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TOPIC: attenuation modulator destination calculated wrong

attenuation modulator destination calculated wrong 9 months 3 weeks ago #1

  • S. Christian Collins
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In the SoundFont format, there are two primary ways that a sample's volume are controlled:
1. Set the attenuation in an instrument or preset zone.
2. Affect the attenuation via a modulator, such as the default velocity-to-attenuation modulator that allows sample volume to be reduced at lower velocities.

In the first case above (instrument/preset attenuation), the attenuation is actually to be calculated at 40% of the value set. Polyphone does this correctly. This is the only scenario where this 40% rule applies.
In the second case above (modulator destination), the attenuation should be calculated exactly to the value specified (e.g., "960" provides 96 dB of attenuation at velocity 0). However, Polyphone is multiplying this value by 0.4 as well, which is incorrect. This means that all modulators affecting attenuation in Polyphone are only attenuating 40% of what they should be.
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attenuation modulator destination calculated wrong 9 months 2 weeks ago #2

  • Davy
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I am updating the installers and for Ubuntu (if I remember well this is your system) it is ready.

Now attenuations are expressed in real dB in the tables. I don't display both units (real dB and fluidsynth dB) since it is too heavy for the table. There are already a lot of values there. Instead I added an info icon in the header so that users will not be surprised.
I definitely prefer displaying real dB for training our ears against a real unit and for precision in what we write.

I hope the sound engine is now OK for all values. What could be tested for being sure is:
* the attenuation values,
* volume mod LFO (I also fixed a bug here),
* the impact of the low pass filter resonance on the final gain.

Thank you for your interest in Polyphone, your help is really appreciated.

Best regards,
Davy
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attenuation modulator destination calculated wrong 9 months 1 week ago #3

  • S. Christian Collins
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I really like your idea to have the Attenuation field represented in true dB. My last SoundFont project was to convert an SFZ instrument, and I had to run all of the attenuation values through a calculator. This feature will save me a lot of time in the future.

Also, I can verify that velocity-to-attenuation curves are now correct. I'll let you know if I discover anything else that is off regarding attenuation levels. Thanks again! :)
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