[Ardour-Users] zoom of region borders vs waveform displayproblem

[John Emmas]

----- Original Message ----- 
From: "Martin Horn"
>
> also I forgot to say that it only happens after longer recordings of 10
> mins or so and one time also the waveform was drawn out of the borders of
> the region, after bouncing and reinserting everything is fine again with
> the region
>
Several months ago I did some experiments to see if I could fix the current
problems with Ardour's "moving timeline" playback mode.  These are caused by
a recent upgrade to the canvas drawing strategy which causes the CPU to "max
out" in moving timeline mode.  I did fix the problem locally but along the
way I noticed various other issues related to zooming.  Although I did look
closely, I couldn't see anything in my changes that would have introduced
zooming artefacts but because I'd never noticed them before, I hesitated
from releasing anything in case my changes had introduced the problems.  In
my case, the artefacts occurred very sporadically and were impossible to
reproduce reliably.  Nevertheless, they were there and were exactly as you
descibed Martin, namely:-

1)  Waveforms being drawn in the wrong place.
2)  The various time rulers (at the top of the canvas) getting out of sync
with the displayed timeline regions.
3)  Generally occurring after long recordings and/or
4)  With sessions starting at high timecode values or
5)  With lengthy sessions starting close to zero time.

I fixed the problems locally (if "fixed" is the right word) by introducing
some sensible limits on how far in or out the user can zoom - for example
I considered the following scenarios as undesirable:-

1)  Zooming out so much that the entire session takes up only one or two
pixels.
2)  Zooming so much that the timeline would really need to be able to
display negative time to work properly.
3)  Zooming out so much that the playhead (in moving timeline mode) cannot
possibly reach its centre-screen position.

Anyway, the bottom line Martin, is that I have a patch available somewhere
if you or anyone else wants to test it.  The patch is against Ardour2
svn5567 (so quite out of date now) but you can have it if you want.  It goes
without saying that you'd need to be able to build Ardour from source and be
comfortable about applying an (outdated) patch.  I'll be away from home for
the next few days but I could dig it out, sometime midweek.

Regards,

John