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docker-dosbox-novnc/Dockerfile
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jensandClaude Sonnet 5 301503a276 Get game audio into the browser via PulseAudio + a WebSocket bridge
VNC/noVNC only ever streams video, so game sound needed a completely
separate path. Adds pulseaudio/pulseaudio-utils/libasound2-plugins and
routes ALSA's default device through Pulse (/etc/asound.conf), so
dosbox/scummvm need zero special config. server.sh starts one
PulseAudio daemon and one pcm_ws_bridge.py (from docker-common) for the
container's whole lifetime, capturing Pulse's single default sink via
parec.

Audio is a single shared mix, not per-game - considered and dropped a
per-slot-isolated design (mirroring the video architecture) as
unnecessary complexity per direction. Every running game's audio just
mixes into the one default sink; every /screen/<name> page connects to
the same AUDIO_PORT.

setup_server.py gains GET /screen/<name> (an iframe onto the game's
noVNC screen plus an Enable Sound button - browsers require a user
gesture before audio can start) and GET /pcm-worklet.js. The "Open
Screen" link simplifies from a client-side-JS-built cross-port link to
a plain same-origin relative link, since /screen/<name> now reads the
real host server-side from the request's own Host header.

Found and fixed a real bug along the way: parec --device=@DEFAULT_SINK@.monitor
looks correct but fails with "Stream error: Invalid argument" - the
actual PulseAudio macro is the single token @DEFAULT_MONITOR@.

Verified end-to-end with real audio, not just plumbing: confirmed via
`pactl list sink-inputs` that dosbox connects to Pulse correctly
(unmuted, uncorked), then used xdotool to advance stuntcar past its
silent title screen and captured real audible game audio (RMS ~9292)
through the WebSocket bridge with a raw Python client.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NiNnj78HGx1KWyCCo39HSz
2026-07-28 16:27:10 +02:00

42 lines
1.6 KiB
Docker

# syntax=docker/dockerfile:1
FROM ich777/novnc-baseimage
ENV DISPLAY_NUM=99
ENV GAMES_HOME=/opt/games
ENV SCRIPTS_HOME=/opt/scripts
ENV PATH=${PATH}:${SCRIPTS_HOME}
# unzip/smbclient/python3 are needed at runtime: the games are no longer baked into the
# image, setup_server.py serves an HTML install UI (backed by smbget+unzip) that the user
# drives on ${SETUP_PORT} instead of anything being auto-downloaded at container start.
# pulseaudio/pulseaudio-utils/libasound2-plugins carry game audio out to the browser (see
# scripts/pcm_ws_bridge.py) - VNC/noVNC only ever streams video, never audio.
RUN apt-get update && \
apt-get -y install --no-install-recommends dosbox scummvm alsa-utils unzip smbclient python3 \
pulseaudio pulseaudio-utils libasound2-plugins && \
rm -rf /var/lib/apt/lists/*
# Route ALSA's default device through PulseAudio, so dosbox/scummvm need no special config -
# every game's audio ends up mixed into Pulse's one default sink, captured by pcm_ws_bridge.py.
RUN printf 'pcm.!default pulse\nctl.!default pulse\n' > /etc/asound.conf
RUN openssl req -x509 -nodes -newkey rsa:2048 -keyout /tmp/novnc.key -out /tmp/novnc.pem -days 3650 -subj "/C=US/ST=NY/L=NY/O=NY/OU=NY/CN=NY emailAddress=email@example.com"
RUN touch /root/.Xauthority
RUN mkdir -p ${GAMES_HOME}
VOLUME ${GAMES_HOME}
ADD scripts ${SCRIPTS_HOME}
WORKDIR /
EXPOSE 60${DISPLAY_NUM}
EXPOSE 70${DISPLAY_NUM}
EXPOSE 71${DISPLAY_NUM}
EXPOSE 8090-8099
EXPOSE 5900
ENTRYPOINT ["/opt/scripts/server_start.sh", "/opt/scripts/server.sh"]
# see also
# https://github.com/ich777/docker-krusader