The Android port of the Apple client's stage-4 deadline discipline, closing
the side-by-side feel gap (both clients 120 Hz; Android released decoded
buffers the instant they appeared, with zero vsync awareness — the latch
phase inherited every network+decode jitter and bursts queued behind the
display).
The presenter (async loop only; the sync loop stays the untouched escape
hatch behind the Low-latency toggle):
- decode/vsync.rs: an AChoreographer thread (dlsym'd like the other
above-floor symbols) publishing the panel's vsync grid + frame timelines
(postVsyncCallback, API 33; postFrameCallback64 fallback on 31/32) and
ticking the decode loop's event channel. Started lazily on the first
decoded frame.
- decode/presenter.rs: a newest-wins slot (Lowest latency, default) or a
1-3 frame smoothing FIFO with preroll/underflow re-arm (Smoothness) between
decode and release; a glass budget of exactly ONE undisplayed release in
flight, reopened at the target timeline's DEADLINE (SurfaceFlinger's latch
— reopening at present time would halve the sustainable rate) with a 100 ms
stale force-open backstop; the release itself via
releaseOutputBufferAtTime(expectedPresent) so the latch phase is
deterministic. debug.punktfunk.presenter=arrival sysprop restores the
legacy path for a rebuild-free on-device A/B.
- Metrics: DisplayTracker is now always-on and carries the release stamp, so
the display stage splits into pace (decoded→release) + latch
(release→displayed); a 1 Hz pf.present logcat line (released/displays/
paced/noBudget/forced/qDry + pace/latch p50/max + measured vsync) makes a
HUD-off wireless A/B readable; nativeVideoStats grows to 30 doubles
(26=paceP50, 27=latchP50, 28=presents, 29=presenterActive; 0-25 frozen)
and the DETAILED HUD prints the split + presents.
- Intent parity: present_priority/smooth_buffer — the Apple client's
stored values and labels — as globals, profile-overlay fields (round-trip
+ scope markers), and Settings pickers under Decoding; threaded through
nativeStartVideo into the presenter config.
Verified: cargo ndk check/clippy clean for arm64 (the two type_complexity
warnings are pre-existing audio/mic ones), armv7 via the kit gradle task,
host cargo check clean, rustfmt clean, gradle :app/:kit unit tests all pass.
On-device before/after on the Nothing Phone 3 still owed.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
enricobuehlerandClaude Fable 5
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