Re: [Jack-Devel] is this latency coming from ALSA, jack, or ardour?

On Wed, April 13, 2011 12:30 pm, Nedko Arnaudov wrote:
> With a really good hardware/software setup you should
> be able to get less than a milisecond latency.
...
> The analog-digital (and vice versa) conversion
> always results in a latency. So it is not issue with ALSA,
> jack or Ardour.  It is how digital audio works.

Sorry, I realized I was not very clear in what I was really asking.

Ardour with the latest jack can now request the latency from each jack
connection, and correct appropriately when lining up multiple tracks.  My
understanding of that capability is that when you record one track, play
that track back and record a second track synchronized with the first,
Ardour should be able to calculate the playback latency of the first
track, the input latency of the hardware used for the second track, and
adjust the relative timing to null out the latency, which is of course
always present with digital audio.

My question was really why was the latency not fully compensated
correctly?  Either Ardour is still not compensating correctly, or jack is
not reporting the latency correctly to Ardour for compensation, or ALSA is
not reporting the correct latency to jack, which will of course make every
later calculation by jack and Ardour incorrect by the amount of error in
the ALSA report.

Or my understanding of the capabilities of Ardour3 along with latest JACK
is in error.

The latter means I need to plan on manual adjustment of track offsets, one
of the first three implies a bug report, but to one of three different
places depending on the source of the error.  My hunch at the moment is
ALSA, but that is why I am experimenting, to determine that empirically.

-- 
Chris Caudle

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