A paired video plays and its clock advances, but nothing of it reaches the screen unless the panel simulation is on.
Measured. Same paired sequence and video, same build, only panelMode changed. Sampling a row across the region where the video's test pattern should be:
| panelMode |
distinct colours in the sampled row |
video visible |
FIT_PHYSICAL |
3 (white / black stripes present) |
yes |
OFF |
1 (uniform black) |
no |
Why. The translucent surface plus alpha-from-brightness is applied on the panel path. With no panel there are no apertures, the matrix is drawn as a filled raster, and it covers the video surface underneath it completely.
Consequence. panelMode OFF is the cheapest render and the obvious thing to pick on a slow device, or when someone just wants flat pixels. Pairing a video with a sequence then silently does nothing visible, which reads as the video being broken rather than as a mode interaction.
Fix direction. The full-screen path needs the same treatment as the panel path when a video is underneath: translucent surface, and per-pixel alpha from the strongest colour channel so unlit pixels pass the video through. Substrate is already understood to be mutually exclusive with video showing through.
Found while measuring #26.
A paired video plays and its clock advances, but nothing of it reaches the screen unless the panel simulation is on.
Measured. Same paired sequence and video, same build, only
panelModechanged. Sampling a row across the region where the video's test pattern should be:FIT_PHYSICALOFFWhy. The translucent surface plus alpha-from-brightness is applied on the panel path. With no panel there are no apertures, the matrix is drawn as a filled raster, and it covers the video surface underneath it completely.
Consequence.
panelMode OFFis the cheapest render and the obvious thing to pick on a slow device, or when someone just wants flat pixels. Pairing a video with a sequence then silently does nothing visible, which reads as the video being broken rather than as a mode interaction.Fix direction. The full-screen path needs the same treatment as the panel path when a video is underneath: translucent surface, and per-pixel alpha from the strongest colour channel so unlit pixels pass the video through. Substrate is already understood to be mutually exclusive with video showing through.
Found while measuring #26.