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

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What version of Ardour is involved?

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
>
> _______________________________________________
> ardour-dev mailing list
> [email protected]
> http://lists.ardour.org/listinfo.cgi/ardour-dev-ardour.org
>
>

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<div dir=3D"ltr"><div class=3D"gmail_default" style=3D"font-family:arial,he=
lvetica,sans-serif">What version of Ardour is involved?<br></div></div><div=
 class=3D"gmail_extra"><br><div class=3D"gmail_quote">On Thu, Nov 9, 2017 a=
t 5:56 PM, Markus Grabner <span dir=3D"ltr">&lt;<a href=3D"mailto:mg.2849@w=
42.at" target=3D"_blank">[email protected]</a>&gt;</span> wrote:<br><blockquot=
e class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc sol=
id;padding-left:1ex">=C2=A0 =C2=A0 =C2=A0 =C2=A0 Hi!<br>
<br>
I recently made some effort to measure the latencies of my audio equipment =
to<br>
get perfectly aligned capturing and playback with Ardour (version 5.11), an=
d<br>
so far it worked well. However, I failed at a task which I thought should b=
e<br>
one of the easiest. I have a Jack client which takes MIDI input and produce=
s<br>
audio output (actually LinuxSampler, but the same issue can be demonstrated=
<br>
with the attached minimal Jack client and Ardour session). When recording t=
he<br>
audio output of the Jack MIDI client into an Ardour audio track, I noticed<=
br>
that the signal is delayed by one Jack period, regardless of the latency se=
t<br>
by the client for its ports. When I change the alignment mode of the audio<=
br>
track to which I&#39;m recording from &quot;Automatic (Capture Time)&quot; =
to &quot;Align With<br>
Existing Material&quot;, the signal is recorded too early by (m-1)*n+o fram=
es,<br>
where m is the number of periods, n the frame size, and o the output latenc=
y<br>
of the Jack server. Latency of the Jack MIDI client does have an effect now=
,<br>
but only shifts the signal even earlier in time.<br>
<br>
To summarize:<br>
*) In &quot;Align With Capture Time&quot; mode, the audio signal created by=
 the Jack<br>
MIDI client is too late, and latency settings of the Jack MIDI client are<b=
r>
ignored.<br>
*) In &quot;Align With Existing Material&quot; mode, the audio signal creat=
ed by the<br>
Jack MIDI client is too early, and can only be shifted to an even earlier t=
ime<br>
by setting the latency of the Jack MIDI client.<br>
<br>
So what is the recommended way to get frame-accurate recordings of the audi=
o<br>
output of a Jack MIDI client receiving input from an Ardour MIDI track (asi=
de<br>
from manually nudging the recorded regions)?<br>
<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 Thanks &amp; kind regards,<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 Markus<br>
<br>______________________________<wbr>_________________<br>
ardour-dev mailing list<br>
<a href=3D"mailto:[email protected]">[email protected]<=
/a><br>
<a href=3D"http://lists.ardour.org/listinfo.cgi/ardour-dev-ardour.org" rel=
=3D"noreferrer" target=3D"_blank">http://lists.ardour.org/<wbr>listinfo.cgi=
/ardour-dev-<wbr>ardour.org</a><br>
<br></blockquote></div><br></div>

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