From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Courtier-Dutton Subject: Re: Disabling buffer fill level preprocessing by ALSA Date: Mon, 07 Jan 2008 18:55:23 +0000 Message-ID: <4782759B.5000208@superbug.co.uk> References: <20071231171226.GA17953@tango.0pointer.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from anchor-post-34.mail.demon.net (anchor-post-34.mail.demon.net [194.217.242.92]) by alsa0.perex.cz (Postfix) with ESMTP id B54282497E for ; Mon, 7 Jan 2008 19:55:24 +0100 (CET) Received: from superbug.demon.co.uk ([80.176.146.252] helo=[192.168.0.10]) by anchor-post-34.mail.demon.net with esmtp (Exim 4.67) id 1JBx88-000Khz-Dm for alsa-devel@alsa-project.org; Mon, 07 Jan 2008 18:55:24 +0000 In-Reply-To: <20071231171226.GA17953@tango.0pointer.de> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: alsa-devel-bounces@alsa-project.org Errors-To: alsa-devel-bounces@alsa-project.org To: ALSA Development Mailing List List-Id: alsa-devel@alsa-project.org Lennart Poettering wrote: > Hi! > > In PulseAudio I want to schedule on my own when I need to write audio > data into the device and when not. To achieve that I want to be > notified via poll() whenever a period boundary is passed (i.e. when an > IRQ happens), but only then. That's different from the usual mode > where you are notified via poll() whether there is space in the > playback buffer that needs to be filled up. > > On OSS the mmap() mode enables a mode like I described above. After > enabling mmap() the application can decide by itself what it considers > full and what empty in the dma buffer, and use GETOPTR to query the > playback position. poll() on the OSS fd will directly reflect the > sound card IRQs and is not influenced if you ever wrote data to device > or not. > > I assume that I can enable a mode like that with one of the SW > params. But quite frankly the docs for it are not enlighening at all. > > Lennart > What would you want to do that for? Surely you just want to be told "I need X samples now please", and that is what the current alsa poll/callback method does. James