Four builds (89/90 + two) burned proving the alert video was PERFECT: real h264
1280x720, 240 frames decoded, alert audio in the live mix, and the shipped asset
byte-identical (md5 0ee1f496…) to the creator's llamacasty-dancingLlama-thankyou.mp4
with every sampled frame full bright content. Build 90's new diagnostics then showed
the frame reaching BOTH consumers every second for the whole clip —
`Alert preview: frame=680x200 a255` and `Output resolver: frame 680x200
playing=True` — an opaque, correctly-sized frame, handed over and never seen.
Root cause: Controls/PreviewPane.xaml keeps the per-element Image Collapsed unless a
DataTrigger fires, and there was no IsAlertBox trigger (only IsImageSource / IsChatBox /
IsWebSource / IsWebcam). The alert box's Image was therefore Collapsed forever. Chat
boxes rendered because they HAVE a trigger — that asymmetry is the whole clue, and it
is why removing/re-adding the layer could never fix it.
Fix: an IsAlertBox DataTrigger beside the IsChatBox one.
Two Good Dog tests, because the existing fakes had been hiding this:
- AlertBoxPreviewVisibilityTests (red `Expected: Visible / Actual: Collapsed`, now
green) drives the real MainWindow + PreviewPane and asserts the bound Image is
Visible — the first alert test that crosses the XAML at all.
- AlertClipOutputTests is the first test in the repo to run a REAL codec: pinned ffmpeg
generates a clip, the real AlertClipDecoder + AlertOverlayLayer + SceneCompositor
composite it, and the box rect must be a colourful picture that DIFFERS from idle. It
passed while the feature was broken in the app — which is exactly why it was needed:
it exonerated decode+layer+compositor and pointed the hunt at the last hop.
Also keeps the two once-per-second alert diagnostics (resolver + preview) that settled
it, pending the creator's call on whether to keep them.
Notes: the pinned BtbN ffmpeg has no libx264, so the test clip is -c:v mpeg4.
SceneCompositor.Render fills its base with opaque black, so the test compares against an
idle render rather than counting non-zero bytes. MediaSource has the same missing trigger
in PreviewPane.xaml — left unfixed as out of scope, noted in HANDOFF.
Full suite 324/324. Lesson recorded in MyMistakes.md rule (5): a producer that hands over
a correct frame has still delivered nothing — when output arrives and the user still sees
nothing, stop auditing the producer and audit the consumer's VISIBILITY.
The 12:35 live session proved the decoder healthy (frames=240 audioChunks=156
failed=False both clips, alert audio in the mix at peakMix 0.277→0.733) yet the
creator still saw 'no video plays / you lost the video'. Root cause: pacing,
not decode. AlertClipDecoderFor built the decoder with no frameRateProbe, so
RunAsync computed frameDuration = TimeSpan.Zero and RunVideoAsync's pace step
was dead code — all 240 frames of the 10s clip dumped through the pipe in the
first ~1-2s (130MB as fast as ffmpeg read), then the box froze on the LAST
frame while audio chunk-paced its real-time ~7.8s. Reads exactly like a dead
decoder on screen. The media path already wired this seam
(MainViewModel.cs:308); the alert factory never supplied one.
Derivative fix (media/decoder plumbing, cited in broad consensus of players):
pass FfmpegFrameRateProbe into the per-play alert decoder exactly like
MediaVideoSource does. Good Dog:
AlertClipDecoderTests.AlertClipDecoder_PacesVideoFramesToTheProbedFrameRate —
real AlertClipDecoder via the fake-process/fake-probe/delay-recorder seam;
red on the old factory (zero pacing delays), green with the probe (one ~10ms
delay per frame at 100fps). Full suite 321/322, one known-env flake
(RealMouseDrag reorder). Docs in this commit: task-47 addendum,
MyMistakes.md (a decoder that drops data faster than wall-clock looks
identical to a dead one), HANDOFF rewrite.
