Audience Text

An FPP plugin that lets a room full of strangers put short messages on one matrix, without letting any of them anywhere near the FPP UI.

Guests join the FPP wifi tether, open one page, type a line, pick a colour or a multi-colour style, and it scrolls across the matrix when their turn comes up. Nothing is shown to two people at once, and nobody can queue-jump by hammering the button.

How the pieces fit

  phone ──POST──> public/submit.php ──> queue.db ──> audiencetextd.py ──> fppd
   (anonymous, port 80 /audience)      (SQLite)      (one message at a time)

Three things are worth knowing before changing any of it.

The audience page is not an FPP plugin page. It is served straight off an Apache Alias from public/, which is outside /opt/fpp/www. That is the whole trick: FPP applies its UI password as a Require directive inside <Directory /opt/fpp/www/>, so anything served through plugin.php inherits the login — correct for the operator's settings page, useless for a page a conference audience has to open. Because public/ lives in a different <Directory> block entirely, toggling the FPP password does not touch it. See scripts/apache-audience.conf.

Only the worker talks to fppd. The web pages never do, not even the operator's Skip button. Every path into the display goes through one process running one message at a time, because that serialisation is the entire product: two overlapping Text effects on one matrix is exactly the failure this plugin exists to prevent. The Skip button marks a row in the database and lets the worker do the talking.

The style catalogue lives in one place. fppd's Text effect takes eleven colour modes and eleven palettes, and most of the 121 combinations are mush on a matrix seen from the back of a room. at_styles() in lib/common.php pairs the ones that work into named styles, and the audience picks a swatch rather than two pieces of jargon. submit.php resolves the chosen id into the four arguments fppd needs and stores them on the row — so the worker replays what it is given and never needs its own copy of that table. Adding a style is a single entry in that one function.

Completion is observed, not guessed. After starting a message the worker polls GET /api/overlays/model/{model} and waits for effectRunning to go false. A scrolling Text effect ends by itself once it has left the screen, so that flag is a real completion signal rather than a timer that hopes for the best. The AudienceTextMaxShowSeconds watchdog only exists for the case where that never happens.

Setup

1. Install the plugin. scripts/fpp_install.sh copies the Apache config into /etc/apache2/conf-available/fpp-audience-text.conf, enables it, and starts the worker.
2. Open Content Setup → Audience Text and choose the model. Until you do, the audience page says the screen is not set up rather than accepting messages it cannot show.
3. The setup page prints the URLs the device is actually reachable on. Once tethering is up, put the tether one on a slide.

Settings that matter on the night

Setting	Why you would touch it
Accept audience submissions	Closes submissions between sessions. The queue stops draining too, so the matrix goes quiet rather than playing out a backlog.
Scroll Direction	Right-to-left, left-to-right, bottom-to-top or top-to-bottom. Long messages suit the horizontal ones: a vertical scroll renders the line at full width, so anything wider than the model is clipped at the sides.
Scroll Speed	The main lever on throughput — it sets how long each message holds the queue.
Offer multi-colour styles	Adds Rainbow, Fire, Party and the rest to the audience's choices. Off leaves only the plain colours.
Logo Image	Shown at the top of the audience page. Upload it first through Content Setup → File Manager → Images, then pick it here. Blank means the page simply starts at the heading — no empty box in front of a room.
Per-Device Cooldown	One submission per IP per N seconds. The only thing stopping one person owning the screen.
Max Queue Depth	Submissions are refused past this, so the wait the page promises stays honest.

What the audience cannot do

• Choose the model, the scroll direction or the speed. All fixed in the settings, which are behind the login.
• Send an arbitrary colour, mode or palette. The browser only ever sends a style id; at_resolve_style() is the allow-list, and anything unrecognised falls back to plain white rather than reaching fppd's colour parser.
• Send anything but printable ASCII, capped at Max Message Length.
• Send a line break. fppd's Text effect reads \n in a message as one, which would put two lines on a display configured to scroll one, so backslash escapes are flattened to spaces at the door.
• Reach anything but index.php, submit.php and status.php. lib/, daemon/, data/ and the operator pages are not aliased and are not reachable from the web at all.

Files

Path	What it is
public/	The only web-reachable, anonymous part
public/logo.php	Serves the one configured logo. A passthrough, not an alias onto the image library, so only that single file is exposed
lib/common.php	Settings, database, sanitising — shared by every PHP entry point
daemon/audiencetextd.py	The worker. Stdlib only, no pip dependencies
api/queue.php	Operator actions, behind the FPP login
scripts/apache-audience.conf	The anonymous-access exemption
data/queue.db	The queue. Created on first use, pruned after 24h

Facts that live in more than one file

The plugin name, the database path, the settings file path and the /audience URL are each spelled out in lib/common.php, daemon/audiencetextd.py and scripts/apache-audience.conf. The queue schema is created by both at_db_migrate() and the worker's migrate(); both are idempotent, and new columns are added by ALTER TABLE in both, because an existing install's CREATE TABLE IF NOT EXISTS will never introduce one. The setting defaults appear in settings.json, lib/common.php and audiencetextd.py — the audience pages and the worker both have to behave correctly before the operator has ever saved the settings page, which on a fresh install means before that file exists. Change one, change them all.

Logs

data/daemon.log, rotated at 1MB with three kept. Every message that goes up (with the style it used), every one that is skipped, and every settings reload is in there.