Files
LlamaCasty/Helpers/index.md
T
gramps 55ca1029a3 UNIT 0: make a dropped webcam frame measurable, not just inferable
The creator is DHH and lipreads their own recordings, so a webcam that
judders is an accessibility defect, not a polish item. Take
ty-20261005-1001-821-0001.mp4 holds 25.6 distinct webcam images/s against
the camera's 30fps with 281 gaps of 50-100ms - roughly one hitch in five -
in a file that muxes flawlessly. Nothing in the app could see that: rawvideo
carries no per-frame timestamps (ffmpeg stamps by ARRIVAL at the declared
60fps), and the stats line divided every average by the number of frames
SUBMITTED, which deadline padding always fills to the full target. So the
pump reported "300/300 frames, avg render 12.4ms" while producing 60
distinct composites.

Helpers/FrameCadence.cs is one pure counter fed from three points:
MediaCaptureFrameSource logs the device's own SystemRelativeTime stamps
against our arrival times (TryAcquireLatestFrame keeps only the LATEST
frame, so falling behind is silent by design), and FramePump logs the
distinct webcam Epoch values that reached a composite. Read together they
name the culprit - device/USB, our reader, or our compositor - instead of
guessing. Render/resolve/wait now divide by the real render count, and
"frames per 5s from R renders" is the duplicate-on-lag ratio stated
honestly.

An out-of-order timestamp counts as a frame but produces no gap and does not
become the next interval's reference, so one bad stamp cannot invent a
multi-second hitch twice.

Also corrects a stale ai.md line (the "webcam renders at ~18fps" figure
came from a different session and counted every newly rendered layer) and
re-records the background-removal ruling as permanently out. Records the
agreed-but-unbuilt Units 1-2, the no-fallback-camera ruling, and the
SetFormatAsync dead end found by probing the 19041 projection.

Suite 402/402, 0 warnings. The one red, LayerReorderPersistenceTests'
RealMouseDrag, fails identically on a stashed clean tree - it needs an
interactive desktop session this shell lacks.
2026-10-05 11:10:22 -07:00

2.1 KiB

Helpers — index

Cross-cutting utilities. See schema.md for the memory-map conventions.

File Purpose
ViewModelBase.cs INotifyPropertyChanged + SetProperty<T>() — base for all ViewModels
RelayCommand.cs ICommand implementation for all button actions
AppLog.cs File logger to %APPDATA%\ytLlive\startup.log; startup checkpoints + unhandled-exception capture (the crash this map is named for)
FocusPreservingListBox.cs ListBox subclass that keeps selection/focus coherent when the selected item is deleted; IsSelectable predicate skips hidden scenes; drag-reorder guard
OAuthCredentials.cs Baked-in Google OAuth client ID/secret (desktop app; loopback callback)
TokenStore.cs DPAPI-protected OAuth session persistence (%APPDATA%\ytLlive\ytLlive.auth, CurrentUser scope); Save/Load/Clear — sign-in survives restarts
ImageCache.cs Image byte caching (assets live in the DB)
InverseBoolToVisibilityConverter.cs / NotNullToVisibilityConverter.cs XAML value converters for visibility bindings
AllTrueToVisibilityConverter.cs Multi-value AND-gate → Visible; gates the layer-row capture menu items on row-IsBackground + staged-scene-is-Live (TASK 25)
CameraConflictProbe.cs Best-effort diagnostic: when a camera won't start, enumerates running processes known to hold cameras (OBS, Zoom, Teams, NVIDIA Broadcast, browsers, etc.) — Windows doesn't expose "which process has this device" via any public API, so this is a suspect list, not a verdict
FrameCadence.cs Pure arrival-cadence counter (FrameCadence + FrameCadenceSummary.Describe): frames, gaps, hitches, longest/avg gap for a window of a timestamped stream. Fed by MediaCaptureFrameSource (camera stamps vs our arrivals) and FramePump (distinct webcam Epochs that reached the output) — UNIT 0, see ai.md "Frame cadence"

Related: Themes/Controls.xaml styles the lists this class backs; Models/index.md and ViewModels/index.md for the objects it works on.