From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Courtier-Dutton Subject: Re: IO streams sync Date: Tue, 20 Jun 2006 21:18:22 +0100 Message-ID: <4498580E.3010902@superbug.co.uk> References: <4497D028.5060604@openstudionetworks.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4497D028.5060604@openstudionetworks.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: alsa-devel-bounces@lists.sourceforge.net Errors-To: alsa-devel-bounces@lists.sourceforge.net To: alejandro Cc: alsa-devel@lists.sourceforge.net List-Id: alsa-devel@alsa-project.org alejandro wrote: >> > > Lee and James, > > It is not possible to sync two interfaces if we don't have timestamped > frame numbering (UST/MSC pairs). That means that we need to know, from a > common clock, the time at which a (numbered) frame will be output or was > input from a jack. Current time is not usable, because obviously there > is an unknown delay between function calls. If the system is not able to > produce timestamp/frame count pairs, there is no possibility to sync > audio streams or audio to video streams. I have looked at JACK, and the > situation is the same as with the ALSA API. > > There are cards in the market with such timestamped operations supported > in the hardware and proprietary APIs, but is there a way to accessing > these operations from ALSA or JACK? > > Thank you, > > Alejandro > > I think you are wrong. Just take a look at xine playing a DVD. The audio and video are in perfect sync. It can be done with the current API. James