ekklesiaandClaude Opus 5
f8ddfbe345
Pressing DVD now enters DVD mode rather than opening VLC. VLC is still the backend, because its dvdnav module is what decodes disc menus and nothing else on Debian does that reliably, but nothing a person can see or press belongs to it any more. classroom-dvd-session owns the whole thing. It puts a full-screen black layer-shell surface up the moment the button is pressed, starts VLC behind it, and drops it once playback is actually on screen — so the harsh cut from wallpaper to VLC's black window is gone, and no partial VLC window or reserved dock strip is ever visible. A deadline drops the surface regardless, because DVD mode must never leave a black screen with nothing behind it. The controls are a classroom bar on the overlay layer, the one layer sway draws above a fullscreen window. It slides up when the pointer reaches the bottom of the screen and hides again shortly after it leaves. It is drawn from the dock's own stylesheet at the room's UI scale, so it is the same surface, the same radius and the same white icons. While hidden it only accepts the pointer in a thin strip along the bottom edge, so a click on a disc menu goes to the disc. The bar reaches VLC through an HTTP interface on loopback behind a password generated per session, sending hotkey *actions* by name. That is what makes the next part possible. All 108 hotkeys VLC 3.0.23 defines are unset, then Space, Esc and the arrow keys plus Enter are bound. Crop, aspect ratio, subtitles, audio tracks and deinterlacing are no longer reachable by pressing a key at random, and the arrow keys no longer change VLC's volume — the television owns volume, and CEC will own it properly later. Esc quits instead of leaving fullscreen. There is nothing to leave, and leaving it was what stranded people on a black VLC window. Close, Eject and Esc all ask VLC to quit and escalate to SIGTERM then SIGKILL if it does not; when VLC exits by any route, including a crash, the session ends and the classroom desktop comes back. Verified against VLC 3.0.23 on Trixie: every argument accepted, every control action accepted over the control interface, a wrong password refused, and quit exiting cleanly. The surfaces were rendered under a headless sway and screenshotted to check the bar against the dock. Co-Authored-By: Claude Opus 5 <[email protected]>
160 lines
5.8 KiB
Markdown
160 lines
5.8 KiB
Markdown
# DVD support
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DVD support is optional per classroom and off by default.
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## Enabling a room
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Edit `/etc/ekklesia-classroom/device.conf` on that endpoint:
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```
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DVD_ENABLED=true
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```
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Then restart the session (reboot, or restart `classroom-dock`).
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With `DVD_ENABLED=false`, or the key absent, the DVD button is not built
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at all and no drive polling happens. Older endpoints get a commented
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`DVD_ENABLED=false` appended on upgrade so the option is discoverable,
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which leaves their behaviour unchanged.
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## Behaviour
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The dock polls the drive every two seconds with the `CDROM_DRIVE_STATUS`
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ioctl. That is a status query, so it does not spin the disc up.
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| State | Dock icon | Clicking the button |
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| --- | --- | --- |
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| No drive connected | DVD logo held back at 55% | "No DVD drive is connected to this classroom computer." |
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| Drive present, no disc | DVD logo held back at 55% | "No disc is in the drive. Insert a disc to get started." |
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| Tray open | held back | "The disc tray is open. Insert a disc to get started." |
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| Disc still being read | held back | "Reading the disc. Please try again in a moment." |
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| Disc ready | DVD logo at full strength | Plays the disc |
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When a disc becomes ready, a **DVD Ready** notification is shown once.
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Discs never play on their own; playback always needs a button press.
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The first poll after login only records what is already in the drive, so
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a disc left in over the week does not announce itself at every boot.
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## Playback: DVD mode
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Pressing DVD does not open a media player. It enters **DVD mode**: a
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full-screen playback surface the classroom owns, with VLC decoding the
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disc behind it.
