Designed, coded, and hand-built in France

Capture and Power Link Modules included + A free AV-to-USB converter is included for modular systems without HDMI output. Ready to use

Razmasynth / Mapler v2026.04:

Design your content, place your surfaces, apply a global warp, and perform the final composition in real time using joystick, buttons, and external TRIG input.

With QUAD and COMPLEX mesh surfaces, USB preset saving, factory presets, TRIG sequencing, Master Output warp, Play Mode, inertia, and Hold, Mapler turns video mapping into a hands-on musical performance tool.
Standalone real-time video mapping instrument for Eurorack performance.

1. Overview

Mapler is a standalone video mapping instrument designed to be played like a musical device.

Control your visuals using the built-in joystick for fast, expressive gestures, or a USB mouse for precise editing.

It processes external video sources, including live video input from USB capture devices, cameras, video mixers, and other HDMI-to-USB sources.

Built around a unique 4-layer workflow — Atelier, Output, Master, Play — Mapler gives direct hands-on control over your visuals, from composition and mapping to global warping and live performance.

Mapler is also the perfect companion to the Video Slooper, expanding a video setup into real-time mapping, sequencing, and performance.

2. The 4-Layer Workflow

Atelier — Design your content

Atelier is where you select and sculpt the part of the incoming video signal used by each shape.

In Atelier, you can:

• define the source area of a shape;
• move, scale, and rotate the selected video region;
• edit QUAD or COMPLEX mesh source geometry;
• create visual compositions from the incoming video feed.

Atelier is the content-design layer.

Output — Place your surfaces

Output is where shapes are positioned in the final output space.

In Output, you can:

• place each surface on screen;
• move, rotate, and scale surfaces;
• edit corners and mesh borders;
• snap vertices together for precise alignment;
• use local Quad Warp anchors on COMPLEX meshes.

Output is the mapping-placement layer.

Master — Apply global warp

Master Output applies a final global deformation to the whole mapped composition.

This is useful for adapting the final image to:

• projection surfaces;
• screens that are not perfectly aligned;
• walls, objects, installations, or stage setups;
• a final trapezoid correction after all shapes are already mapped.

The Master warp is independent from individual surfaces and is saved inside presets.

Play — Perform your visuals

Play Mode turns the whole mapped composition into a live instrument.

In Play Mode, the joystick no longer moves the editing cursor. Instead, it performs the final composition in real time with:

• Z rotation;
• X/Y tilt;
• global scale;
• inertia;
• Hold mode.

Play transformations are temporary performance gestures and do not edit the underlying mapping.

3. Video Input

Mapler uses USB video input.

Typical compatible sources include:

• USB HDMI capture dongles;
• video mixers;
• cameras;
• HDMI output from other video instruments;
• computers or media players via HDMI capture.

If the video signal is lost for a few seconds, Mapler automatically restarts to recover the input.

4. Surfaces and Shapes

Mapler can handle up to 128 surfaces.

Each surface can be either:

• QUAD — a simple 4-corner mapped surface;
• COMPLEX — a 16×9 editable mesh with source and output deformation.

QUAD surfaces

A QUAD is the simplest mapping shape. It has four corners and can be moved, scaled, rotated, and warped.

COMPLEX surfaces

A COMPLEX surface uses a 16×9 mesh. This allows organic border deformation while automatically recomputing the interior mesh.

COMPLEX mode is designed for more sculptural mapping, irregular surfaces, masks, circles, curved forms, and organic visual deformation.

Once a surface has a custom COMPLEX mesh, it does not return to QUAD mode. This protects detailed mesh edits from being accidentally destroyed.

Built-in shape cycle

The COMPLEX button cycles the selected surface through:

1. QUAD → COMPLEX standard mesh
2. COMPLEX standard → perfect square
3. perfect square → perfect circle
4. perfect circle → COMPLEX standard

The new shape is recentered on the previous shape center.

5. Cursor and Editing

Mapler can be controlled using the built-in joystick or a USB mouse.

Mouse movement temporarily takes priority over joystick movement, allowing fluid switching between both control methods.

In Output mode, Mapler uses Clean Output Mode: after about 2 seconds without cursor activity, the cursor and selected-surface overlay are hidden for a clean stage output.

In Atelier mode, cursor and overlays remain visible.

6. Basic Editing Operations

Select a surface

Move the cursor near the center of a surface and press the joystick click / left mouse button.

If several surfaces are close, Mapler selects the closest center.

Move a surface

Hold joystick click / left mouse button on the center of a surface and move the joystick or mouse.

In Atelier, this moves the source region.
In Output, this moves the mapped surface.

Move a vertex

Click and drag a corner or mesh border vertex.

In Atelier, vertex movement edits the source region.
In Output, vertex movement edits the mapped output shape.

Deselect

Click in empty space to clear surface selection.

7. Rotate and Scale

Rotate

Hold ROTATE and move the joystick.

A short tap / click without significant movement applies a rotation step of approximately 5°.

A drag applies smooth rotation at approximately 0.3° per pixel.

