From mboxrd@z Thu Jan 1 00:00:00 1970 From: Clemens Ladisch Subject: Re: regarding setting of fragment size in usbaudio driver Date: Mon, 13 Dec 2010 10:04:29 +0100 Message-ID: <4D05E19D.7010405@ladisch.de> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from out3.smtp.messagingengine.com (out3.smtp.messagingengine.com [66.111.4.27]) by alsa0.perex.cz (Postfix) with ESMTP id 44D1210381A for ; Mon, 13 Dec 2010 10:01:42 +0100 (CET) In-Reply-To: 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: Amit Nagal Cc: alsa-user@lists.sourceforge.net, alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org Amit Nagal wrote: > i am using a OSS based usbaudio application for usb audio streaming . > > my usb audio device is capture only device . > > i want to set the fragment size of usbaudio alsa driver to reduce > latency problem coming in my application . > > currently even if my application reads 4k data from userspace , i > observed driver will buffer for 100 ms data ( period size data )= 16 k > at 44100 frquency > > and after driver reads 16k data , read call will return with 4k data > . so read() call remains blocked for 100ms which is causing some > latency problem . There is no extra buffer in the driver. There seems to be something wrong with your algorithm. Does recording with the arecord tool work? Regards, Clemens