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What to do when you can’t line up IRs?

DLC86

Power User
+1, or negative mic values
I think it's better to trim it before importing into the axe, cuz it trims it at the end too and you would end up with an overall shorter IR.

Furthermore the ultrares processing applies a "window" to the IR which progressively reduces the high frequency toward the end of the IR, if you have some silence at the beginning this top end attenuation would start earlier (relative to the impulse) and you'd end up with a darker IR too.
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
Noticed the same thing.. I think the auto-trim algorithm looks for the first non-zero sample to decide where to cut, but sometimes an IR happens to have some non-zero samples before the actual impulse, probably due to noise, and it gets trimmed at the wrong place.

A manual trim function would be useful, manual meaning you can choose the number of samples to trim.
There is no wrong place to trim. It's impossible to know where the data starts because of noise. So we find where the data starts to increase, back up a few samples and trim there.
 

DLC86

Power User
There is no wrong place to trim. It's impossible to know where the data starts because of noise. So we find where the data starts to increase, back up a few samples and trim there.
Yes I know it's not literally "wrong", I just meant that sometimes it happens that it trims way before the impulse starts because of noise, and quite a bit of leading silence remains there
 

shatteredsquare

Power User
Adjacent to auto-trim would be a handy window that lets you manually set how much space you want to trim from the start of a batch of IRs, since they all come from the library author at more or less the same start point.

A window that lets you view the IR waveform on a graph with time markers, and slide a start point marker as close to the waveform start as you like...telling auto-trim to remove that set amount of space from the front of all the IRs in the batch.
 

Perdikament

Power User
Well, thinking about it, it’s not really a big deal that they don’t all trim from the same spot, if you’re using them with another IR type you’re gunna have to line them up anyway, and really, whats it take, 10 seconds to line it up with another similar batched IR??
I personally don’t really see a need to have them all cut perfectly, I was just surprised when I saw it.
 

dumbeat

Inspired
Well, thinking about it, it’s not really a big deal that they don’t all trim from the same spot, if you’re using them with another IR type you’re gunna have to line them up anyway, and really, whats it take, 10 seconds to line it up with another similar batched IR??
I personally don’t really see a need to have them all cut perfectly, I was just surprised when I saw it.
The silence at the start of OHmmer IR's is longer than the available "Mic Distance" time delay in AFIII. So you can't align them if they are not all from the same manufacturer....
 

Jason Scott

Power User
You can also use Axe-Edit to trim the silence.

1. From the Preferences dialog select Cabinet Import and the set the "IR Processing" mode to "Auto Trim".
2. Export the IR from Axe-Manage Cabs.
3. Re-import the Cab to the desired User slot.
I enabled "Auto Trim" and exported one of the Cabs using Cab Manager, then re-imported it, however the lead in silence is still so long that I can't see where the impulse actually starts, unfortunately.
 
It's not an exciting feature, but a manual "trim" for IRs would be useful.
Yes, there are ways to work around it, but they're not an elegant solution (IMO).

I don't fully trust any type of "auto trim" utility.
Tried using those back when I created Purrrfect Drums 1 and 2 (were not consistent/reliable).

I don't love the idea of having multiple copes of the same IRs (some trimmed... other's not).
That's a waste of time/space... and a PITA logistically (to keep all straight/organized).

I'm not a developer, but I can't imagine an IR "start offset" parameter would be that hard to implement... at least not compared to more advanced component/amp modeling parameters.
 

guitarsrule

Inspired
I always thought it would be nice to have an 'auto-align' (align peaks) with IR's along with auto trim, but i'm not sure if auto trim is essentially already 'auto-aligning' them
 
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Perdikament

Power User
I always thought it would be nice to have an 'auto-align' (align peaks) with IR's along with auto trim, but i'm not sure if auto trim is essentially already 'auto-aligning' them
Well maybe if we could zoom in on the wave form for a more accurate alignment of that first peak. Like you can do when aligning tracks in whatever software you use in your DAW.
 
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