Many of the example programs in Allolib Playground have a feature where you can record sequences.

For example, when you do run.sh tutorials/synthesis/01_SineEnv_Piano.cpp you get this control panel:

The part we want to focus on is the part near the bottom:

This provides a sequencer feature where you can press Record and record a sequence of notes that you play on the keyboard. You can then play back these sequences.

The sequences are stored in a file with the name you give it, and the extension .synthsequence. They are stored in a bin subdirectory in the same directory where the source code is found. Under that directory, you’ll find a subdirectory with the same name as the instrument (e.g. SineEnv) followed by the suffix -data.

So, for example, for any file under tutorials/synthesis that use the instrument name SineEnv, the directory will be tutorials/synthesis/bin/SineEnv-Data and the files will be piece1.synthsequence, piece2.synthsequence etc.

Inside this file, you’ll find data such as this:

@  0   3.5 SineEnv 0.3 260   .011 .2 0.0
@  0   3.5 SineEnv 0.3 510   .011 .2 0.0
@  3.5 3.5 SineEnv 0.3 233   .011 .2 0.0
@  3.5 3.5 SineEnv 0.3 340   .011 .2 0.0
@  3.5 7.5 SineEnv 0.3 710 1, 2 0.0
# etc.

• The @ means a command (to play a note).
• The # means a comment.
• For lines with @, the first four columns are always fixed:
  • Column 1 is @
  • Column 2 is the start time for the note
  • Column 3 is the duration of the note
  • Column 4 is the instrument name
• The remaining columns are the parameters of the specific instrument

For example, for the SineEnv instrument, the columns are:

• amplitude
• frequency
• attackTime
• releaseTime
• pan

You can see this in the C++ source code here, inside the init function for the SineEnv instrument:

    createInternalTriggerParameter("amplitude", 0.3, 0.0, 1.0);
    createInternalTriggerParameter("frequency", 60, 20, 5000);
    createInternalTriggerParameter("attackTime", 1.0, 0.01, 3.0);
    createInternalTriggerParameter("releaseTime", 3.0, 0.1, 10.0);
    createInternalTriggerParameter("pan", 0.0, -1.0, 1.0);

You typically see a comment in the file to remind you of what these parameters mean:

# SineEnv amplitude frequency attackTime releaseTime pan 

Other symbols

Other symbols have meanings: >, ::, =, +, t (documentation is missing for these)