Pixelbook Go + Arch Linux — Complete Camera Guide

Everything needed to make the Google Pixelbook Go (Atlas, 2019) camera work on a fresh Arch Linux install: the built-in IMX208 sensor, correct colors, and a virtual camera that WeChat and Tencent Meeting (wemeet) accept.

The work is split into three independent layers. Each has its own folder with details and its own README:

Layer	Folder	What it fixes
1. Sensor enablement	imx208-ipu3-camera-fix/	Camera does not exist at all
2. Image quality	imx208-camera-color-fix/	Picture almost black / wrong colors
3. Virtual camera	(this repo, root)	WeChat / wemeet can't use the IPU3 camera

Plus the hard-won app-compatibility knowledge in §6.

Problems this guide solves

Everything below was hit on real hardware and is fixed here. If you only want the story of why things were broken, read this table top to bottom.

Symptom	Root cause	Fix
No camera device at all	libcamera has no IMX208 sensor-helper/properties, refuses to init	patched libcamera (§1)
Picture nearly black, wrong colors	IPU3 IPA falls back to empty uncalibrated.yaml; AGC never touches digital_gain	imx208.yaml tuning + digital-gain script (§2)
Picture pulses/flickers indoors	exposure time not a multiple of the 50 Hz mains cycle (100 Hz light ripple)	tuning curve pins exposure at 10 ms (§2)
Flicker returns in dim rooms	pinned window is only 8× wide; dark scenes push AGC off the 10 ms pin	imx208-auto-dgain.sh watcher adapts digital gain (§2)
WeChat / wemeet can't use the camera	they only understand UVC-style /dev/video*, not IPU3/libcamera	v4l2loopback virtual camera + feed (§3)
Only one app can open the camera; second gets EBUSY	v4l2loopback token model: single capture owner; apps also probe on one fd and capture on another	shared-capture driver patch (§3.1)
wemeet camera black, other apps fine	TRTC sends DQBUF/QBUF with memory=0; driver rejects with EINVAL	wemeet-v4l2fix.so LD_PRELOAD shim (§3.5)
wemeet picture has a rolling horizontal seam	TRTC reads the mapped buffer during encode, racing the producer's next write into the same shared memory	driver serves freshest completed slot (§3.1) + shim substitutes a private copy per buffer (§3.5)
Session "shuts down" to the login screen	wireplumber's libcamera plugin SEGV-loops on the IMX208 and takes gnome-shell down	disable the plugin (§3.4)
Machine hangs on shutdown with camera on	apps holding the camera hang on stop	toggle the feed off first (§4)
Camera works, then silently breaks after a system update	v4l2loopback-dkms package upgrade restores pristine source; next DKMS rebuild drops the patch	pacman hook re-applies it (§3.1)
GNOME Camera (Snapshot) won't stream	broken upstream twice (pipewire provider gone; camerabin vs locked loopback format)	use kamoso/guvcview instead (§6)

One-shot install via an AI agent

You don't have to follow the steps manually. Point your AI coding agent (Kimi Code, Claude Code, Cursor, Aider…) at this repo — it contains everything needed, including CLAUDE.md with machine-readable internals. Paste this:

Clone https://github.com/ComradeSanta/pixelbookgo-archlinux-camera and set up
the camera on this Pixelbook Go running Arch Linux. Follow README.md: build
and install the patched libcamera (part 1), install the color fix (part 2,
including the anti-flicker tuning), then set up the v4l2loopback virtual
camera for WeChat/wemeet (part 3: driver patch + pacman hook, feed service
with the auto-dgain watcher, and the wemeet shim). Add the libcamera packages
to IgnorePkg in /etc/pacman.conf. Verify each layer works before moving on
(verify-camera.sh, cam -l, a test frame from the virtual camera).

The agent will need sudo access for package installs, DKMS and modprobe.

---

0. Why the camera is broken out of the box

The Pixelbook Go has a Sony IMX208 sensor behind an Intel IPU3 ISP. Out of the box on Arch:

1. libcamera refuses to initialize the sensor — no IMX208 sensor-helper or properties entry exists upstream, so cam -l shows nothing and no app sees a camera. (The kernel imx208/ipu3_* modules themselves load fine.)
2. With the sensor registered, the picture is nearly black with wrong colors — the IPU3 IPA falls back to an empty uncalibrated.yaml, and libcamera's AGC never touches the IMX208's digital_gain register.
3. Most video-call apps (WeChat, wemeet) can't use the IPU3 camera anyway: they only understand plain UVC-style /dev/video* devices, so a v4l2loopback virtual camera fed by the real sensor is required — and wemeet additionally trips over quirks in v4l2loopback ≥ 0.13 that other apps tolerate (see §5).

