ReaperForVisual

See where every part of your REAPER mix sits: left or right, low or high, near or far. A 3D stage in your web browser follows the song while it plays, and shows any place in the song when it is stopped.

• Read-only. It never changes your project: not its tracks, its effects, its routing or its undo history.
• On your computer only. A Lua script runs inside REAPER, and REAPER shows the page in your browser. No internet, no account, no AI.
• Free and open source, under the AGPL-3.0.

ReaperForVisual is not made by Cockos. REAPER is a trademark of Cockos Incorporated.

What you need

• REAPER 7 on Windows. It was tested with REAPER 7.82. macOS and Linux have not been tested yet.
• ReaPack, REAPER's free package manager. Step 1 below installs it if you do not have it.
• A web browser.

Install (once, about five minutes)

1. ReaPack. If REAPER's menu bar already has Extensions > ReaPack, skip this step. Otherwise download ReaPack from reapack.com. In REAPER, choose Options > Show REAPER resource path in explorer/finder, put the downloaded file in the UserPlugins folder there, and restart REAPER. The first time, ReaPack shows its list of repositories: click OK.

2. Add ReaperForVisual to ReaPack. Choose Extensions > ReaPack > Import repositories..., paste this link and click OK:

   https://raw.githubusercontent.com/VerkCoding/ReaperForVisual/main/index.xml
   

3. Install it. Choose Extensions > ReaPack > Browse packages..., type ReaperForVisual in the Filter box, right-click ReaperForVisual and choose Install, then click OK. ReaPack lists what it installed: click OK again.

4. Turn on REAPER's web interface. This is what lets REAPER show the page in your browser. Choose Options > Preferences, scroll the list on the left down to Control/OSC/web (near its end), and click Add. Set Control surface mode to Web browser interface, keep the port it offers, leave the other settings as they are, and click OK twice. If you forget this step, ReaperForVisual tells you what to do when you start it, and opens Preferences for you.

5. Start it. Choose Actions > Show action list..., type ReaperForVisual in the Filter box, select Script: ReaperForVisual - Start or stop.lua and click Run. Your browser opens the stage. To stop it, run the same action again.

In the Action List, every ReaperForVisual action is named Script: ReaperForVisual - ... .lua. This page leaves out Script: and .lua.

To start it with one click, put ReaperForVisual - Start or stop on a toolbar (see Keys, menus and toolbars). The button lights while ReaperForVisual runs.

First use

1. The page asks what the stage should show: The whole mix, or The tracks selected in REAPER. Your answer is kept for this project, and you can change it at any time.
2. Press play in REAPER. Each part moves to where you hear it.
3. Stop. The stage now shows the place where the edit cursor is. Click anywhere in the song to see that place.

Play the whole song once. From then on, the stage when stopped is built from what was measured while it played, so it is as accurate as it is while playing.

To look around: drag to turn the view, scroll to zoom, or use the 3D, Top and Front buttons. Hover over a part to read its numbers and the meaning of its marks; click it to keep them shown.

Reading the stage

What you see	What it means
Left or right	Where you hear the part, after every pan, send and bus on its way to the master. The two blue posts are your speakers, and you sit at YOU.
Low or high	The part's spectral centre: deep parts sit near the floor, bright parts high up. The post at the back right shows the scale, from 40 Hz at the floor to 12 kHz at the top.
Near and big, or far and small	How loud the part is compared with the whole mix. The rings on the floor mark 0, -10, -20 and -30 dB.
Wide or narrow	How different the part's left and right are. A mono part is narrow; the less its two sides have in common, the wider it is.
A sphere	A track, a bus (measured at its output), or a group you made for display.
A cloud	A return, such as a reverb or a delay.
A faint shell	A bus or group shown with its tracks inside it.
Hollow	Muted, or silenced by a solo on another track. It stays where it was last heard.

Parts more than 40 dB under the loudest part are hidden, so noise, bleed and dither do not clutter the stage. Change this with Hide under at the top of the page.

