Expose pixel ratio of the captured surface while screensharing. This feature will help applications to conserve their system resources or adapt the quality/bandwidth trade-off according to the physical and logical resolutions of the captured surface.
This feature allows applications using screen capture to save resources by sending the video of a screen capture using their logical, or device independent, resolution. It is common for a screen to have zoom applied via the operating system. We refer to the resolution before applying the zoom as the logical resolution. An video-conferencing application can save resources by sending the video of the screen capture at the logical resolution by removing the zoom applied to it, and reapplying the zoom after receiving it on the remote side. Since the logical resolution is normally lower than the actual/physical resolution, the application can save bandwidth and CPU when sending the video using this resolution.
Explainers: https://github.com/guidou/mediacapture-extensions/blob/main/explainer-pixels.md