VSTI rendering, please confirm

[longimanus]

Hi good KVR peoples.

I'm having small problems with rendering VSTI from Tracktion 2. I posted here: http://forums.mackie.com/scripts/forum/ ... 7;t=000641 (my associate deleted the jpg from the server, but they are not essential anyway) but here it is resumed.

When I render (or export, since it's called render in one window and render on the next) projects that have tracks with VSTI's, every render during a session is slightly different than the previous one, even when no changes have been made.

I first realized that when I made a render, listened to it, then went back to make small adjustment and rendered again. The second render was way different than the small changes I had made.

I tried with various VSTI's with the same result. The Mackie guy that started to get involved with the thread dropped it like a hot potato after a few posts.

Can anybody confirm please?

[Lunch Money]

Can't confirm, but I'll check the Mackie forum... I'd be curious to know which plug-ins, since some of them have humanization/randomization features.

[Lunch Money]

OKeee, had a peek. I strongly suspect WusikStation as the culprit. I own Wusikstation, and a lot of the patches have strange shit going on. Also, only with Wusikstation did I get it responding to the wrong MIDI messages from a controller. I had to filter out anything extraneous with MIDI Ox when I was using my controller (a cheap Yamaha keyboard, but that's beside the point) in conjunction with Wusikstation.

The easiest things to do would be:

a) follow Ben's advice and try a known and stable synth. Heck, even just use the JX10 that comes with Tracktion.
b) upload an edit for someone with WS to peek at. I volunteer myself, but I have only have WS 1.1 installed right now.

Greg

[IIRs]

Its really hard to comment without knowing what sort of differences you are talking about: can you re-upload those pictures, or some sample files, or even just decribe the differences..?

[Lunch Money]

Oh, forgot to mention-- Beno's in the middle of a move right now, so I'm sure he didn't intentionally drop you like a hot potato. Always chaotic when you move.

[longimanus]

I did try with different VSTI. I so far tested with Wusikstation, Pentagon, Augur (freeware), to Beno suggestion Asynth and just tested with JX10 with a very simple midi file, same result.

The thing is, if I render 3 times, I get different result each time but if I close Tracktion and reopen, I get the same 3 result I got before. The VSTI used doesn't seem to make a difference.

If I just render one midi file containing just a few notes, the results is hard to differentiate from one to another by ears, but obvious in an audio editor. A full mix is easy to spot the difference by ears.

I can't upload pictures or sound files now because my associate is in the process of restructuring our website, it's a lot of work and I don't want to mess it up. But it's easy to test for...

Maybe this is normal behavior, but I thought rendering from VSTI was a mathematically precise process and was not expecting difference, certainly not that was audible anyway.

[Lunch Money]

No, you're right. It should produce the same exact results each time. I'd have to know exactly what's going on before I could make an educated guess any further than what I've already made, so I'll wait for screenshots and/or edits.

Something funny's definitely going on, but there's no way to know for sure what it is just yet with the available info.

[longimanus]

Ok, found this image shack thing. Here's the last 3 render from JX10, I circled in red the spot where difference are obvious for clarity.




As I said before, this is just a few notes and the difference is inaudible (to my ears anyway), but it's certainly symptomatic.

And again, it's very easy to test for.

[Lunch Money]

I tested by doing complete renders of the example song, "Tesseract", which to my knowledge doesn't contain any plug-ins that would cause random or 'human' error/behaviour.

Sure enough, there were differences to be found between the two. I couldn't figure out how to cancel phase between them, OR, if I had done it right, they sure didn't produce silence.

Couldn't tell you WHY this is happening, but at least I don't think you're a nutter anymore.

Greg

[sonicfire]

@longimanus: if its inaudible why do you care?

[pHz]

is this a stock wusikstation sample or one of your own youve imported ???

(i cant get wusikstation to replicate this on my system)

sorry to labour the point ... but are you ABSOLUTELY sure theres nothing in the tracktion edit that might be affecting this ???

slainte rob

[longimanus]

@longimanus: if its inaudible why do you care?

A perfect example of why I avoid those forums normally. I think you need to read the thread again, it' inaudible for a few midi notes like this, but a full mix error seems to add up and it become audible, that's how I got to test for the problem in the first place.

Lunch Money, thanks for confirming. I'm glad I'm not a nutter either.

[Lunch Money]

pHz, when I tested, I just used Tesseract, which has all Tracktion-specific plugs. So unless the JX10's LFOs aren't sample-perfect...

Which is possible...

Must. Investigate. Further.

[pHz]

I tested by doing complete renders of the example song, "Tesseract", which to my knowledge doesn't contain any plug-ins that would cause random or 'human' error/behaviour.
Sure enough, there were differences to be found between the two. I couldn't figure out how to cancel phase between them, OR, if I had done it right, they sure didn't produce silence.
Couldn't tell you WHY this is happening, but at least I don't think you're a nutter anymore.
Greg

couldnt see it with a single simple wusik track ... but trying gregs tesseract exercise i CAN see some TINY differences ...

... this is WIERD

slainte rob

[Lunch Money]

What's more, the differences get more pronounced as the timeline moves by. Almost no differences at the beginning, and then by the end it's different..er..tastic!

Sure is WEIRD, eh, teach?