Rotation works in both Atelier and Output:

• in Atelier, it rotates the source selection;
• in Output, it rotates the mapped surface.

For COMPLEX surfaces, rotation affects the full mesh.

Scale

Hold SCALE and move the joystick.

A short tap / click without significant movement applies a scale step of approximately ×1.05.

A drag applies smooth scaling at approximately 0.003 per pixel.

Scaling works in both Atelier and Output:

• in Atelier, it scales the source selection;
• in Output, it scales the mapped surface.

For COMPLEX surfaces, scaling affects the full mesh.

8. COMPLEX Mesh Editing

COMPLEX surfaces use a 16×9 mesh.

Only the border vertices are directly selected. When a border vertex is moved, Mapler spreads the deformation along the related border and recomputes the interior mesh automatically.

This creates an organic, ZBrush-like 2D editing feel.

Border deformation

Dragging a mesh border vertex affects nearby vertices with a falloff. Corners receive reduced influence when editing a non-corner border point.

Interior recomputation

After border editing, the mesh interior is recomputed automatically using a smooth surface interpolation. This keeps the mesh coherent and avoids hard broken geometry.

Vertex snap in Output

In Output mode, vertices can snap to other surface vertices.

Snap uses two thresholds:

• snap-in: approximately 10 px;
• snap-out: approximately 18 px.

When snap is active, the active vertex and target are highlighted.

9. Local Quad Warp Anchors

In Output mode, a selected COMPLEX mesh shows four orange anchors around its bounding box.

Dragging one of these anchors applies a temporary quad-style deformation to the whole mesh. This is useful for quickly turning a detailed mesh into a trapezoid or adapting a complex shape to a physical surface without editing every border point manually.

This feature is best described as:

Local Quad Warp for COMPLEX meshes

or:

Mesh Quad Warp Anchors

10. Master Output

Master Output is a global warp layer applied after all surfaces have been rendered.

It works as a final quad deformation over the complete output composition.

Enter Master Output edit mode

Press MASTER OUTPUT while in Output mode.

Master Output edit mode is ignored in Atelier mode.

Edit Master Output

In Master edit mode:

• drag a corner to warp the global output;
• drag the center to move the whole Master quad;
• release near the screen corners to snap close values back to exact full-screen corners.

Master LED feedback

• OFF: Master Output is neutral.
• ON: Master edit mode is active.
• Slow blink: Master Output is modified but not currently being edited.
• Fast blink: Play Hold is active.

11. Play Mode

Press PLAY to enter or leave Play Mode.

When Play Mode is active, the joystick no longer moves the editing cursor. It controls the final mapped composition as a performance layer.

Play controls

Without joystick click held:

• joystick X controls Z rotation;
• joystick Y controls global scale.

With joystick click held:

• joystick X/Y controls 3D-style X/Y tilt;
• Z rotation remains available.

Inertia

In Play Mode, press CLIP to toggle inertia.

When inertia is enabled, movement accumulates velocity and slowly decays with a friction value around 0.995. This allows long spinning and fluid kaleidoscopic motion.

Hold

In Play Mode, press SCALE to toggle Hold.

Hold stores and replays the last strong joystick movement:

• Z Hold for normal rotation;
• X/Y Hold when joystick click is held.

Press SCALE again to disable Hold and clear held values.

When Hold is active, the Master LED blinks quickly.

Play reset

Leaving Play Mode resets the temporary Play transform: rotation, tilt, scale, velocities, and held values are reset.

The underlying mapping and presets are not changed.

12. Save, Load, USB Slots, and Factory Presets

Mapler uses a .mapler preset format that stores:

• all surfaces;
• selected surface state;
• preview/output state;
• QUAD geometry;
• COMPLEX mesh source and output geometry;
• Master Output warp.

Startup auto-load

On boot, Mapler tries to load:

1. USB MAPLER_SAVES/LAST_SAVED.mapler
2. RAM working preset /tmp/mapler_working.mapler
3. default internal startup surface if no saved file exists

Quick Save

Press SAVE.

Mapler saves:

• current session to /tmp/mapler_working.mapler;
• USB backup to MAPLER_SAVES/LAST_SAVED.mapler if a USB drive is present.

The Output LED blinks to confirm.

Quick Load

Short press LOAD.

Mapler loads:

1. USB LAST_SAVED.mapler if available;
2. RAM working preset if no USB save is found.

The Output LED blinks to confirm.

USB slots

Mapler supports USB slot saves:

• SLOT_01.mapler
• SLOT_02.mapler
• …
• SLOT_99.mapler

Slots are stored in:

MAPLER_SAVES/

Save to slot

Hold SAVE and press:

• NEXT: save to first free slot;
• PREV: save to last existing slot, or slot 01 if none exists.

Load from slot

Long press LOAD for about 350 ms to arm USB browse mode, then while holding LOAD:

• press NEXT to load the next existing USB slot;
• press PREV to load the previous existing USB slot.

