The long-deferred Android display stage (design/stats-unification.md; plan 4.1 of
design/client-parity-and-network-resilience.md): AMediaCodec_setOnFrameRenderedCallback
(API 26, under the minSdk-28 floor ⇒ hard-linked via ndk-sys) reports SurfaceFlinger's
per-frame render timestamp, giving the HUD the spec's `display` = decoded→displayed term
and the directly-measured capture→displayed end-to-end headline on both decode loops.
Falls back per spec to the v1 capture→decoded endpoint on any window without render
callbacks (the platform may drop them under load), and to it permanently if registration
is refused.
- The render timestamp arrives on CLOCK_MONOTONIC; it's re-based onto CLOCK_REALTIME
against monotonic-now at callback time, which also cancels the (batchable) callback
delivery lag.
- The `ndk` crate exposes neither the callback nor the codec pointer needed to bind it
raw, so the workspace pins `ndk` 0.9.0 to a vendored copy (clients/android/native/
vendor/ndk) whose ONLY change makes MediaCodec::as_ptr public — the "as_ptr patch".
Workspace-excluded so host builds never compile it; drop when upstream exposes either.
- nativeVideoStats grows to 26 doubles (22–25: dispValid, displayP50, e2eDispP50/P95;
0–21 unchanged for older readers); StatsOverlay moves headline endpoint + equation
together so the equation always tiles the headline interval.
Verified: host cargo check/test/clippy, aarch64-linux-android check/clippy, Kotlin
app+kit+tests compile, roborazzi HUD render shows the full 4-term equation. Device
verification rides plan 4.2's phone A/B.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
