Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757404Ab1CBUBP (ORCPT ); Wed, 2 Mar 2011 15:01:15 -0500 Received: from smtp.getmail.no ([84.208.15.66]:38978 "EHLO smtp.getmail.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755982Ab1CBUBO (ORCPT ); Wed, 2 Mar 2011 15:01:14 -0500 MIME-version: 1.0 Content-transfer-encoding: 8BIT Content-type: text/plain; charset=iso-8859-15; format=flowed; delsp=yes References: <4D6CD10E.3050805@ladisch.de> <4D6DF1B2.2010500@ladisch.de> Subject: Re: Possible bug, with extreme low latency audio. To: linux-kernel@vger.kernel.org, clemens@ladisch.de Date: Wed, 02 Mar 2011 21:01:11 +0100 From: Uwaysi Bin Kareem Message-id: In-reply-to: <4D6DF1B2.2010500@ladisch.de> User-Agent: Opera Mail/11.01 (Linux) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1422 Lines: 35 On Wed, 02 Mar 2011 08:28:50 +0100, Clemens Ladisch wrote: > Uwaysi Bin Kareem wrote: >> The other is a firewire device (Konnekt24d using FFADO, running on the >> old >> firewire stack). >> The firewire device actually plays nicely without much buffer underruns >> down to 0.363 ms latency (8x2 @ 44.1k). > > FireWire packets are sent every 125 ?s; for audio, every packet contains > either zero or eight samples, and the proportion of data and no-data > packets is adjusted so that the overall rate is 44100 samples per > second. So 8x2 is the theoretical minimum. > >> However it seems to choke at 8x2 @ 96k. > > At sample rates above 48 kHz, there are 16 samples per packet (and above > 96 kHz, 32). It is not possible to use 8x2 at 96 kHz, and FFADO should > not have allowed you to try it; please file a bug there: > (requires a login). > Ok, I am hitting the hardware limits. I'll inform FFADO crew about this. There are probably more bound to hit this limit, as lowlatency operation with Linux, is getting this good. A good error msg with the above information, would be good. Best Regards, Uwaysi. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/