Two independent failures were killing long unattended runs.
1. HANG at the end of a video (Windows AppHangB1)
The player froze after ~30-45 minutes of looping, always at a video item. The
playback trace stopped dead right after "video_loaded" with no "video_eos" and
no "advance_after_video_eos", and Windows logged AppHangB1 rather than a crash.
Cause, all inside Kivy and verified against the installed source:
1. ffpyplayer fires on_eos.
2. Kivy's Video widget binds its OWN handler first (kivy/uix/video.py
_do_video_load), and that handler sets state = 'stop' DURING the event
dispatch.
3. state = 'stop' -> VideoFFPy.stop() -> unload(), which calls
self._thread.join() with no timeout (the source even carries the comment
"TODO: use callback, don't block here").
4. When that decode thread is slow to exit, the Kivy/SDL main thread never
returns, so the window stops pumping messages.
It is a race, which is why it looked random and only appeared after many videos.
src/video_safety.py bounds that join. ffpyplayer has already been told to quit
and its thread woken before the join, so limiting the wait does not leak work;
it only stops an unresponsive thread from taking the whole player down. The
guard is installed before the Video widget is constructed, because the decode
thread is created during play().
The intro video had the same hazard on the main thread (state='stop' followed by
unload() inside the state callback) and is now torn down on a worker thread like
playlist videos.
2. CRASH in SDL2_mixer.dll (0xc0000005) on a video with no audio stream
Triggered when a silent 4K clip entered the playlist while the item was marked
audio: on. ffpyplayer initialises SDL2_mixer from the FIRST audio file it opens
and reuses those parameters, so a file with no audio stream (rate/channels 0)
makes SDL2_mixer dereference garbage. Muting via volume=0.0 does NOT avoid it -
the audio stream itself must be disabled.
play_video now probes the file with ffprobe and forces mute when it has no audio
track, so such a file can never reach ffpyplayer with sound enabled. The probe
fails safe (assumes audio present) if ffprobe is unavailable.
3. 24/7 supervision (solution A + C)
windows/watchdog.ps1 + start_player_watchdog.bat restart the player when it
crashes (process gone) or hangs (process alive but .player_heartbeat stale),
with a crash-loop breaker that backs off when it cannot stay up. This is the
Windows counterpart of the proven Linux start.sh watchdog.
The exit-screen password remains the only supported way to stop the player. On
success it writes .player_stop_requested next to the .exe and the watchdog
stands down instead of restarting. The flag is SESSION SCOPED: the watchdog
clears it on every start, so launching again begins a new session and there is
no file to delete by hand. Clearing on start also means a power cut cannot leave
the player permanently off.
Deliberately NOT done: a Windows service. A service runs in session 0 with no
desktop, so the player could not render to the screen at all. A login-triggered
startup entry is the correct Windows analogue of the Pi's systemd unit.
Important detail: the packaged player is TWO processes (PyInstaller bootloader
parent plus the child that owns the SDL window), so any kill uses taskkill /T or
the visible window survives and the next launch collides with it.
Verified in the packaged exe over a 7-hour run: 170 playlist restarts, 1365
items, 171 web links launched/visible/ended with zero failures, and no crashes,
no hangs and no leaked browser processes.
Tests: windows/test_video_hang.py and windows/test_watchdog.py. The hang test
deliberately holds the heartbeat open with an exclusive Windows lock (share mode
0) so the player's own write fails - backdating the file's mtime does NOT
simulate a hang, because the healthy player rewrites it immediately and the test
would then pass for the wrong reason.
13 KiB
description, name
| description | name |
|---|---|
| Use when building, compiling, packaging or releasing the Kiwy Signage Player: PyInstaller build, .exe generation, build.spec, hiddenimports, code signing, Smart App Control, Windows development, Raspberry Pi deployment, or adding new modules under src/. Covers the exact build commands, environment constraints, bundling rules and verification steps. | Kiwy Build & Development |
Kiwy Signage Player — Build & Development
Cross-platform Kivy digital signage player.
- Raspberry Pi / Linux —
src/main.pyis the entry point (rootinstall.sh,start.sh). - Windows —
windows/run_win.pyis the entry point; it sets Windows env vars, importsmain.py, then monkey-patches platform differences. Packaged to.exewith PyInstaller.
Ground Rules
- Keep
src/main.pycross-platform. Windows-specific behaviour belongs inwindows/run_win.py(see_patch_main()), Pi-specific behaviour inmain.pyguarded by capability checks. Do not add Windows-only imports tomain.py. - Rebuild is mandatory. The
.exebundlessrc/, so Python edits are invisible until you rebuild. There is no hot reload in the packaged app. dist/is a runtime folder, not just build output. It holdsconfig/,media/,playlists/,logs/,.kiosk-profile/and.player_heartbeat. Never wipedist/blindly; a--cleanrebuild preserves it, but a manual delete destroys player state.