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`classroom-dvd-session` runs the whole thing:
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```
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black backdrop layer-shell TOP, covers wallpaper and dock while the
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disc loads, hidden once VLC is on screen
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VLC fullscreen, drawn above the top layer by sway
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control bar layer-shell OVERLAY, the one layer sway draws above a
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fullscreen window
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```
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VLC is still the backend because its `dvdnav` module is what decodes
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disc menus, and nothing else on Debian does that reliably. But nothing
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of VLC's own interface is exposed: no menu bar, no panels, no
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fullscreen controller, no cone, and no sway title bar.
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### The control bar
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Move the mouse to the bottom of the screen and a bar slides up. It is
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the same dark translucent rounded surface as the dock, drawn from the
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same stylesheet at the same UI scale, so DVD mode feels like the same
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room. It hides again a second after the pointer leaves it, or after four
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seconds without movement.
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| Control | Does |
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| --- | --- |
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| ⏮ | Previous chapter |
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| ▶ / ⏸ | Play or pause, showing which one it will do |
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| ⏭ | Next chapter |
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| ☰ | Back to the disc menu |
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| ⏏ | Ejects the disc and leaves DVD mode |
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| ✕ | Leaves DVD mode |
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While the bar is hidden it only accepts the pointer in a thin strip
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along the very bottom edge, so a click anywhere else goes to the disc
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menu rather than to an invisible bar.
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The bar reaches VLC over an HTTP control interface on the loopback
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address, behind a password generated for that session alone. Commands
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are sent as VLC hotkey **actions** by name, which is why they keep
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working even though every key has been unbound.
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### The keyboard
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All 108 hotkeys VLC 3.0.23 defines are unset, then these are bound:
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| Key | Does |
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| --- | --- |
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| Space | Play / pause |
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| Esc | Leaves DVD mode |
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| Arrow keys | Move around a disc menu |
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| Enter | Choose the highlighted menu item |
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Nothing else responds. A volunteer cannot land on crop, aspect ratio,
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subtitle tracks, audio tracks or deinterlacing by pressing a key at
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random, and **the arrow keys no longer change VLC's volume** — the
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television owns volume.
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Esc quits rather than leaving fullscreen. DVD mode is the whole screen,
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so there is nothing to leave, and leaving it used to strand people on a
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black VLC window with no way back.
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There is no fullscreen toggle, because DVD mode is not a window.
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### Leaving
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Close, Eject and Esc all do the same thing: ask VLC to quit, and if it
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does not, escalate to SIGTERM and then SIGKILL. When VLC exits — however
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it exits, including a crash — the session ends and the classroom desktop
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and dock come straight back. Nothing can leave a black window behind.
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Only one DVD session can run at a time, however fast the button is
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pressed.
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## Commercial (CSS encrypted) discs
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Most retail DVDs are CSS encrypted, and Debian cannot ship the
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decryption library. Unencrypted discs — curriculum discs, home-burned
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video — play without any extra work.
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**This is automatic.** On any classroom with `DVD_ENABLED=true`, the
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provisioning service installs the codecs after the next boot. See
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[provisioning.md](provisioning.md).
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To do it by hand, or to watch it happen:
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```
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sudo classroom-dvd-css-setup
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classroom-dvd-css-setup --status
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```
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It enables the Debian `contrib` component in whichever APT source format
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the machine uses, installs `libdvd-pkg`, answers its debconf questions
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and builds `libdvdcss`. It only ever adds a missing component to an
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existing Debian entry, so repeated runs cannot produce a duplicate
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repository or a duplicate component, and third-party repositories such
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as Google Chrome's are never touched.
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It needs the network and it compiles a package, which is why it runs
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from the provisioning service rather than the package `postinst`: the
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postinst executes while dpkg is still holding the apt lock.
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## Command line
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```
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classroom-dvd status # drive node, drive state, whether VLC is installed
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classroom-dvd toggle # what the dock button does
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classroom-dvd play # start playback even if the drive is unsure
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classroom-dvd eject # open the tray
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```
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## Permissions
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Reading the drive needs group `cdrom`. The postinst adds the `classroom`
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user to it; that takes effect at the next login, which the OTA reboot
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provides. Without it the drive reads as absent.
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