[LAU] [Ardour] Offline export with OSC

[Philipp Überbacher]

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