1. Part 1 — make the camera exist (libcamera patch)

Patches libcamera 0.7.1 with the IMX208 sensor helper + properties (from Peter Lishov's upstream patchwork submission, build-fixed).

cd imx208-ipu3-camera-fix/arch/libcamera
makepkg -si          # builds and installs the patched libcamera 0.7.1
../../imx208-ipu3-camera-fix/verify-camera.sh   # or: ../verify-camera.sh from inside arch/libcamera

verify-camera.sh should print all [ OK ] and exit 0.

Important: tell pacman not to clobber the patched libcamera on upgrades. Add to /etc/pacman.conf:

IgnorePkg = libcamera libcamera-ipa libcamera-tools libcamera-debug libcamera-docs gst-plugin-libcamera python-libcamera

Details and Fedora/other-distro instructions: imx208-ipu3-camera-fix/README.md.

2. Part 2 — fix the picture (tuning + digital gain)

The imx208.yaml IPA tuning file plus a script that pushes the sensor's digital_gain (libcamera's AGC doesn't control it).

The tuning file also fixes 50 Hz mains flicker: its exposure curve pins the exposure time at 10 ms — exactly one flicker cycle (100 Hz intensity) — so indoor lighting no longer makes the picture pulse; the AGC just varies gain within the pinned window. In 60 Hz countries change 10000 to 8333 in the tuning file.

The pinned window is only 8× wide (10 ms × analogue gain 1–8), scaled by digital_gain. A fixed value can't cover both a bright afternoon and a dim evening — when the scene falls outside the window the AGC leaves the 10 ms pin and banding returns. imx208-auto-dgain.sh is a small watcher (started by the feed service) that polls the sensor and steps digital_gain up/down so the exposure stays pinned across all lighting.

cd imx208-camera-color-fix
sudo ./install.sh

This installs the tuning file, a user systemd service (imx208-dgain.service) and a suspend/resume hook. Verify:

cam -c1 -I 2>&1 | grep "Using tuning file"   # .../ipa/ipu3/imx208.yaml

Details (Chinese): imx208-camera-color-fix/README.md.

3. Part 3 — virtual camera for WeChat / Tencent Meeting

Apps like WeChat and wemeet read plain /dev/video* devices, so we run a gstreamer feed from the real sensor into a v4l2loopback device.

3.1 Install and patch v4l2loopback

sudo pacman -S v4l2loopback-dkms gstreamer gst-plugins-good gst-plugin-libcamera

v4l2loopback 0.15 allows only one capture-side owner per device, which breaks real-world usage (an app that probes the camera on one fd and captures on another gets EBUSY; two apps can't share the camera). This repo ships v4l2loopback-shared-capture.patch which fixes three things:

• shared capture: tokenless capture consumers may open, S_FMT, REQBUFS, QUERYBUF, QBUF, DQBUF, STREAMON, poll and read while a producer streams — several apps can read the camera at once
• live-camera delivery: capture DQBUF always returns the freshest completed slot instead of the oldest unread one. The producer recycles slots FIFO, so the freshest slot is rewritten furthest in the future — slow consumers (wemeet's TRTC engine reads its buffer during encode) otherwise land exactly on the slot the producer is memcpy()ing into, producing a torn frame whose seam slowly rolls up the picture
• full-pool mapping: consumers may map the whole allocated pool (up to max_buffers)

Apply it and rebuild for all installed kernels:

sudo ./apply-v4l2loopback-patch.sh    # idempotent: patch + dkms build/install --force

DKMS keeps the patched source in /usr/src, so the patch survives kernel updates automatically — but a reinstall/upgrade of the v4l2loopback-dkms package itself restores the pristine source. Install the pacman hook so the patch is re-applied automatically in that case (without it, the next kernel update would silently build an unpatched module):

sudo cp pacman/v4l2loopback-shared-capture.hook /etc/pacman.d/hooks/

(Manual equivalent of the script: cd /usr/src/v4l2loopback-0.15.4 && sudo patch -p1 < …/v4l2loopback-shared-capture.patch, then sudo dkms build v4l2loopback/0.15.4 -k "$(uname -r)" --force && sudo dkms install … --force.)

