Re: Lowest latency: JACK, or ALSA directly?

["Jack O'Quin" <joq@io.com>]

Takashi Iwai <tiwai@suse.de> 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


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