A line at the bottom of the page says what the stage is built from at this moment: measured while playing, or worked out from the files where the song has not been played yet.

Marks next to a name

Mark	Meaning
?	The sound does not come from audio files (a virtual instrument or a live input), so the part has no height of its own. 40 % ? means 40 % of a group's level has no height.
≈	A return. Its height comes from what its sends bring it, before its reverb or delay.
anti-phase	Its left and right are out of phase: it is heard wider than the speakers, and it cancels in mono.
est.	A live input (an armed track with monitoring on), estimated through its own pan and fader, without its effects.
approx.	Its way to the master goes through a send taken before the effects, so those effects are not counted.
image gap	Effects on its bus move or widen the image, so the positions of the tracks in that bus are less exact.
muted, silenced	Muted, or cut by a mute above it or a solo elsewhere. Drawn where it was last heard.
measured, model, FX?	Only when stopped, where this part differs from the rest of the stage. measured: as its meter measured it here. model: from its files, with its effects as measured elsewhere in the song. FX?: its effects have not been heard yet, so play this part once.
reading	Its audio files are still being read, and its height may still move. This passes within the first minutes.

Sections

The first list at the top of the page shows a section of the song instead of the edit cursor: the section's average stage, and how much of it was measured while it played.

• Sections are your regions, one section per region, named after it. A region that covers almost the whole song (one made for rendering) is left out.
• A project without regions uses markers whose name starts with #, for example #Chorus 2. Each runs to the next # marker or the end of the project. Other markers, such as notes to yourself, do not split the song.
• The second list chooses where sections come from: regions, # markers, every marker, or none. The choice is kept for the project.

Choosing what is shown

You choose which tracks the stage shows. The whole mix shows every track. With your chosen tracks, a new track appears only when you add it.

• The first card, in a project you have not set up yet: The whole mix, or The tracks selected in REAPER.
• All / chosen, at the top of the page: switch between the whole mix and the tracks you chose. Undo and Redo beside it step back and forward through your view changes while ReaperForVisual runs.
• Tracks, at the top of the page: a list of every track. Tick Show to put a track on the stage. If a track is drawn as the wrong kind, for example a reverb return drawn as an instrument, change its Role there. If a track reaches the master in more than one way, Main path chooses the one it is placed by.
• REAPER actions (in the Action List, type ReaperForVisual):

Action	What it does
ReaperForVisual - Show selected tracks	Shows exactly the tracks selected in REAPER.
ReaperForVisual - Add selected tracks	Adds the selected tracks to the ones shown.
ReaperForVisual - Remove selected tracks	Takes the selected tracks out.
ReaperForVisual - Group selected tracks	Shows the selected tracks as one group, for display only. Your project gets no new folder.
ReaperForVisual - Show all or chosen tracks	Switches between the whole mix and your chosen tracks. Its toolbar button lights while the whole mix is shown.
ReaperForVisual - View menu	All of the above in one menu at the mouse, with Undo and Redo of view changes.

None of them changes your project.

Keys, menus and toolbars

• A key: in the Action List, select the action, click Add... under Shortcuts for selected action, press the key, then click OK. ReaperForVisual - View menu is a good one to give a key: it holds all the others.
• A toolbar button: choose Options > Customize menus/toolbars..., pick a toolbar in the list at the top, right-click where the button should go, choose Insert action..., find the action, click Select/close, then save.
• The track's right-click menu: the same window, with Track control panel context chosen at the top.

What it keeps, and where

• Your choices (what is shown, display groups, corrected roles and main paths, where sections come from) go to a small file next to your project, <project>.rfv.json, when you change them. In a project that has never been saved, they wait until you save it. If that file is ever damaged, it is kept aside under a name ending in .bad, never deleted.
• What playing measured goes to REAPER's resource folder, Data/ReaperForVisual/learned, one file per project. That is how the stage when stopped stays accurate in your next session.
• Nothing else is written. The .rpp file is never touched.

