[linux-audio-user] jamin: lookahead_limiter_const_1906.so ?

[R Parker]

--- Steve Harris <S.W.Harris at ecs.soton.ac.uk> wrote:
> On Sat, May 29, 2004 at 12:35:02 -0700, R Parker
> wrote:
> > > I suspect it should have a peak allowance mode,
> > > which ignores very short
> > > peaks at over 0dB and clips them.
> > 
> > That does seem like an interesting feature. The
> job
> > I'm working on now has transient spikes that are
> > probably +6.0dbfs above the average. I used the
> TAP
> > Scaling Limiter post fader to deal with them. This
> > does a good job.
> > 
> > Do you imagine that spikes of this extreme are
> beyound
> > the scope of the peak allowance mode?
> > 
> > I assume they are. Otherwise, we're probably
> dealing
> > with something that's aggresive enough to become
> > audible if the user isn't able to adjust it. I
> don't
> > really know and am simply speculating.
> 
> I would think 6dB would be in - its a psychoacostic
> effect, humans cant
> detect the harmonic distortion from clipping at very
> short durations (< 1
> ms or so I think).
> 
> In any case it would definatly be an option, the
> extra headroom isn't
> always desirable, and it might be audible under
> certian circumstance

In many ways, I am a simple potato farmin' engineer.
The law says, do no exceed 0.0dbfs. I keep pickin' and
don't exceed that level. Of course our transient
spikes are forcing the desirable content to max at or
below -6.0dbfs--definitely not worth beans.

As an option, do you mean it's part of the user
interface so it can be turned on and off while a
transport is rolling?

With peak allowance mode, we then have a lookahead
peak limiter. Right?

The above example could have been:
*desirable content max -0.2dbfs
*transient peaks +4.0dbfs

This brings me to my next point; I believe our final
output gain should be capable of +6.0 or +10.0dbfs
because the only way I can get close to 0.0dbfs is to;
A. overdrive the limiter with compressor makeup gain,
B. overuse the boost stage, or C. use an external gain
stage (ardour return bus). Of course, A and B produce
distortion. I've done a fair amount of work with JAMin
and the external gain stage is not the exception. It
is the "rule". 

Unfortunately, Ardour return bus settings can only be
recalled using snapshots--imagine a 10 song album.
Snapshots, if at all, can't be effectively recalled
while transport is rolling. So, JAMin Controler and
OSC lose the ability to reference exact levels with a
single button push.

If the JAMin Output has headroom then its capable of
being the final gain stage for every scene/song and
mute or unmute at any Ardour mixerstrip produces final
objective.

Shoot me, I'm guilty of another topic switch/feature
request but make the case based on practicle
experience. With that, I've gotta deal with the
aftermath of having my studio burglarized late last
nite. Oh well, it's part of life and if you asked my
dad he'd tell ya'll I was wrotten kid. :)

ron

> - Steve



	
		
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