Re: how to precisely align the audio output of a Jack MIDI client in Ardour?

Am Freitag, 10. November 2017, 00:21:19 CET schrieben Sie:
> What version of Ardour is involved?
I first noticed this in Ardour 5.11.0 (built from unmodified git sources, tag 
"5.11"), but I didn't investigate it in detail in earlier versions, so I can't 
tell when this issue appeared. I'll have a look at Ardour 5.12 tomorrow.

	Kind regards,
		Markus

> 
> On Thu, Nov 9, 2017 at 5:56 PM, Markus Grabner <[email protected]> wrote:
> >         Hi!
> > 
> > I recently made some effort to measure the latencies of my audio equipment
> > to
> > get perfectly aligned capturing and playback with Ardour (version 5.11),
> > and
> > so far it worked well. However, I failed at a task which I thought should
> > be
> > one of the easiest. I have a Jack client which takes MIDI input and
> > produces
> > audio output (actually LinuxSampler, but the same issue can be
> > demonstrated
> > with the attached minimal Jack client and Ardour session). When recording
> > the
> > audio output of the Jack MIDI client into an Ardour audio track, I noticed
> > that the signal is delayed by one Jack period, regardless of the latency
> > set
> > by the client for its ports. When I change the alignment mode of the audio
> > track to which I'm recording from "Automatic (Capture Time)" to "Align
> > With
> > Existing Material", the signal is recorded too early by (m-1)*n+o frames,
> > where m is the number of periods, n the frame size, and o the output
> > latency
> > of the Jack server. Latency of the Jack MIDI client does have an effect
> > now,
> > but only shifts the signal even earlier in time.
> > 
> > To summarize:
> > *) In "Align With Capture Time" mode, the audio signal created by the Jack
> > MIDI client is too late, and latency settings of the Jack MIDI client are
> > ignored.
> > *) In "Align With Existing Material" mode, the audio signal created by the
> > Jack MIDI client is too early, and can only be shifted to an even earlier
> > time
> > by setting the latency of the Jack MIDI client.
> > 
> > So what is the recommended way to get frame-accurate recordings of the
> > audio
> > output of a Jack MIDI client receiving input from an Ardour MIDI track
> > (aside
> > from manually nudging the recorded regions)?
> > 
> >         Thanks & kind regards,
> >         
> >                 Markus
> > 
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