Factory presets

Factory presets are stored on the boot partition:

/boot/firmware/MAPLER_PRESETS/

with names:

• PRESET_01.mapler
• PRESET_02.mapler
• …
• PRESET_99.mapler

Long press COMPLEX for about 700 ms to arm factory preset browse mode, then while holding COMPLEX:

• press NEXT to load the next factory preset;
• press PREV to load the previous factory preset.

13. TRIG Input and Sequencer Modes

Mapler can step through USB slot presets using the TRIG input.

TRIG loads presets from MAPLER_SAVES/SLOT_01.mapler to SLOT_99.mapler.

The TRIG input has an anti-double-trigger refractory time of approximately 120 ms.

TRIG MODE button

Press TRIG MODE to cycle through:

1. OFF
2. NORMAL
3. PINGPONG
4. RANDOM
5. back to OFF

TRIG modes

OFF

TRIG input does nothing.

NORMAL

Each TRIG loads the next existing USB slot. When the end is reached, it wraps around.

PINGPONG

Each TRIG moves forward through existing slots. At the end, direction reverses and slots are loaded backwards.

RANDOM

Each TRIG loads a random existing slot.

TRIG LED feedback

• OFF: TRIG mode OFF.
• ON: NORMAL mode.
• Slow blink: PINGPONG mode.
• Fast blink: RANDOM mode.

14. Button Reference

POWER
The POWER button is a hardware power control connected directly to the Raspberry Pi. It is independent from the Mapler software and can be used to start the unit or request a clean shutdown, depending on the Raspberry Pi power state.

OUTPUT

Toggle between Atelier and Output modes.

Also exits Play Mode and Master edit mode when returning to Atelier.

NEXT / PREV

Normal mode:

• NEXT selects the next surface;
• PREV selects the previous surface.

With SAVE held:

• SAVE + NEXT saves to first free USB slot;
• SAVE + PREV saves to last existing USB slot, or slot 01 if no slot exists.

With LOAD long-held:

• LOAD + NEXT loads next USB slot;
• LOAD + PREV loads previous USB slot.

With COMPLEX long-held:

• COMPLEX + NEXT loads next factory preset;
• COMPLEX + PREV loads previous factory preset.

NEXT + PREV

Hold both for about 3 seconds to reboot the system.

ADD SHAPE

Short press:

• add a new QUAD surface.

Long press, about 2 seconds:

• delete selected surface.

COMPLEX

Short press:

• cycle selected surface shape: QUAD / COMPLEX / perfect square / perfect circle.

Long press, about 700 ms:

• arm factory preset browsing with NEXT / PREV.

ROTATE

Hold:

• rotate selected surface using joystick movement.

Short tap / release without movement:

• rotate by about 5°.

SCALE

Outside Play Mode:

• hold and move joystick to scale selected surface;
• short tap / release without movement applies a small scale step.

Inside Play Mode:

• toggles Hold mode.

JOY CLICK

Outside Play Mode:

• acts as left mouse click;
• select, drag, move vertices, edit mesh, or drag Master Output.

Inside Play Mode:

• changes joystick behavior from Z rotation / scale to X/Y tilt control.

CLIP

Outside Play Mode:

• short press: copy selected surface;
• long press, about 700 ms: paste copied surface at cursor position.

Inside Play Mode:

• toggles inertia.

SAVE

Short press:

• quick save to RAM and USB LAST_SAVED if available.

Hold + NEXT / PREV:

• save to USB slots.

LOAD

Short press:

• quick load from USB LAST_SAVED, then RAM working preset if needed.

Long press, about 350 ms:

• arm USB slot browse with NEXT / PREV.

MASTER OUTPUT

In Output mode:

• toggle Master Output edit mode.

In Atelier mode:

• ignored and forced off.

PLAY

Toggle Play Mode.

Entering Play Mode clears active editing states and hides the cursor.

Leaving Play Mode resets temporary Play transforms.

TRIG MODE

Cycle TRIG workflow mode:

• OFF;
• NORMAL;
• PINGPONG;
• RANDOM.

TRIG

External trigger input.

When TRIG mode is active, loads USB slots according to the selected TRIG mode.

15. LED Reference

Output LED

• OFF: Atelier / Preview mode.
• ON: Output mode.
• Blinks 3 times: save/load action feedback.

TRIG Mode LED

• OFF: TRIG mode off.
• ON: NORMAL mode.
• Slow blink: PINGPONG mode.
• Fast blink: RANDOM mode.

Master LED

• OFF: Master neutral / no active Master status.
• ON: Master edit mode active.
• Slow blink: Master Output modified.
• Fast blink: Play Hold active.

16. Performance Notes

• Mapler is designed for live use and clean stage output.
• Output overlays auto-hide after inactivity.
• Play Mode gestures are temporary and non-destructive.
• Master Output is saved in presets.
• COMPLEX meshes are protected from accidental return to QUAD.
• Watchdog relaunch is expected behavior after signal loss or new device detection.

18. Optional Companion Modules

Optional companion modules:

-Capture - USB video input (2HP)

– CRT Expander — converts HDMI output (Mapler / Slooper) to composite video (4HP)

– Power Link — 5A power solution (4HP)

– Display — a dedicated HDMI video monitor (18HP)