Re: kAudioUnitProperty_PresentationLatency supported in LogicPro 7.2 and/or 8?
Re: kAudioUnitProperty_PresentationLatency supported in LogicPro 7.2 and/or 8?
- Subject: Re: kAudioUnitProperty_PresentationLatency supported in LogicPro 7.2 and/or 8?
- From: "I. K." <email@hidden>
- Date: Tue, 13 Nov 2007 19:18:28 -0600
Presentation latency is relevant but its only one part of the timing
information needed to know the host time at the moment the first
sample hits the outs on transport play - If possible at all.
A particular sample will take 'presentation latency' seconds to appear
at the outputs but that doesnt mean, as an example, a call to
CAHostTimeBase::GetCurrentTime() during say, Render was made
'presentation latency' secs before the time the sample is out.
Hosts may issue render notifications in no particular order or timing.
The basic question is, from inside an AU, is it possible to calculate
the HostTime at the moment a sample is going to be out?
ideas are welcome.
Thanks again Bill.
On 11/13/07, William Stewart <email@hidden> wrote:
> In lieu of the property being implemented, I'd suggest that you
> provide a field for the user to set this (and start off with a
> suggested value). This would be good in any case, as there are other
> factors that might contribute to this number (when provided) being a
> reasonable estimate, but not 100% reliable in all cases.
>
> Bill
>
> On Nov 12, 2007, at 6:32 PM, I. K. wrote:
>
> > The project I am working on requires acurate host time stamps of
> > events. These will be made OSC bundles and sent thru udp to control
> > OSC aware applications; SuperCollider3 among them.
> >
> > So far, I have thought of using a digital audio track to send a one
> > sample impulse on transport play. The OSC server application
> > calculates a host time offset from the time it receives this impulse.
> > I dont like that. its hacky.
> >
> > It would be great if the OSC Bundle was built with the correct timing
> > information from the start - in the AU.
> >
> > any sugestions are welcome.
> >
> > Thanks for your help Bill.
> >
> > On 11/12/07, William Stewart <email@hidden> wrote:
> >> This is on our to do list for AULab, but not yet done. I don't know
> >> of
> >> Logic's plans in this area. You are the first to really ask for this,
> >> so perhaps there is enough reason now to look at supporting this
> >> property.
> >>
> >> Bill
> >>
> >> On Nov 12, 2007, at 5:37 PM, I. K. wrote:
> >>
> >>> I searched the archives and found only a couple of references
> >>> regards
> >>> this without much more info than the documentation provided in the
> >>> header.
> >>>
> >>> I have tested on several hosts and none seems to have it implemented
> >>> including AULab.
> >>>
> >>> Perhaps AudioUnitProperties.h misses to mention its only
> >>> applicable to
> >>> output AudioUnits?
> >>>
> >>> As a workaround, is there a way for an AU to get a reference to the
> >>> AUGraph it is connected to?
> >>> This way I could iterate thru the graph collecting latencies and
> >>> calculate a persentation latency for mine - based on buffersize, out
> >>> device safety buffer size, latency etc...
> >>>
> >>> is there any other way?
> >>>
> >>> tia,
> >>> I.
> >>>
> >>>
> >>> On 11/8/07, I. K. <email@hidden> wrote:
> >>>> Hello all,
> >>>> Does anyone know if kAudioUnitProperty_PresentationLatency is
> >>>> supported in Logic Pro 7.2 and/or Logic Pro 8?
> >>>>
> >>>> I would appreciate any hints if this property is not supported.
> >>>> I am coding an AU Instrument so it is only the output presentation
> >>>> latency I am interested in.
> >>>>
> >>>> tia,
> >>>>
> >>>> I.
> >>>>
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>
>
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