[ardour-dev] Deafening noise from plugins when auditioning/unmuting

[Tom Szilagyi]

On Thu, 25 Aug 2005, Per Sigmond wrote:

> Hi.
> I have this problem in the following curcumstances:
> 
> [...]
> In both cases I get a deafening (loudspeaker breaking) noise that makes me 
> jump high (make sure to turn down the volume before you try this).
> 
> Can anyone duplicate this? If so, what can be done about it?

Hi,

I could reproduce it as you described.

In fact, all that was needed for me was to stop playback while the
plugin was added to a bus (which received input from a regular track,
and outputted to the master bus).

It sounds as if the plugin would receive some strange transient at the
input which caused instability and made it enter a positive-feedback
loop. It's quite strange that this happens, as nothing like this
occurs when the plugin is added to a regular track. I wonder what's
exactly going on here.

I don't know what's different about being added to a bus (from a
plugin's point of view), it would be interesting to write the
signal the plugin receives from ardour to a wav file while the playback
is being stopped, and inspect the results. The plugin may suffer from
instability, but such that normal audio is unable to trigger it.
There must be something that the plugin receives that blows the fuse.

Will try to further investigate it. Any comments welcome.


Tom