From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Rigg Subject: Re: Enabling in-kernel synch for M-Audio boards Date: Tue, 18 Sep 2007 07:57:23 +0100 Message-ID: <20070918065723.GA2512@localhost> References: <46EE555B.9000700@alice.it> <20070917194403.GA3655@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail3.uklinux.net (mail3.uklinux.net [80.84.72.33]) by alsa0.perex.cz (Postfix) with ESMTP id 91D5724450 for ; Tue, 18 Sep 2007 08:52:41 +0200 (CEST) Content-Disposition: inline In-Reply-To: <20070917194403.GA3655@localhost> 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: Ludovico Verducci Cc: alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org On Mon, Sep 17, 2007 at 08:44:03PM +0100, John Rigg wrote: > On Mon, Sep 17, 2007 at 12:22:19PM +0200, Ludovico Verducci wrote: > > Hello all! > > > > I'm developing a complex multichannel audio distribution system where > > multiple linux boxes will stream audio data over ethernet and then > > should play audio at sample level resolution synchronization. The boxes > > clocks are synchronized over ethernet using PTP. > > I need to keep in synch the audio board's clocks and I can't use an > > external wordclock nor s/pdif. > > Won't this cause serious clock jitter problems? I don't see how the > PCI bus can deliver precise enough timing, considering how much other > data it has to handle. And I can't see any way that the clocks can be synced to sample accuracy over ethernet. That's what external word clocks are for. Even with a word clock I suspect that the latency of the ethernet connection would be too high to allow sample accurate sync of the audio. John