Re: [Jack-Devel] Very frustrating problem with JACK and exporting through mixbus

On 05/07/2012 07:40 PM, Jason Jones wrote:

> Okay... A little more info on this little bug.
> 
> I loaded up a new Ardour3 session this morning, recorded one audio track,
> and it exported just fine with Jack2 / Raydat.  I tried exporting 5 times
> in a row, and it worked without issue all 5 times.
> 
> I loaded up a new Ardour2 session, recorded one track, and it exported just
> fine 5 times as well with Jack2 / Raydat.  No problems at all.
> 
> I loaded up a new mixbus session, recorded one track, and it exported just
> fine 5 times as well with Jack2 / Raydat.  No problems at all.
> 
> I then loaded up a finalized session in mixbus with 20 tracks and 10 busses
> (in addition to the 8 default mixbus's), as well as 10-20 plugins running,
> and tried to export - and it failed with the same aforementioned problem.
>  Just hangs, with the "JackFreewheelDriver::Process: Process error" error.
>  In order to exit mixbus, I have to kill through a terminal, too.
> 
> So... Not sure if that sheds light on anything, but for small simple
> sessions, the Jack2 / Raydat combo doesn't seem to have a problem
> exporting.  The only problem I've noticed so far is with big sessions on
> mixbus.

I did and do experience similar issues - problems during export - with
large sessions and automation in A3.

Export either hangs or - if it completes - there are clicks in it.
The source of the problem is invalid automation data. here: only volume
and panning, no plugin/effects are required.

When loading a session that is affected I usually get:
  [WARNING]: Ignoring illegal points on AutomationLine "gain"
messages. Note that ardour3 only shows those messages when loading the
session. The messages do not appear when the automation is created
(here: using a BCF2000).

As workaround I save the session and fix the automation data in .ardour
project file using my favorite text-editor and re-open it.

Previously discussed at
http://old.nabble.com/ardour3-%2B-automation-%2B-fader-desk-td32526713.html

According to Paul there are known issues with the A2/A3 automation
implementation and "we hope that Ben will find some time to port over
the mostly-all-new automation data handling code from mixbus."

Now I'm worried because you experience similar problems in Mixbus.


> I'll try big session on A2 / A3 as soon as I am able.

Can you check the .ardour session-file that fails to export for
automation <events>..</events>. The data between the tags consist of two
numbers per line
  {time in audio-samples} {value}

Here: if the time-value is non-integer (eg. I've seen 14975730.4095213)
or if the value is out of range (negative gain or an exponential number
e.g. 6.22672596364282e-05), export does not work and either hangs or
contains noise.

robin

1336415314.27987_0.ltw:2,a <4FA8144C.5010208 at gareus dot org>