From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jack O'Quin" Subject: Re: Lowest latency: JACK, or ALSA directly? Date: 12 Nov 2004 11:19:25 -0600 Message-ID: <87k6srx9wi.fsf@sulphur.joq.us> References: <20041111144152.GA12443@stud.ntnu.no> <87mzxozahr.fsf@sulphur.joq.us> <20041112090416.GA3167@stud.ntnu.no> <87oei3xbly.fsf@sulphur.joq.us> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: In-Reply-To: Sender: alsa-devel-admin@lists.sourceforge.net Errors-To: alsa-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: Takashi Iwai Cc: =?iso-8859-1?q?Asbj=F8rn_S=E6b=F8?= , alsa-devel@lists.sourceforge.net List-Id: alsa-devel@alsa-project.org Takashi Iwai writes: > At 12 Nov 2004 10:42:33 -0600, > Jack O'Quin wrote: > > The sound card generates an interrupt at the end of each period. This > > determines the input latency. The hardware buffer holds multiple > > periods (you need at least two). Its size determines the maximum > > output latency. With JACK, there's not much reason to use more than > > two or three periods, unless you're running without realtime > > privileges. > > Regarding JACK's latency: can JACK handle more than two periods with > the minimal latency? That is, keeping only two periods active (the > current playing and the next periods), you can achieve the same > latency even if the buffer consists of more than two periods. > > I'm asking this because some boards (e.g. RME32/96) have the fixed > buffer size, and can't take the configuration as two periods per > buffer. IIRC, JACK fills all the buffer at the first sequence, and > this results in the higher latency than necessary. > > Correct me if I'm wrong. I believe you are correct about this. You probably understand it better than I do. :-) Is this something we could fix in JACK's ALSA driver backend? -- joq ------------------------------------------------------- This SF.Net email is sponsored by: Sybase ASE Linux Express Edition - download now for FREE LinuxWorld Reader's Choice Award Winner for best database on Linux. http://ads.osdn.com/?ad_id=5588&alloc_id=12065&op=click