[LAU] [Ardour] Offline export with OSC

Aurelien tyranorl at free.fr
Thu May 12 08:59:06 UTC 2011


On Thu, May 12, 2011 at 10:35:08AM +0200, Philipp Überbacher wrote :
> Excerpts from Aurelien's message of 2011-05-12 10:07:48 +0200:
> > On Tue, May 10, 2011 at 11:30:24AM -0400, Paul Davis wrote :
> > > On Tue, May 10, 2011 at 11:14 AM, Joe Hartley <jh at brainiac.com> wrote:
> > > > On Tue, 10 May 2011 10:51:26 -0400
> > > > Paul Davis <paul at linuxaudiosystems.com> wrote:
> > > >> the data path during export is EXACTLY the same as during normal
> > > >> playback except for the conversion to an integer format. since
> > > >> metering occurs before this, the data the metering displays is
> > > >> IDENTICAL to the data that would be seen during normal playback.
> > > >
> > > > It would seem to me that if the meters are checking their inputs
> > > > n times per second, then if an export is occurring and is running say
> > > > 3 times faster than real time, there is the possibility that a peak
> > > > could happen at a moment that the input isn't being checked, and thus
> > > > the peak levels could be reported differently during export than in
> > > > real time.  I wouldn't expect to see a huge difference in the reported
> > > > values, but I can see how this would happen.
> > > >
> > > > Does this make any sense, or have I misunderstood how the meters
> > > > get their values?
> > > 
> > > well, the numerical values should match because the actual "peak"
> > > values are based on all data since the last meter update. but its
> > > definitely true that the "graphical" part of the meters could be
> > > different for precisely the reason you mention on the other hand, if
> > > there *is* a difference, its mostly likely to be an error with
> > > metering and not with any difference in the data generated for export.
> > 
> > OK, not sure to have all understood, but, by the way, when speaking
> > about vu-meters, I obviously mean "numerical values". It's true that I
> > just trusted those values, and never compared them to the data generated
> > for export.
> > 
> > So, just to be sure, I just have to ignore values of meters (including
> > numerical ones?) when exporting, and refering to the ones appearing when
> > listening to my mixes before exporting?
> > 
> > By the way, I would have to retry (and I have no time for this today),
> > but I'm almost sure to have got different numerical values from one
> > "realtime listen" to another. I especially remember a session with a
> > zone in which I sometimes get huge saturation (+1dB or more), and the
> > time right after got -0.8dB. It was a very low dynamic region (metal
> > music), and I had to get it the loudest I could, and it was quite a
> > pain.
> 
> You should try sndfile-info <exported_file>, it's a quick way to get the
> real peak.

OK, thanks.

> Of course it would be nice if ardours metering was correct,
> even on export.

Sure. But, I think at least, it could be useful for "end-users" to know
that they don't have to trust them too much. 

> 
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-- 
Aurélien


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