Force Link Audio

Stream your Akai Force's audio over the network as an Ableton Link Audio channel, while the Force stays fully standalone. Pads lit, screen alive, no Computer Mode, nothing flashed.

Any Link Audio receiver picks it up: Ableton Live, an iPad, or another machine on the same network.

A MockbaMod addon. Free and GPL.

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Why

The Force can already send audio over USB, but only in Computer Mode, and that costs you the instrument. I went looking for a way around it and found out exactly why it works that way.

The Force's internal USB hub is a Microchip USB5537B. Computer Mode switches that hub's upstream from the Force's own CPU over to the computer. Your control surface sits on a downstream port of that same hub, so when the computer takes the hub, it takes your pads, knobs and knob screens with it.

That is board topology, not a software lockout. You can confirm it from a shell: flipping USB_MUX_CTRL (GPIO 249, which no kernel driver claims) makes a USB gadget enumerate on the host from standalone. It works. And every control on the Force goes dark except the touchscreen, which survives only because it is I2C rather than USB.

So USB is a dead end for this. The network is not. Hence this addon.

What it does

/usr/bin/MPC ──LD_PRELOAD──▶ forceStream.so ──UDP 127.0.0.1──▶ forceLinkAudio
              (taps snd_pcm_writei)                            (LinkAudioSink)
                                                                     │
                                                  Link Audio on the LAN ▼

forceStream.so interposes ALSA's snd_pcm_writei inside the Force application and copies each audio buffer into a lock-free ring. A background thread sends it to localhost. forceLinkAudio is a separate process that converts to int16 and publishes it as a Link Audio channel.

Keeping the Link stack out of the Force application is deliberate: the tap stays small and real-time safe, and a fault in the network code can never take down the audio engine. The tap passes straight through to the real ALSA function on any error, and drops data rather than ever blocking playback.

The LD_PRELOAD approach is the one MockbaMod already uses for customBufferSize by Amit Talwar. Credit to him for the pattern.

Install

1. Copy the ForceLinkAudio folder to <SD>/AddOns/ on your MockbaMod card.
2. SSH in and run:

   cd /media/662522/AddOns/ForceLinkAudio
   sh install.sh

   (install.sh restores the exec bits that zip strips, and enables autostart.)
3. Reboot.

The Force publishes a Link Audio channel on every boot from then on.

Or grab the zip from Releases.

Settings

AddOns/ForceLinkAudio/config, edited on a computer, then reboot:

PEER="Akai Force"      # name receivers see for this device
CHANNEL="Force Main"   # name of the published channel
PORT=9000              # localhost port only

Enable / disable / remove

sh manage.sh            # status
sh manage.sh DISABLE    # stop, stay installed
sh manage.sh ENABLE     # turn back on
sh manage.sh UNINSTALL  # remove

Nothing is written outside the SD card and /dev/shm. Pull the card, or disable, and the Force is stock again.

Known limits

• Stereo main mix only. The Force presents a 4-channel device to ALSA but channels 3/4 are silent, so there are no per-track stems available this way.
• Latency is almost entirely the receiver's. This addon's own contribution is about 20 ms, measured — a few milliseconds of ring plus one commit block. What you actually feel is your receiver's jitter buffer. Link Audio receivers buffer to stay beat-aligned, and if a receiver expresses that buffer as a number of beats rather than milliseconds, its latency will scale with your session tempo: the same receiver can be under two seconds at 130 BPM and over three at 75. If the delay feels wrong, check the receiver before suspecting the network.
• The daemon listens on 127.0.0.1 only. The tap never sends anywhere else, so there is nothing to reach from another machine — deliberately, since a wildcard bind would let anyone on the same network publish audio as your instrument.
• Clock drift is tolerated, not corrected. The Force's 44.1 kHz crystal is not your receiver's clock — measured here at about 116 ppm apart, or roughly a beat every few hours. Rather than resample or splice samples continuously to hide that, the bridge lets it accumulate and resynchronises once when it passes two beats. On a normal session you will never reach it. Correcting it properly needs a real resampler, which is not worth the artifacts it would trade for.
• Tested on MockbaMod, Force firmware 3.x, kernel 6.6.95, armv7l. Only tested on one machine so far — reports welcome.

Build

Needs zig as a cross-compiler and an Ableton Link checkout that includes Link Audio.

cd src
LINK=/path/to/link ./build.sh

src/receive.py is a plain UDP receiver that writes a WAV, useful for testing the tap with Link out of the picture.

License

GPLv2-or-later. This links Ableton Link, which is dual-licensed GPLv2+ / commercial; this addon ships under the open-source branch. Ableton Link is © Ableton AG.

Not affiliated with or endorsed by Akai Professional, inMusic, or Ableton AG. Use at your own risk.