The Pi 4's two HDMI connectors share one vc4 DRM card, and DRM master is
exclusive per card -- so the old per-connector-mpv design could never light
the second screen (the mirror mpv died with "Failed to acquire DRM master:
Permission denied"). Replace it with a minimal X server started by the
mediapi-mpv unit via xinit: X is the single DRM master, xrandr --same-as
clones the first output onto every other connected HDMI, and one fullscreen
mpv renders to both. Uses hwdec=v4l2m2m-copy (Pi HW decoder, ~1/3 the CPU of
software) and carries audio + the app's sole IPC socket.
- new scripts/mediapi-session.sh (X client: waits for connectors, mirrors,
execs mpv); rewritten mediapi-mpv unit (xinit on VT7)
- delete scripts/start-mpv.py and all mirror-socket/broadcast code in
player.py, config.py, __init__.py -- a single mpv means one socket
- install.sh installs xserver-xorg-core/xinit/x11-xserver-utils, writes
/etc/X11/Xwrapper.config, adds the user to input,tty
- README + troubleshooting updated
Verified from a cold boot on the Pi: both pixelvalve CRTCs scan the same
framebuffer; app healthy; HW decode engaged.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
