From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lee Revell Subject: Re: emu10k1 latency / capture period Date: Fri, 18 Jun 2004 15:39:40 -0400 Sender: alsa-devel-admin@lists.sourceforge.net Message-ID: <40D344FC.8070804@joe-job.com> References: <40D1E4E7.8000704@joe-job.com> <200406172326.i5HNQkQV017899@dhin.linuxaudiosystems.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Errors-To: alsa-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: Takashi Iwai Cc: Paul Davis , Alsa-devel@lists.sourceforge.net, pzad@pobox.sk List-Id: alsa-devel@alsa-project.org Takashi Iwai wrote: > At Thu, 17 Jun 2004 19:26:46 -0400, > Paul Davis wrote: > >>>To reiterate the situation: currently the ASIO drivers for this card >>>provide an order of magnitude >>>better latency than the ALSA driver. I am constantly hearing claims >>>that ALSA is superior to ASIO, >>>but no one can tell me why the ALSA drivers for this *very* common >>>device provide 5-10x worse latency >>>than the ASIO drivers. >>> >>>As I see it, this is a glaring deficiency. >> >>as a disinterested observer, i would just note that by my >>understanding, Creative have not released all the necessary >>programming information on the emu10k1. i suspect that whatever is >>necessary to get the period size down to the levels the ASIO driver(s) >>are using is in the information that they will not release without an >>NDA. > > > It might be. But my guess is that ASIO uses the playback interrupt > for capture, too. > Thank you, this was the idea that I had, to use the playback interrupt to drive the capture. I was hoping someone with in-depth knowledge of ALSA would agree. Is there another ALSA driver that provides an example of this kind of design? I am pretty new to hacking device drivers and an example would be helpful, if one is available. P.S. Here is some background for people who are familiar with the emu10k1 hardware but don't use Windows or the kX drivers, I think there are a few on this list: The kX ASIO driver maps each FXBus channel onto an ASIO input and output port. In order to do low latency/multichannel recording, you have to use the DSP manager to connect one of the physical inputs or outputs to an FXBus channel, then your ASIO app can read or write to that channel. I think we only need to be concerned with the FXBus capture/playback device. Lee ------------------------------------------------------- This SF.Net email is sponsored by The 2004 JavaOne(SM) Conference Learn from the experts at JavaOne(SM), Sun's Worldwide Java Developer Conference, June 28 - July 1 at the Moscone Center in San Francisco, CA REGISTER AND SAVE! http://java.sun.com/javaone/sf Priority Code NWMGYKND