meg4/docs/en/tut_snd.md

Sound Effect

In this tutorial we'll prepare and import a sound effect. We'll use Audacity, but other wave editors should work too.

Load Wave

First, let's open the desired wave file in Audacity.

Open the sound wave in Audacity

We can see right away that there are two waves, meaning our sound sample is stereo. MEG-4 can only handle mono, so go to Tracks > Mix > Mix Stereo Down to Mono to convert it. If you see only one waveform, you can skip this step.

Tuning and Volume

Now MEG-4 does tune the samples on its own, and for that to work, all imported waves must be tuned to a specific pitch. For some reason pitch detection is broken in Audacity, so you'll have to do it manually. Press Ctrl+A to select the wave, and then go to Analyze > Plot Spectrum....

Analyzing the spectrum

Move your cursor above the biggest peak, and the current pitch will show up below (which is C3 in this example). If the shown note isn't C4, then select Effect > Pitch and Tempo > Change Pitch....

Changing the pitch

In the "from" field, enter the value that you saw in the spectrum window, and in the "to" field enter C-4, then press "Apply".

Changing the volume

Next thing is to normalize the volume. Go to Effect > Volume and Compression > Amplify.... In the popup window just press "Apply" (everything is autodetected correctly, no need to change anything).

Number of Samples

MEG-4 supports no more than 16376 samples per waves. If you have fewer samples than this in the first place, then you can skip this step.

Under the waveform you'll see the selection in milliseconds, click on that small "s" and change it to "samples".

Changing the unit

In our example that's more than the allowed maximum. The number of samples is calculated as the value under "Project Sample Rate" multiplied by the length. So to lower the number of samples, either we lower the rate or we cut off the end of the wave. In this tutorial we'll do both.

Select everything let's say after 1.0, and press Del to delete. This does the trick, but makes the ending sound harsh. To fix that, select a reasonable portion at the end and go to Effect > Fading > Fade Out. This will make the wave end nicely.

Chopping off and fading out the end

Our wave is still too long (44380 samples), but we can't cut off more without ruining the sample. This is where the sample rate comes in. In previous versions of Audacity, this was comfortably displayed at the bottom on the toolbar as "Project Rate (Hz)". But not any more, on newer Audacity it is a lot more complicated. First, click Audio Setup on the toolbar and select Audio Settings.... In the popup window, look for "Quality" / "Project Sample Rate", and from the drop-down select "Other..." to make the actual input field editable.

WARNING: Make sure you calculate the number correctly. Audacity is incapable of undoing this step, so you can't give it another try!

Enter a number here, which is 16376 divided by the length of your wave (1.01 secs in our example) and press "OK".

Lowering the number of samples

Select the entire wave (press Ctrl+A) then you should see that the end of the selection is below 16376.

Save and Import

Finally, save the new modified wave by selecting File > Export > Export as WAV. Make sure encoding is "Unsigned 8-bit PCM". As filename, enter dspXX.wav, where XX is a hex number between 01 and 1F, the MEG-4 wave slot where you want to load this sample (using a different filename works too, but then the wave will be loaded at the first free slot).

Imported wave form

Once you have the file, just drag'n'drop it into the MEG-4 window and you're done.