From mboxrd@z Thu Jan 1 00:00:00 1970 From: Takashi Iwai Subject: Re: question about minimum latency. (jack) how to calculate it? Date: Tue, 23 Nov 2004 18:11:42 +0100 Message-ID: References: <200411220715.03369.pilo.c@wanadoo.fr> Mime-Version: 1.0 (generated by SEMI 1.14.5 - "Awara-Onsen") Content-Type: text/plain; charset=US-ASCII Return-path: In-Reply-To: <200411220715.03369.pilo.c@wanadoo.fr> Sender: alsa-devel-admin@lists.sourceforge.net Errors-To: alsa-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: pilo.c@wanadoo.fr Cc: alsa-devel@lists.sourceforge.net List-Id: alsa-devel@alsa-project.org At Mon, 22 Nov 2004 07:15:02 +0100, Pierre-Laurent CHAMBERT wrote: > > Hi! > > I would like to know how I can improve latency on digi32/8 driver. > The card has got a buffer of 128Ko, and block size per interrupt is 8Ko (so it > makes 16 interrupt for the whole buffer). When I start jack I can use only > setup 256 frame/periods (32bits, 8channel in adat mode) and 16 periods/ > buffer. So this mean I can only have 80ms of latency?!? It's not possible to > use less than 16 periods? > I mean, a sound is recorded, the card send an interupt so the sound just > recorded can not be read in the memory, and write back in memory 2 interrupts > after? > Maybe I miss something here, I already try to change number of periods/buffer > in the driver, but of course with no luck. > So if the buffer size (128Ko here) and block size (8Ko) are always the same it > cannot get a lower latency? The latest CVS version of JACK includes my patch to improve the latency on the cards like yours. Please give a try. Takashi ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://productguide.itmanagersjournal.com/