Environment
| Item | Value |
|---|---|
| Interpreter | Python 3.12.9 (64-bit) — project venv at windows\venv |
| Kivy | 2.3.1 |
| PyInstaller | 6.21.0 |
| Linux target | Python 3.13 (repo/python-wheels/, repo/system-packages/) |
- Python 3.13+/3.14 is NOT supported for the Windows build — Kivy 2.3.1 has no wheels for them.
cefpython3is not installed in the project venv (its wheels stop at Python 3.9). The embedded-CEF engine inwindows/cef_browser.pyis therefore dormant on this build — do not rely on it.- Web links use embedded WebView2 (
windows/webview2_browser.py), driven throughpythonnet(installed). Two extra things ship with the exe:windows/webview2_sdk/— ~860 KB of SDK DLLs (Microsoft.Web.WebView2.Core.dll,WebView2Loader.dll). Tracked in git on purpose: without them WebView2 silently downgrades to the Chrome/Edge subprocess engine.windows/webview2_runtime/MicrosoftEdgeWebview2Setup.exe— ~1.7 MB bootstrapper, used to install the Runtime on a machine that lacks it. The ~203 MB offline standalone installer is git-ignored; fetch it withwindows/webview2_runtime/download_runtime_installers.ps1 -Offlinewhen you need to deploy to machines with no internet (it makes the exe ~305 MB).
Build
From windows\:
venv\Scripts\python.exe -m PyInstaller build.spec --clean --noconfirm
Or the full one-click path (creates venv, installs deps, builds, then signs):
build_win.bat
Output (folder mode, via COLLECT):
windows\dist\KiwySignagePlayer\KiwySignagePlayer.exe <- the real build output
Deployment hazard: windows\dist\KiwySignagePlayer.exe (one level up) is a stale
leftover from an older single-file build of the same name. It is not refreshed by the
current spec, so deploying it ships old code. Always take the executable from the
KiwySignagePlayer\ subfolder, and delete the stray copy if it reappears.
build.spec facts
- Entry point
run_win.py;pathex=[BUILD_DIR, SRC_DIR]sosrc/modules resolve. runtime_hooks=[pyi_runtime_hook.py]— sets per-monitor DPI awareness before SDL/Kivy initialise. Keep DPI work here; it must run before any window is created.datas += Tree(src)bundles all ofsrc/.console=Trueso startup errors and the Kivy log remain visible — do not flip this toFalsewithout a reason.hiddenimportsmust list modules that PyInstaller's static analysis cannot see: lazily imported ones (cef_browseris imported inside a function) or dynamic imports (getattr,importlib). Top-level imports such asweblink_sessionare found automatically viapathex, but listing them is harmless insurance. When you add a module undersrc/that is imported lazily or by string, add it tohiddenimportsor the packaged exe will fail at runtime withModuleNotFoundError.excluded_importsdrops Linux-only packages (evdev,gi, GStreamer) and the non-matchingcefpython3.pydvariants.
First-run setup (no bundled credentials)
config/app_config.json is deliberately NOT bundled into the exe, and
player_auth.json is excluded from Tree(src). Shipping either one planted the
build machine's server_ip / screen_name / auth_code into every install, so
a fresh machine silently connected to the wrong server (or played a stale
playlist) instead of asking.
What happens on a machine with no usable config:
- The splash video (
config/resources/intro1.mp4) plays. - A notice appears: "Player is not configured".
- After
SETUP_NOTICE_SECONDS(5 s,src/main.py) the Settings screen opens automatically. - Saving valid values writes
config/app_config.jsonnext to the .exe and playback starts immediately — no restart needed.
On a machine that is configured, the notice and Settings are skipped and the cached playlist plays straight away.
Key functions in src/main.py:
| Name | Role |
|---|---|
config_is_configured(config) |
Single source of truth. Missing file, empty/unparseable JSON, missing keys and leftover placeholders (localhost, kivy-player, 1234567, 127.0.0.1) all count as unconfigured. |
DEFAULT_CONFIG |
Blank-credential starting point, so a fresh install can never look configured. |
SignagePlayer.on_intro_finished() |
The one decision point after the splash: setup vs. playback. Both intro paths (video end and "no intro file") go through it. |
show_setup_required_notice() |
Shows the notice, then opens Settings after 5 s. |
on_first_run_config_saved() |
Re-syncs and starts playback. |
config_is_configured() is covered by windows/test_first_run_setup.py — run it
after touching that logic.
When adding a new required config key, add it to
CONFIG_REQUIRED_KEYS(and toCONFIG_PLACEHOLDER_VALUESif it has a placeholder default), or the first-run flow will not ask for it.
24/7 Supervision (Windows)
A signage player must survive crashes and hangs unattended. On Linux/Pi this is
start.sh (systemd or ./start.sh). On Windows it is windows/watchdog.ps1,
launched by windows/start_player_watchdog.bat.
It restarts the player when it:
- crashed — the process disappeared; or
- hung — the process is alive but
.player_heartbeathas gone stale (the player rewrites it every 10 s; the watchdog treats >60 s as hung). A frozen player is otherwise indistinguishable from a working one.
It also backs off if the player cannot stay up (crash-loop breaker:
CrashLoopMaxFailures failures in CrashLoopWindowMin minutes without ever
becoming healthy → CrashLoopBackoffMin minutes of quiet).
