Files
Classroom_Desktop/docs/dvd.md
T
ekklesiaandClaude Opus 5 c81fc1b0b9 feat: dress VLC down to an appliance screen
Stock VLC looks like a desktop media player, which is wrong for a room
where the TV is the whole interface. VLC stays the backend because its
dvdnav module is what provides the disc menus, and menus are the part
that matters on a commercial disc.

It is dressed down with documented VLC 3.x options, all verified against
the 3.0.23 build in Debian Trixie: minimal view, dark palette, no cone,
no tray, no now-playing popups, no resume prompt, no recent-disc
history, no title banner. sway draws no border on the window either, so
there is nothing above the video.

The auto-hiding fullscreen controller is deliberately kept: it is not
persistent chrome, and it is the only way a volunteer with a mouse can
pause or change chapter.

No skin is involved. Skins replace the interface wholesale and take the
keyboard and mouse handling that DVD menu navigation depends on with
them, as would --intf dummy.

Also drops --no-qt-updates-notif, which was not an option in Debian's
VLC at all. It made VLC exit before it started, so the DVD button could
never have launched a disc.

Co-Authored-By: Claude Opus 5 <[email protected]>
2026-09-04 21:33:22 -05:00

5.1 KiB

DVD support

DVD support is optional per classroom and off by default.

Enabling a room

Edit /etc/ekklesia-classroom/device.conf on that endpoint:

DVD_ENABLED=true

Then restart the session (reboot, or restart classroom-dock).

With DVD_ENABLED=false, or the key absent, the DVD button is not built at all and no drive polling happens. Older endpoints get a commented DVD_ENABLED=false appended on upgrade so the option is discoverable, which leaves their behaviour unchanged.

Behaviour

The dock polls the drive every two seconds with the CDROM_DRIVE_STATUS ioctl. That is a status query, so it does not spin the disc up.

State Dock icon Clicking the button
No drive connected DVD logo held back at 55% "No DVD drive is connected to this classroom computer."
Drive present, no disc DVD logo held back at 55% "No disc is in the drive. Insert a disc to get started."
Tray open held back "The disc tray is open. Insert a disc to get started."
Disc still being read held back "Reading the disc. Please try again in a moment."
Disc ready DVD logo at full strength Plays the disc

When a disc becomes ready, a DVD Ready notification is shown once. Discs never play on their own; playback always needs a button press.

The first poll after login only records what is already in the drive, so a disc left in over the week does not announce itself at every boot.

Playback

Playback is VLC, chosen over mpv because mpv dropped DVD menu support. VLC's dvdnav module is what provides the disc menus, and dvd:// selects it.

classroom-dvd toggle hands the disc to VLC through classroom-window, so the DVD player behaves like any other classroom application: the DVD button focuses it, minimises it, and restores it. Super+M minimises it too. VLC starts fullscreen; Esc leaves fullscreen.

How VLC is made to fit the classroom

Stock VLC looks like a desktop media player, which is wrong for a room where the TV is the whole interface. It is dressed down with documented VLC 3.x options — no skin is involved, because skins replace the interface wholesale and take DVD menu input with them:

Option Why
--fullscreen The disc opens straight onto the TV
--qt-minimal-view No menu bar or extended panels
--qt-dark-palette Dark window instead of the default light grey
--no-qt-bgcone No orange cone, no album-art panel
--no-qt-system-tray Not a background desktop application
--no-qt-name-in-title Nothing in the title bar to read
--no-qt-video-autoresize The window does not jump to the video size
--qt-notification=0 No now-playing popups
--qt-continue=0 Never asks to resume where it left off
--no-qt-recentplay No history of the discs a classroom has played
--no-qt-privacy-ask No first-run privacy dialog
--no-video-title-show No title banner over the video

sway also draws no border on the VLC window (for_window [class="(?i)vlc"] border none), so there is no title bar above the video either.

The auto-hiding fullscreen controller is deliberately kept. It is the only way to pause or change chapter with a mouse, it is not persistent chrome, and a volunteer with a wireless mouse needs it.

--intf dummy would give an even barer window, but the dummy interface takes the keyboard and mouse handling that DVD menu navigation depends on, so it is not an option here.

Note that --no-qt-updates-notif, which earlier classroom builds passed, is not an option in Debian's VLC at all — it made VLC exit before it started.

Commercial (CSS encrypted) discs

Most retail DVDs are CSS encrypted, and Debian cannot ship the decryption library. Unencrypted discs — curriculum discs, home-burned video — play without any extra work.

This is automatic. On any classroom with DVD_ENABLED=true, the provisioning service installs the codecs after the next boot. See provisioning.md.

To do it by hand, or to watch it happen:

sudo classroom-dvd-css-setup
classroom-dvd-css-setup --status

It enables the Debian contrib component in whichever APT source format the machine uses, installs libdvd-pkg, answers its debconf questions and builds libdvdcss. It only ever adds a missing component to an existing Debian entry, so repeated runs cannot produce a duplicate repository or a duplicate component, and third-party repositories such as Google Chrome's are never touched.

It needs the network and it compiles a package, which is why it runs from the provisioning service rather than the package postinst: the postinst executes while dpkg is still holding the apt lock.

Command line

classroom-dvd status    # drive node, drive state, whether VLC is installed
classroom-dvd toggle    # what the dock button does
classroom-dvd play      # start playback even if the drive is unsure
classroom-dvd eject     # open the tray

Permissions

Reading the drive needs group cdrom. The postinst adds the classroom user to it; that takes effect at the next login, which the OTA reboot provides. Without it the drive reads as absent.