The .rfv.json format is open (see spec/), so other tools can read and write it.

How accurate it is

Each number was measured against renders of every part on its own, on real songs.

• Left or right: within 1 degree nine times out of ten, for each part in each section of the song.
• Level: within about 1 dB per section of the song (the median) on the song it was tuned on, and about 1.5 dB on a second song. A drum trigger, short clicks with silence between them, can show up to 15 dB too loud.
• Height: within about a tenth of an octave (the median) for parts without effects. It is read before the track's effects, so a part with a strong EQ can be two or three octaves off.
• Stopped: where the song has played, as accurate as while playing. Where it has not, about 2 dB, and more for tracks with effects.

Known limits

• Height and width come from each track's audio files, before its effects. An EQ or a stereo widener on a track does not move it, and a return's height comes from what its sends bring it.
• A virtual instrument or a live input has no height of its own (?).
• While recording, an armed track with monitoring on is estimated from its input, without its effects (est.).
• A drum trigger can show too loud (see above).
• A setting changed inside an effect, or an item moved, shows once that part plays again.
• On a large project still being read, a few short parts may show no height for a while.
• Tested on Windows only. Touch screens have not been tried.

Questions

What does the word at the top left mean?

It says	What to do
connecting to REAPER...	Wait a moment: the page is reaching REAPER.
running	Nothing: ReaperForVisual is running.
not started	Run ReaperForVisual - Start or stop in REAPER.
engine stopped	It was stopped. Run ReaperForVisual - Start or stop to start it again.
paused (REAPER busy?)	REAPER is not running scripts at the moment. Close any dialog box in REAPER that waits for an answer: while one is open, scripts wait.
REAPER's web interface is not answering	REAPER is closed, or its web interface is off or on another port. See step 4 of the install.

The browser did not open. Open http://127.0.0.1:8080/rfv/index.html yourself, with the port of your web interface instead of 8080 if it is different. REAPER shows the port in Options > Preferences > Control/OSC/web.

The stage is empty. Check that tracks are chosen (the All / chosen button, or the Tracks list), that the parts are not under the Hide under limit, and that something sounds at the edit cursor.

Nothing moves. Press play. While stopped, the stage stands still at the edit cursor.

I have several projects open. The page follows the project tab that is active in REAPER.

I saved my project under a new name. If ReaperForVisual was running, your choices follow the project. If it was not, the Tracks list offers the choices it finds next to the project: click Use them.

Does it change my project? No. It only reads. See What it keeps, and where.

Does it use the internet? No. REAPER serves the page to your own browser. REAPER's web interface can also be opened from other computers on your network. To limit that, fill in Username:password where you added the web interface.

Is it heavy? No. On a 48-track project it uses about half a millisecond of REAPER's time, ten times a second. On 224 tracks, about 2 milliseconds.

Update and uninstall

• Update: Extensions > ReaPack > Synchronize packages.
• Uninstall: Extensions > ReaPack > Browse packages..., right-click ReaperForVisual, choose Uninstall, then click OK. If you like, also delete the Data/ReaperForVisual folder in REAPER's resource folder and the .rfv.json files next to your projects.

Help and feedback

Found a problem, or have an idea? Open an issue on GitHub. For a problem, say which REAPER version you use, what you did, and what the word at the top left of the page said.

Licence

• ReaperForVisual is licensed under the GNU Affero General Public License v3.0 only. Use it for any audio work, paid or not: the music, mixes and renders you make with it are yours.
• The .rfv.json format in spec/ is under the MIT licence, so other tools can use it.
• The name "ReaperForVisual" and its logo are not licensed under the AGPL. A modified version must use another name.
• Includes three.js (MIT licence).
• For other licensing terms, contact the author.

Copyright (C) 2026 VerkCoding.

Want to help, or build it yourself? See CONTRIBUTING.md.