Author Topic: OPL instrument questions  (Read 700 times)

Offline FWL

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OPL instrument questions
« on: December 10, 2021, 14:31:21 »
Hello,

I had three questions regarding the OPL instruments:

1. is it correct that the audio from an opl instrument can't be routed through a vst effect like for example a reverb, in the way that is possible with standard samples? The OPL instrument has to be rendered as a sample if you want to use it in conjunction with vst's?

2. When I set the attack rate of the carrier to maximum (15) nothing happens, it seems that the attack rate is infinitely slow (0)

3. Are the parameters of the OPL instrument 'automatable' via the pattern editor, for example can you change the frequency multiplier of the modulater through pattern commands?

I searched the forum but couldn't easily find a lot of information about the OPL instruments.

Thanks in advance!

Offline Saga Musix

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Re: OPL instrument questions
« Reply #1 on: December 10, 2021, 15:02:26 »
Quote
1. is it correct that the audio from an opl instrument can't be routed through a vst effect like for example a reverb, in the way that is possible with standard samples? The OPL instrument has to be rendered as a sample if you want to use it in conjunction with vst's?
Only global effects can be applied to OPL instruments, yes. Because all instruments share the same virtual OPL chip, it's impossible to route e.g. one OPL instrument to one effect and another OPL instrument to a second affect. This might change in a later OpenMPT version because there are plans to have one virtual OPL chip per instrument, which would allow for greater routing flexibility and more simultaneous voices.

Quote
2. When I set the attack rate of the carrier to maximum (15) nothing happens, it seems that the attack rate is infinitely slow (0)
That's correct. (the values mentioned in that article are mirrored compared to how OpenMPT displays them.) I suppose this was done for symmetry in computation of attack, decay and release, i.e. to simplify the logic of the OPL chip.

Quote
3. Are the parameters of the OPL instrument 'automatable' via the pattern editor, for example can you change the frequency multiplier of the modulater through pattern commands?
The only parameters that can currently be changed are the volumes of the two operators. The volume of the modulator can be changed through Zxx (or any other means of changing the filter cutoff, such as the instrument filter envelope).
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Offline FWL

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Re: OPL instrument questions
« Reply #2 on: December 10, 2021, 15:13:21 »
Thanks for the reply Saga!

And by global effects you mean on the master bus in the general tab, not a vst effect in the plugin slot on the instrument tab

Offline Saga Musix

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Re: OPL instrument questions
« Reply #3 on: December 10, 2021, 15:14:07 »
Yes, any plugin that has the "Master" checkbox checked will apply to OPL instruments.
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