The stop flag is SESSION-SCOPED
The only supported way to stop the player is the exit-screen password. On
success the player writes .player_stop_requested next to its .exe, and the
watchdog then stands down instead of restarting.
The flag is cleared every time the watchdog starts, which is what makes it session-scoped: the password exit ends the current session, and the next launch begins a new one. There is no file to delete by hand.
Ordering matters: the flag is the operationally-correct choice over a "remember the last exit" setting, because a reboot must come back up playing. Clearing on start also means a power cut cannot leave the player permanently off.
Two failure modes that must not be confused
| Situation | Correct reaction |
|---|---|
| Was healthy, then heartbeat went stale | Restart promptly (this is a hang) |
| Running but never became healthy (slow start, bad install, the first-run setup screen) | Be patient, then restart after 2 × StartupGraceSec |
Never kill a player that has not yet been healthy — it may be an operator entering server settings on the first-run setup screen.
Important Windows-specific facts
- The packaged player is TWO processes (PyInstaller bootloader parent + the
child that owns the SDL window). Any kill must use
taskkill /Tor the visible window survives and the next launch collides with it. - The watchdog can only restart an install that already has a working config. It cannot help before the player has first run.
- Hiding the console window (
console=False) is not done: the console is the only way to see a start-up failure, and the build instructions warn against flipping it without reason. - No Windows service. A service runs in session 0 with no desktop, so the
player could not render to the screen. A login-triggered task is the correct
Windows counterpart to the Pi's systemd unit — that is what
start_player_watchdog.batis for (add it to the Startup folder for autostart).
Verify the watchdog
cd windows
venv\Scripts\python.exe test_watchdog.py # crash + hang + stop-flag + new-session
Check state at any time (read-only):
powershell -NoProfile -ExecutionPolicy Bypass -File windows\watchdog.ps1 -Status
When testing a hang, do not just backdate the heartbeat file's mtime — the healthy player rewrites it immediately, so nothing is actually stale and the test passes for the wrong reason. Hold the file open with an exclusive Windows lock (share mode 0) so the player's own write fails; that reproduces a genuine stale heartbeat while the process stays alive.
Code Signing (production constraint)
Production PCs run with Smart App Control enforced (VerifiedAndReputablePolicyState=1,
UMCI enforced) with no "Run anyway" bypass — an unsigned exe is blocked at kernel level.
- A self-signed certificate does NOT satisfy Smart App Control. A cert from a reputable
public CA is required.
create_self_signed_cert.ps1is dev-only. - Provide a cert as
KIWY_SIGN_PFX(+ optionalKIWY_SIGN_PFX_PASSWORD) or dropkiwy_signing.pfxinwindows\;build_win.batthen signs viasign_exe.ps1(signtool with RFC3161 timestamp when available). - See
documentation/CODE_SIGNING_SMART_APP_CONTROL.md.
Verify Before Committing
Fast syntax gate (no build, seconds):
python -m py_compile src/main.py src/weblink_session.py windows/run_win.py windows/webview2_browser.py windows/webview2_runtime.py
Web-link engine checks (no build, no player):
cd windows
venv\Scripts\python.exe test_webview2_embed.py # embeds WebView2 in a bare Win32 window
venv\Scripts\python.exe test_webview2_runtime.py # Runtime detection + installer discovery
Rebuild warning: the bundled offline installer makes the exe ~305 MB. If you do not
need offline machines, delete
windows/webview2_runtime/MicrosoftEdgeWebView2RuntimeInstallerX64.exe before building.
Close the running player before rebuilding. A running
dist\KiwySignagePlayer\KiwySignagePlayer.exe locks the output and the build fails with
"Access is denied". Chrome/Edge kiosk processes left over from web-link playback can also
hold locks; if the build fails, check for stray msedge.exe / chrome.exe before retrying.
Because .exe is a reserved Windows device name as well as a real file, use
Test-Path -LiteralPath when probing for the executable, otherwise the path silently
resolves to the console device.
Development run — use this on a SAC-locked host, since the unsigned exe cannot launch:
cd windows
venv\Scripts\activate
python run_win.py
Diagnose playback transitions via the trace log (logs\playback_trace.log), written by
src/playback_trace.py.
Release Checklist
- Bump
PLAYER_VERSIONinsrc/main.pyandfilevers/prodvers/FileVersion/ProductVersioninwindows\version_info.txt; keep them in sync. - Rebuild (
build_win.bat). - Confirm the exe is signed (
Get-AuthenticodeSignature); unsigned builds are blocked on production hosts. - Smoke-test a mixed playlist: image → video → weblink → image, verifying durations, audio
(
audio: off/muted), and a clean exit/restart.
Commit Hygiene
- Never commit
windows\build\orwindows\dist\(git-ignored). Tracked build output such aswindows\archive_list.txtandwindows\build_last.txtis the exception, not the rule. - Do not commit
player_auth.jsonorsrc/player_auth.json— they contain live credentials (auth_code,player_id,server_url). These are currently tracked; treat any future change to them as a deliberate, reviewed decision. - Do not commit
config\app_config.jsonvalues that are host-specific without checking whether they belong in the repo default.