Author Topic: Instrument Plays the Wrong Notes  (Read 983 times)

Offline I-S3-O

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Instrument Plays the Wrong Notes
« on: February 01, 2018, 08:31:46 »
I have a self-made instrument set here, with a bunch of samples tied to it. I used the sample map to map the samples to the appropriate notes, but when I attempt to use the instrument, all the notes are wrong. Now, the samples are correct: I play them with a real piano, and they sound the same. The instrument is properly mapped to the right sounds (I guess...I mean, it seems like they are), but it's only when I use it is when it's off.

Here's the instrument in question. It's the one called "Ping". The 10th channel exhibits the problem I'm having by playing a simple C major scale...but that is definitely not the C major scale. It's interesting (which is probably why I didn't notice it immediately), but it's not right at all.

Thanks for the assist!

P.S. Don't worry if you don't have the plugins. This is a testing file for the ones I have, and you don't need any for this instrument. Just ignore any warnings that appear about missing plugins.

Offline Saga Musix

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Re: Instrument Plays the Wrong Notes
« Reply #1 on: February 01, 2018, 12:39:07 »
You've just fallen into the trap that I'd call "lack of root note information" in OpenMPT: All your samples are correctly tuned when you play them at middle-C, that's not what you actually do when you trigger a note of the instrument. In the middle column of the instrument's sample map, you see how the sample is transposed. A single row of this table can be read as "When playing a D-5, play a D-5 on sample 16". But since your sample 16 is tuned to D when playing at middle-C, what you play in reality will be an E!
To fix this, there are three ways:
- You either adjust the transposition table so that it reads "When playing a D-5, play a C-5 on sample 16" (i.e. you must edit the middle column of that table for every note).
- You detune the samples so that they all play a C at middle-C. For example sample 16 has to be transposed two notes down (you can use Ctrl+Q/Ctrl+A for quickly transposing samples in the sample editor).
- Prepare your instrument as an SFZ file. OpenMPT will figure out the correct transposition on its own then.

I want to fix this behaviour eventually, but I haven't found the perfect solution that remains compatible to oldskool tracker formats yet.
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Offline I-S3-O

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Re: Instrument Plays the Wrong Notes
« Reply #2 on: February 01, 2018, 18:00:25 »
Aaaaahh, I see.

So then I think the better question is, "Should I even have to do this, though?". The whole reason I was doing it in the first place was because I didn't want any distortion to occur when playing the sample really high. So I thought making one for each note would fix that. I'm not sure if that was right way of doing it, though.

Offline Saga Musix

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Re: Instrument Plays the Wrong Notes
« Reply #3 on: February 01, 2018, 20:27:04 »
Yes, it's the right thing to do - although for this particular example, you  were using way more samples than really necessary, given how simple the instrument sounds. The effective sample rate doesn't change if you do what I described - in the particular example, if you transpose sample 16 two semitones down, it will get transposed up two semitones when you play it, so it's effectively playing at its original sample rate again.
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