2.7020801@pg.gda.pl> Errors-To: alsa-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: Adam =?ISO-8859-2?Q?Tla=B3ka?= Cc: alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org At Mon, 23 Aug 2004 13:36:02 +0200, Adam Tla=B3ka wrote: >=20 > > On Thu, 19 Aug 2004, Takashi Iwai wrote: > >>Can "network sound device" work with the mmap, too? > > I think yes, it can, but the real output will be more delayd. So, it = won't=20 > > be much useable for the strict real-time applications. > But old quake and new quake3 and some OSS apps use mmap mode for better= =20 > timing and accurate mixing I doubt it. Mmap doesn't provide better nor accurate "timing" although it provides more efficient data transfer method. The accuracy depends on the fineness of DMA interrupts and the scheduler latency. I don't see so big requirement of mmap in this regard. If you need a free-running ring buffer, you can do it simply by setting the proper stop_threshold for disabling XRUN detection. The perfomance win by mmap is far little in comparison with computations of mixing and effects. Hence, what I see here is only the demand of "compatibility". From the performance perspective, there is no reason to force mmap. Note that I don't mention here about apps with high bandwidth like HDR but apps with normal 16bit/48k sounds with at most 6 voices in the background. Also, I don't mean that network system can provide as good response as the normal system. What I mean is that the discussion of latency should be indepdent from necessity of mmap implementaion. Takashi ------------------------------------------------------- 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