The feature-set is roughly based on that of the EDP (LoopIII and many features from LoopIV) so reading the EDP Manuals can be useful.

SooperLooper allows you to have any number (limited by available RAM) of loops running simultaneously, and each loop can have an arbitrary number of channels. Each channel of each loop will have an input and output port available for connection under JACK.

Command Options

SooperLooper supports long-presses (from gui, or when commands are bound from MIDI note message). When a command is held down for more than 1 second, it becomes a momentary (or SUS) control, so that when the command is released, it ends the operation (as if you had quickly pressed and released a command twice). In the gui, middle-mouse button press-releases are always momentary (releases always end the operation immediately). MIDI bindings have a SUS option, that if set will treat that binding as an immediate momentary operation (SUS).

Command Reference

Start here. If the record threshold is all the way down, pressing it once will start recording and pressing again will end the recording.

If the Threshold is set higher the loop recording doesn't start until the audio data is greater than the threshold. When finishing the loop, the threshold value is ignored. See the tips in the EDP manual, it works best if you stop and start recording the moment you hit the downbeat, not before. Trust them.

Special Endings
  • If you end a RECORD with another function (OVERDUB, MULTIPLY, REPLACE, SUBSTITUTE, INSERT, ONCE) it will finish the loop immediately (threshold ignored) and start doing the new function.
  • Ending with REVERSE stops recording and plays the loop backwards once then goes into MUTE mode.
This keeps playing the loop and adds whatever you play on top until you stop overdubbing. Very useful.... this is the main tool. The Feedback controls the amount of the original loop that is used every pass. In actuality, when Feedback is set to 100%, it uses a slightly less amount to help prevent clipping on output.
This similar to overdub, except the original loop is repeated underneath you "multiplying" the loop length until you stop it. Thus it can turn a 1 measure loop into a 2,3, etc measure loop. QuantizeMode and RoundMode affect how the overdubbing starts and stops. QuantizeMode affects when the operation begins, and RoundMode affects if the new audio continues to be added throughthe end of the current cycle after hitting the final record.

Keep in mind that the original loop length is a "cycle" and the loop length will be a multiple of that. You can actually make an already multiplied loop have fewer cycles when using Multiply on loops that have already been multiplied.

Special Endings
  • If you end a MULTIPLY with a RECORD press it ends the loop immediately and resets the cycle length to the whole loop.
  • The MultiIncrease function is implemented which allows you to increment the cycle count ahead of time, without needing to wait until the exact time to finish the multiply. Basically, press Multiply as if you were finishing it, then before the current cycle plays out, press Multiply again repeatedly to add cycles. The multiply will resume and automatically go into playback after the specified number of cycles.
It inserts new input in place, but always one "cycle" length... QuantizeMode and RoundMode have effects similar to Multiply.
Special Endings
Ending with a RECORD press it ends the operation immediately and resets the cycle length to the whole loop.
Replaces the audio in the loop for the duration of the command. The existing loop audio is not heard during the operation.

When Quantize mode is set, this operation will be quantized on start and finish with the current sync and quantize parameters.

Is like Replace except you still hear the current underlying loop audio as it records new audio into the loop. On the next time around, only the newly recorded audio will be heard. This helps maintain the groove when recording a replacement section, because you can play with what was there.

When Quantize mode is set, this operation will be quantized on start and finish.

Reverses playback direction. Can be used in play mode, and even during an OVERDUB, which makes for some pretty interesting stuff. Can also be used in DELAY mode. If Quantize is on, the reversal doesn't happen until the next sync boundary, thus keeping the loop in time.
Restores the playing loop to the state before the last operation. It maintains the current time position if the current loop was based on the previous loop (eg, not newly recorded). You can go all the way back to the first one still intact within the loop memory. As more operations are done, more of the available loop memory is used, and it will eventually start reclaiming the oldest versions.

Note that to undo all existing state, do a long-press of Undo.

Pressing Undo when an operation is waiting for sync or quantization will cancel the pending operation.

Redoes the loop if it can (if you haven't done a new operation since your last undo). Taken together UNDO and REDO allow you to do some neat things: record a verse part, then hit record to do a chorus part. To get back to the verse, press UNDO... to get to the chorus press REDO.
Press to mute loop output. Dry passthough audio will be unaffected. To continue playing the loop in time press MUTE again. To continue playing the loop from the top press TRIG. To play back the loop once and return to mute, press ONCE.
this immediately restarts the loop playing back from the beginning.
this immediately restarts the loop playing back from the beginning, and goes into MUTE mode at the end of the loop.
Press to pause loop playback. Dry passthough audio will be unaffected. To continue playing the loop from the paused time press PAUSE again. To continue playing the loop from the top press TRIG. To play back the loop once and return to mute, press ONCE.
Pressing SOLO will mute all other looper instances. Pressing it again will revert to the previous state before solo was pressed (eg, loops that were muted before the first press will stay muted). Pressing solo for a different loop will cause that loop to be the new soloed loop, only one loop may be soloed currently.
These commands allow you to load a loop from an audio file. The file becomes a new loop, so it must be shorter than the available loop time, or the operation will fail. Many audio file formats are supported, but the sample rate should match that of the current loop, as no resampling is currently done on load.

Save will save the current loop to an 32bit float WAV file. The loop playback is not interrupted when saving.

Pressing the Delay control triggers Delay Mode. The time between the most recent two presses is the new delay time. While in DELAY mode, you can toggle Hold Mode (by pressing Replace), or Reverse at any time for a cool effect. To get out of delay mode press any other function or UNDO. You will probably want to adjust Feedback down from 1 before you enter delay mode or you'll build up a nice cacophony fast.
Rate Adjustment
The rate can be adjusted anytime (even during Recording) and will affect both the underlying loop and any new incoming audio recorded onto the loop, reminiscent of tape delay systems. Altering the Rate during recording/overdubbing, etc can result in interesting recorded audio. The GUI has buttons for easy access to 1/2 speed, double speed, and normal (1x) speed. MIDI bindings can be created to act like these buttons by specifying the range min and max to equal the target rate.
By default the Scratch Rate Active is toggled off which means it ignores the Scratch Rate parameter. Changes in the Scratch Position parameter over time define the rate of playback (position unit is ratio of current loop length). The implementation is still pretty rough sounding.

I've personally used a theremin (the PAIA Theremax) with CV output through my MIDI pedal, although the scratching code needs some work.

Control Reference

main in mon
The main in mon control sets the level of any incoming audio for passthrough monitoring to the common outputs.
main out
The main wet control sets master level of all loop audio being sent out the main output ports. It does not affect the passthrough level from the main inputs, use the main in mon control for that.
input gain
The input gain control sets a gain attenuation of the incoming main input audio. This affect the input into the loops only, not the main passthrough monitoring.
The xfade control sets the length in samples that is used to crossfade the audio on loop operations. Useful to prevent unwanted clicks caused by waveform discontinuities. However, if you want them set this value to 0. The control in the GUI affects all loops.
The pan controls sets the panning for a given channel in a loop to the common outputs. Note that the panning does not affect the discrete output ports for each loop, it only pans the signal to the stereo common outputs. A mono loop will have a single panner, and stereo and multichannel loops will have one stereo panner for each channel to allow full control of signal width and panning.
main in
The main in control toggles the use of the main inputs for audio input to the loop. This option only shows up with the loop also has discrete inputs.
Please see the documentation on Sync for a description of other important controls.