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@@ -0,0 +1,83 @@ +LooperTRX +========= + +This tool allows transferring recorded audio data from/to some China-made +looper pedals (see also: https://en.wikipedia.org/wiki/Looper_pedal) over USB. +Unfortunately they are officially only supported by a Windows tool. +To be able to use them with Linux, I analyzed and replicated their USB protocol +in this small script. Though I only tested it with Linux, it should work on all +platforms supported by pyusb (e.g. MacOSX, *BSD). + +I primarily wrote the tool to get support for my "Harley Benton Mini Looper", +but I found that several other brands use the same OEM product; even the +transfer software binaries are almost identical (with minor differences because +of varying company logos). + +The compatible loopers that I found so far are: + + * Harley Benton Mini Looper + * FAME Looper + * Rowin LEF-332 + * Donner Looper + * ammoon AP-09 nano looper + +Note: The Harley Benton looper has the USB ID 0483:572a, so the software is +looking for these devices. Please let me know if other devices are using +different IDs. + + +Usage +----- + +Call it without any parameters to start the graphical interface (if tkinter is available). + +For command line usage: + + $ loopertrx.py rx audio.wav + Receiving..... Done. + + $ loopertrx.py tx audio.wav + Transmitting..... Done. + + +Data format +----------- + +The looper stores files as mono PCM WAV files with 24 bits per sample and a +sample rate of 48000 Hz. +To convert arbitrary audio files to this format, the swiss army knife of sound +processing (sox) can be used: + + $ sox input.mp3 -c1 -r 48000 -b 24 -t wavpcm output.wav + + +External dependencies +--------------------- + + * pyusb (https://walac.github.io/pyusb/) + (On Debian systems: # apt install python3-usb) + * tkinter [optional] (installed by default on most systems) + (On Debian systems: # apt install python3-tk) + + +Linux notes +----------- + +To allow unprivileged users access to the devices, a udev rule can be created. +Create the file /etc/udev/rules.d/99-looperpedal.rules with the following content: + + SUBSYSTEM=="usb", ATTRS{idVendor}=="0483", ATTRS{idProduct}=="572a", GROUP="plugdev", MODE="0660" + +Users in the 'plugdev' group will then be allowed to send/receive data. + + +Current limitations +------------------- + +The official Windows transfer tool does additional audio processing of the +received/sent data (what they store is not the same data that is transferred over USB). +The files are slightly larger in size, perhaps because of some speed adjustments for +local playback. +LooperTRX curently only stores/restores the raw data from the looper devices, without +any modifications. Because of this the audio sounds slightly different when played back +on a computer. |