[Ardour-Users] Sync between internal and external sources

[Christopher]

Brett nailed it.. but Mark G. was on the right track..

I've pondered this same situation as well.  It boils down to your JACK setup
and the resulting latency from A>D conversion on your input (the bass).

Hydrogen is working in the digital realm until it's processed by your sound
card to the analog output, so latency is minimal on it's output, or even
when sending it to Ardour..

But your bass track (while recording) has to go through the A>D conversion
which will add some latency (once again, depending on your JACK setup and
sound card) and then also even more latency for the D>A process if you are
trying to monitor it through software as you play. (software monitoring vs
hardware monitoring is another story)
Granted, the latency from the SW monitoring isn't affecting what you are
recording, just what you hear (which can in turn affect your rhythm while
playing, making things seem to be out of sync when you play it back)

If you are using hardware monitoring (or just using a bass amp before the
input to the soundcard and not monitoring it on the DAW at all) then the
second set of latency shouldn't be an issue and your recorded bass track
should only be out of sync equal to the amount of latency your card produces
during the A>D conversion on the input.

Am I making any sense?  Please correct me if I'm wrong, it's still
semi-early and I haven't reached my coffee quota yet.

On Wed, Jan 21, 2009 at 9:42 AM, Mark Knecht <markknecht at gmail.com> wrote:

> I think you're right Brett. I read his email again and decided I got
> fooled by his info about Jack and fell immediately into this old
> multi-card conversation.
>
> Sorry Mark!
>
> - Mark
>
> On Wed, Jan 21, 2009 at 7:30 AM, Brett Clark <brett.clark at zirous.com>
> wrote:
> > I think there's a terminology issue.  Im not sure he's referring to the
> > HW
> > sync during sampling.  I think he's referring to asking about latency
> > compensation
> > when combining a SW like Hydrogen with a real-world recording (like a
> > mic'd amp)
> > to be recorded via Ardour.
> >
> > Ive noticed sometimes when I would be recording and have to "nudge" my
> > track to
> > get it back in time. I just had that happen last week when I was laying
> > a track
> > with WhySynth and noticed the timing was off.  I chalked it up to the
> > fact that
> > im not a keyboard player and did the nudge. ;-)
> >
> > --Brett
> >
> >
> >
> >
> >
> > -----Original Message-----
> > From: ardour-users-bounces at lists.ardour.org
> > [mailto:ardour-users-bounces at lists.ardour.org] On Behalf Of Mark Knecht
> > Sent: Wednesday, January 21, 2009 9:21 AM
> > To: Mark Greenwood
> > Cc: ardour-users at lists.ardour.org
> > Subject: Re: [Ardour-Users] Sync between internal and external sources
> >
> > On Wed, Jan 21, 2009 at 6:50 AM, Mark Greenwood <fatgerman at ntlworld.com>
> > wrote:
> >> I've thought very hard about this question and now my head hurts.. I'm
> >> wondering about how, if at all, Jack/Ardour ensures that all sound
> > sources
> >> stay in sync.
> >>
> >> Let's assume for the moment that I'm capable of playing an instrument
> > such
> >> that I'm in perfect sync with a drumbeat.. (this is a big assumption
> > but we
> >> have to start somewhere.. )
> >>
> >> I'm using Jack. I have Ardour set to JACK Time Master. I have Hydrogen
> > set
> >> up to sync to Jack and play a beat. I have Ardour set up to record me
> >> playing the bass through my soundcard. I press the Play button -
> > Hydrogen
> >> starts playing, I start playing, Ardour starts recording me.
> >>
> >> Question 1 : When I play back my recording of me playing bass, and
> > have
> >> Hydrogen playing along - are they in sync? Or is my bass part now
> > delayed
> >> relative to Hydrogen by a value equal to the latency of my sound card?
> >>
> >> Question 2 : When, at a later date, I mix down by recording the output
> > from
> >> Hydrogen into tracks in Ardour, does the sync change?
> >>
> >> I ask because it sounds like I'm not in sync with my drums but I don't
> > know
> >> if it's me.... It might be that the answer to this is so obvious that
> > I
> >> can't see it for looking. I do know I can't see it... please help..
> >>
> >> Mark
> >
> >
> >
> > Jack itself really doesn't do anything except use a clock from one of
> > the sound cards. We have to ensure that every sound card is using the
> > same clock. By using the right external clock and specifically hooking
> > it up to all sound cards in all systems they all stay in sync.
> >
> > It's possible to use a sound card as the master clock if it has the
> > right outputs. Those outputs *might* be spdif, word clock or ADAT.
> > (Maybe others but those are the ones I've used) you have to enable the
> > output to send the clock and then have to enable the other cards to
> > use that clock instead of its interna crystal.
> >
> > Hope this helps,
> > Mark
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> >
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