3.2 Load the module at boot

echo v4l2loopback | sudo tee /etc/modules-load.d/v4l2loopback.conf
echo 'options v4l2loopback devices=1 card_label="Virtual Camera" exclusive_caps=0 max_buffers=8' \
  | sudo tee /etc/modprobe.d/v4l2loopback.conf
sudo modprobe v4l2loopback && sudo chmod 666 /dev/video0

(The pixel_formats=NV12,YUYV option seen in older guides no longer exists in 0.15.x — passing it is harmless but ignored.)

3.3 Install the feed service

The feed pipes the real sensor (1280×720 NV12) through videoconvert to YUYV 1280×720@30 — the one format wemeet's TRTC engine reliably accepts.

cp v4l2loopback-gst.sh ~/.local/bin/ && chmod +x ~/.local/bin/v4l2loopback-gst.sh
cp imx208-digital-gain-fix.sh ~/.local/bin/ && chmod +x ~/.local/bin/imx208-digital-gain-fix.sh
mkdir -p ~/.config/libcamera/ipa/ipu3
cp ipa/ipu3/imx208.yaml ~/.config/libcamera/ipa/ipu3/   # anti-flicker tuning
cp systemd/v4l2loopback-camera.service ~/.config/systemd/user/
systemctl --user daemon-reload
# Deliberately NOT enabled: a running feed keeps the sensor (and its LED) on.
# Start/stop it with vcam-toggle.sh / the "Toggle Virtual Camera" menu entry.

3.4 WirePlumber stability fix (required!)

PipeWire's libcamera plugin (libspa-libcamera) segfaults on the IMX208, crash-loops wireplumber, and takes gnome-shell down with it (looks like a shutdown — you land back at the GDM login screen). Disable it — the physical camera is used via the gstreamer feed instead:

mkdir -p ~/.config/wireplumber/wireplumber.conf.d
cp wireplumber/51-disable-libcamera.conf ~/.config/wireplumber/wireplumber.conf.d/
systemctl --user restart wireplumber

3.5 The wemeet shim (required for Tencent Meeting)

wemeet's TRTC engine sends per-frame DQBUF/QBUF with v4l2_buffer.memory = 0; v4l2loopback rejects anything but V4L2_MEMORY_MMAP with EINVAL, and the camera stays black while other apps work. wemeet-v4l2fix.c is an LD_PRELOAD shim that rewrites the field. The shim also fixes TRTC's second quirk: it keeps using the mapped buffer after DQBUF while encoding, racing the producer's next write into that same shared memory (a torn frame with a slowly rolling seam — the driver patch in §3.1 already serves the safest slot; as a second layer the shim substitutes a private copy of each buffer, refreshed synchronously at every DQBUF, so TRTC's late reads stay clean):

gcc -O2 -shared -fPIC -o wemeet-v4l2fix.so wemeet-v4l2fix.c -ldl

The stock 腾讯会议 menu entry is overridden at user level by wemeetapp.desktop (installed into ~/.local/share/applications/ by install-desktop.sh, shadowing the system one) with Exec=env LD_PRELOAD=...wemeet-v4l2fix.so /opt/wemeet/wemeetapp.sh %u so the normal icon gets the fix — no separate shortcut.

4. Shortcuts and daily use

./install-desktop.sh    # menu entries: Toggle / Enable / Disable Virtual Camera

Daily flow:

1. 开关虚拟摄像头 (Toggle Virtual Camera) → feed starts, LED lights (also applies the digital-gain fix and cycles wireplumber)
2. Open WeChat / 腾讯会议 / any camera app
3. Toggle again to turn it off — LED goes out

vcam-on.sh / vcam-off.sh (module load/unload + diagnostics) remain as the full-control variants.

5. How it works (architecture)

IMX208 ──CIO2──> IPU3 IMGU ──NV12──> libcamera (patched, tuned imx208.yaml + dgain)
                                        │
             gstreamer: libcamerasrc → videoconvert → YUY2 1280×720@30
                                        ▼
                          v4l2loopback (patched) /dev/videoN
                          "Virtual Camera"
                    ┌───────┼──────────────┬─────────────┐
                 WeChat   wemeet        guvcview      Chrome, mpv…
                 (v4l2)  (+LD_PRELOAD   (v4l2)
                          wemeet-v4l2fix)

Three pieces had to be fixed at different levels; all three are in this repo:

• driver (v4l2loopback-shared-capture.patch) — multiple apps can consume one loopback; consumers can map the whole buffer pool
• userspace shim (wemeet-v4l2fix.so) — wemeet's memory=0 bug
• feed (v4l2loopback-gst.sh) — YUYV 1280×720@30, the format wemeet wants

