From mboxrd@z Thu Jan 1 00:00:00 1970 From: Clemens Ladisch Subject: Re: Fast Track Ultra latency and new streaming logic. Date: Thu, 03 May 2012 17:21:52 +0200 Message-ID: <4FA2A290.6010301@ladisch.de> References: <4FA2927C.1010501@ladisch.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from out4-smtp.messagingengine.com (out4-smtp.messagingengine.com [66.111.4.28]) by alsa0.perex.cz (Postfix) with ESMTP id D5D5B10448A for ; Thu, 3 May 2012 17:17:45 +0200 (CEST) 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: Felix Homann Cc: alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org Felix Homann wrote: > 2012/5/3 Clemens Ladisch : >> USB playback also adds further latency by queueing the packets; the >> number of packets can be seen under "URBs" in /proc/asound/card?/stream0. >> (There are 1000/8000 packets per second at full/high speed.) > > I'm getting "URBs = 2 [ 5 6 ]" for playback and "URBs = 8 [ 8 8 8 8 > 8 8 8 8 ]" for capture with the "old" streaming logic. What does it > mean? The queue length is 5+6 = 11 packets; at high speed, that's 11 / 8 kHz = 1.4 ms. Regards, Clemens