Routing and ruling both good: 'procs in the chat windows but nothing in the alert box'
with zero exceptions — every failure stage was silent by design (Debug.WriteLine-only
preview catch, bare catch{} in RunAsync firing Completed regardless). A decode run that
starts but yields neither a frame nor an audio chunk left _clip != null with
_latestClipFrame == null, so RenderClipFrame returned null forever: the box stayed
transparent for the whole alert and the six-animation fallback (which only ran on
setup-time throws) never fired.
Fix: AlertOverlayLayer.Advance gives a started clip a NoFrameFallbackSeconds (1.0s)
grace — produce no frame AND no audio inside it and the clip is torn down, _elapsed
resets, and the SAME alert continues as the animation branch (never blank, never drained
early). Diagnostics stop the lying silence: BeginClip logs box id/path/size + setup
failures; AlertClipDecoder.RunAsync logs frame/chunk end-state and the exception it used
to swallow.
Good Dog test: SilentDecoder_FallsBackToTheAnimationAfterTheNoFrameGrace (transparent
inside grace, disposed past it, animation renders, drains to idle).
Reference: alert playback must degrade to its fallback on dead-air, never vanish —
same contract as every player/booth failure budget (e.g. OBS source fallbacks).
https://obsproject.com/forum/threads/source-visibility-fallback.187383/
Live test session proved the native alert box DID play (the alert ring was the
only source in the mix: micLevel/loopLevel 0.000 while peakMix went
0.375->0.733->0.891 after the sim injections) but the app crashed at
11:22:01.301 the moment a REAL message round-tripped through the poller:
System.ArgumentException: Must create DependencySource on same Thread as
the DependencyObject
at ...MS.Internal.Data.DataBindEngine.ProcessCrossThreadRequests()
OnMessageReceived ran RefreshAlertPreviews on the MTA poller thread and
stamped the WPF-bound VideoImageSource with a WriteableBitmap created there;
the binding engine's cross-thread re-bind killed the process. ChatOverlayLayer
already marshals this exact seam (Dispatcher.Invoke) - mirror it, guarded for
Application.Current null so the pure test seams still run inline.
Good Dog test:
AlertLayerVideoTests.OnMessageReceived_FromPollerThread_MarshalsPreviewWritesToTheUiThread
calls the seam from a raw MTA Thread while the RealApp loop runs, then asserts
on the UI thread that the preview bitmap's Dispatcher is the App's (red on the
old seam, green on the fix). WPF cross-thread rule recorded in MyMistakes.md.
Full suite 320/320, clean build 0 warnings, scope-check green.
TASK 43's alert box grows a real video celebration. Per-alert IAlertClipDecoder
(ffmpeg bgra + f32le pipes, real-time paced, disposed at drain) plays the shipped
Assets/alert-default.mp4 (stamped into the Asset table at startup) unless the
creator picks their own file — path reference only, never stored in the DB; the
six AlertRenderer animations stay the fallback. ~0.3s fade rides the alpha
envelope on straight-source copies (EOF freeze-frames then fades out); audio
forwards to a new AudioMixer alert ring (8s, 48k stereo) drained at unity — no
duck, creator ruling — scaled by volume × fade. An auto-composed marquee ticker
('Funder — Super Chat · $10.00', 140px/s) scrolls top-of-frame via a
FramePump._alertTicker seam through Render/CompositeLayers, mixed into the cache
signature (dynamic overlay, never baked). New Stream Alerts section in LeftPanel.
Derivative-work references (how OBS/Streamlabs alert boxes do per-alert video):
- https://support.streamlabs.com/hc/en-us/articles/217741147-Setting-Up-Your-Streamlabs-Alerts (custom image/video per alert type + variations)
- https://obsproject.com/kb/stream-tutorial-2-alerts (alert overlay as an on-screen zone)
- https://streamlabs.com/content-hub/widgets/alert-box (per-event alert playback)
Good Dog: AlertLayerVideoTests drives a fake IAlertClipDecoder through the whole
lifecycle in one pass (custom path wins, decoder spawns/disposes, fade envelope
0→127→255, audio volume×fade, ticker scrolls, EOF fade-drain to idle). It caught
the clip branch of Advance not clearing _current before AdvanceToNext — the layer
stayed IsPlaying after drain (MyMistakes post-mortem).
Full vstest 319/319; clean build 0 warnings; scope check green.
gramps