6. App compatibility & daily workflow

App	Works?	Notes
WeChat	✅	reads /dev/videoN directly; nothing special needed
Tencent Meeting (wemeet)	✅	only via the LD_PRELOAD shim (wired into the stock icon by wemeetapp.desktop)
guvcview	✅	direct V4L2; install guvcview. Takes photos/videos
Chrome/Chromium	✅	uses V4L2 directly
mpv/ffplay	✅	mpv av://v4l2:/dev/videoN for a quick preview
OBS Studio	✅	add a Video Capture Device (V4L2) source
GNOME Camera (Snapshot 50)	❌	broken upstream twice: (1) panics without the GStreamer pipewiredeviceprovider, which pipewire ≥ 1.6 no longer ships; (2) its camerabin negotiates formats the locked loopback can't do. Don't use it for now
PipeWire-native apps	⚠️	PipeWire's libcamera plugin is disabled (it segfaults on the IMX208 — see §3.4). PipeWire sees the virtual camera via V4L2 instead

Physical camera exclusivity: libcamera allows exactly one client of the IMX208 at a time. When the feed runs, the sensor is busy — that's the point of the loopback: unlimited apps share the virtual device. For a libcamera-native app (qcam, cam, gst libcamerasrc), toggle the feed off first.

One virtual camera, many apps: with the driver patch in §3.1, several apps may read the virtual camera simultaneously. Without it, only one app at a time could open it.

7. Files in this repo (root)

File	Purpose
vcam-toggle.sh / vcam-toggle.desktop	daily on/off for the feed (LED follows)
vcam-on.sh / vcam-off.sh (+.desktop)	full module load/unload + diagnostics
v4l2loopback-gst.sh	the actual gstreamer pipeline (→ ~/.local/bin/)
systemd/v4l2loopback-camera.service	user service that runs the feed
imx208-digital-gain-fix.sh	initial digital_gain at feed start (→ ~/.local/bin/)
imx208-auto-dgain.sh	watcher: adapts digital_gain to keep exposure pinned at 10 ms in any lighting (run by the service)
ipa/ipu3/imx208.yaml	anti-flicker tuning: exposure pinned to 10 ms (→ ~/.config/libcamera/ipa/)
wireplumber/51-disable-libcamera.conf	stop wireplumber's libcamera SEGV loop
v4l2loopback-shared-capture.patch	driver patch: shared capture consumers
apply-v4l2loopback-patch.sh + pacman/*.hook	apply/rebuild the driver patch; hook auto-re-applies it when the DKMS package is upgraded
wemeet-v4l2fix.c / .so	LD_PRELOAD shim fixing wemeet's black camera
wemeetapp.desktop	user-level override of the stock 腾讯会议 icon (adds the shim)
install-desktop.sh	install the GNOME menu entries

8. Troubleshooting

Symptom	Likely cause / fix
cam -l shows no camera	patched libcamera not active (§1); check IgnorePkg after upgrades
Picture dark/washed out	color fix not applied (§2); check tuning file + digital_gain
Picture pulses/flickers indoors	50 Hz mains flicker — §2 tuning pins exposure to 10 ms; verify journalctl --user -u v4l2loopback-camera shows Using tuning file …/.config/libcamera/ipa/ipu3/imx208.yaml (60 Hz countries: use 8333 µs)
Flicker only in dim rooms	scene outside the pinned window — the imx208-auto-dgain.sh watcher should re-pin it; check it's running (pgrep -f auto-dgain)
Rolling horizontal seam in wemeet	stale-slot tearing — pre-§3.1 driver or wemeet launched without the shim (§3.5)
wemeet camera black	launched without the shim — install the icon override (./install-desktop.sh) and use the stock 腾讯会议 icon; verify with WEMEET_V4L2FIX_LOG=/tmp/fix.log
App says camera busy	pre-patch v4l2loopback (§3.1) — re-apply the driver patch + dkms
Session "shuts down" to login screen	wireplumber's libcamera plugin crash — apply §3.4
guvcview fails to start stream	pre-§3.1 driver; also try -b (disable libv4l2)
Camera LED always on	feed running — toggle off (vcam-toggle.sh); the service is intentionally not auto-enabled
Reboot hangs with camera on	stop the feed first (the toggle also restarts wireplumber, which is the component that hangs)

License

MIT (project scripts). Upstream patches keep their original licenses (libcamera patch: Peter Lishov; original Fedora guide: Mason Zhang).