by
Sawuare » Mon May 08, 2017 7:15 pm
Hi sunbear,
The key with the yellow rectangle above it is the root key of the sample/instrument plug-in that you are using.
By default, this key is set to A4 (440 Hz).
• For samples:
As each sample has a natural pitch, LMMS needs to know what key should play this pitch. All other notes are generated by changing sample's speed (and so pitch), setting the root key higher will cause a given key to sound lower in pitch and vice versa.
• For instrument plug-ins:
Instrument plug-ins have a natural pitch, too, and it differs between plug-ins (not all plug-ins are developed by the same person and preferences vary).
CONCLUSION: If you have a simple sine wave audio file recorded in the key of A4 (440Hz) and you load it in AudioFileProcessor (the root key is A4 by default) and play the note A4 on your MIDI keyboard, it's going to play it correctly. And if you play the note C5 the sample is going to stretch the key C5 correctly. But if you set the root key to C4 (which is wrong) and play the note A4, you won't get the correct output which is supposed to be A4, because you tuned* your sample to the wrong key.
This matters the most when you have different samples which aren't in the same key, so you should tune* them correctly.
* Tuning is the process of matching the root key of a (sampler / instrument plug-in) with the natural frequency of the (sample loaded in it / the sound it produces).
