Quick Media Switching (QMS)
Quick Media Switching uses a supported HDMI variable-refresh mechanism to reduce interruption during compatible frame-rate changes at a retained resolution.
Quick Media Switching, or QMS, addresses a specific interruption: a supported HDMI source changes the video presentation rate while retaining the applicable resolution and other compatible signal conditions.
It uses a supported variable-refresh mechanism to avoid the ordinary blackout associated with re-establishing that rate change.
Rate changes can have a narrower scope than mode changes
A trailer can have a different source cadence from the feature that follows it. Without a suitable seamless-switch route, the source can either preserve a fixed output cadence or change its output mode and allow the link/display to re-establish.
QMS gives a supported arrangement another option for the relevant rate-switch case.
| Original switch exercise | Relation to the published QMS scope |
|---|---|
| 3840 × 2160 at 24 Hz → same resolution at 60 Hz, otherwise compatible | A rate-change case to examine for QMS support |
| 1920 × 1080 → 3840 × 2160 | Resolution changes; the basic QMS promise does not establish seamless operation |
| SDR presentation → PQ/HDR presentation | Other interpretation/mode changes; QMS alone does not establish seamless operation |
The table illustrates scope, not tested devices.
VRR and QMS are related but distinct claims
HDMI LA describes QMS using a VRR mechanism. That does not mean every device exposing VRR implements the required QMS feature or every player uses it.
The source, display and any intermediate receiver need the compatible route. Application/OS integration also determines which output change is actually requested.
Frame-rate matching explains why the player might want a rate change. VRR explains the underlying variable timing relationship.
The observed switch is the useful evidence
For an Emby transition, record the before/after output rates, resolution and HDR state. A blackout involving several simultaneous mode changes cannot be attributed to QMS rate handling alone.
An app’s refresh-rate switching support is not automatically a declaration that it uses QMS on every compatible TV. A stable-rate presentation also cannot demonstrate a rate-switch feature because no such switch occurred.