Commit Graph
3 Commits
Author SHA1 Message Date
dtourolle 11d9d760d8 feat(player): native video on Linux, and one contract for every player (v0.11.0)
mpv now decodes video on Linux, drawn into a framebuffer we own and blitted
into the default vbox's draw handler. Tauri's widget tree is untouched, so an
upgrade that assumes its own layout cannot invalidate this. Direct play means
the original file, hardware decoding, and no server transcode at all — where
previously every desktop video was re-encoded to h264 for the browser engine,
whatever the file actually was. Off by default: JELLYTAU_NATIVE_VIDEO=1.

That settles finding 2 of playback-backend-unification.md — "native video
cannot be composited with a Tauri webview" — by demonstration rather than
argument, on X11 and Wayland both.

Turning it on exposed nine defects, none of them mpv's. Each was the same
mistake in a different place: a capability written down as a compile-time fact
about the platform, or a state asserted instead of confirmed.

  DR-238/246  a seek routed by the stream's container rather than by what the
              engine could do with it - correct only while one player handled
              those streams, silent the moment another did
  DR-239      a property handled but never observed, so the play/pause button
              waited for an event that could not arrive
  DR-240      fullscreen expanding the document while the window stayed put
  DR-241      a seek issued before the engine had a file, failed, and discarded
              - which is why resume began at zero
  DR-247      a Linux-only gate outliving the caller that made it Linux-only,
              breaking the Android build outright
  DR-250      a stop aimed at whichever renderer bookkeeping believed was in
              charge, missing the one actually making sound
  DR-251      a duration of zero believed, leaving the seek bar no scale
  DR-252      a junk float converted to a Duration, panicking the backend the
              instant a length-less stream appeared

So the MediaPlayer contract (DR-242 … DR-247): `open` carries a start position,
so no caller sequences load-then-seek and none can race an engine's load;
`seek` states a destination and leaves in-place-versus-re-open to the engine;
`snapshot` is one coherent read; and `Phase::Opening` names the window where
intent used to be lost. One conformance suite runs against every engine —
FakePlayer and mpv under cargo test, ExoPlayer instrumented on a device — so an
engine is either correct or visibly failing.

Two of the nine were introduced during this work and caught on hardware, not by
any suite: an over-broad capability that grouped ExoPlayer with mpv, and the
Duration panic. The suites test engines that behave. That is recorded in
docs/native-player-verification.md, which asks for the exact action sequences
that found them.

Verified: all automated gates, conformance (mpv 9/9, legacy 8/9 by design,
ExoPlayer 7/7 on device), and manual desktop and Android passes on real
hardware.

Known open and deliberately shipped: resume reads local progress and never the
server's; the background-audio handoff still declares a state swap it does not
confirm (the symptom is now impossible, the race is not); and `bun run
android:dev` builds an APK carrying the release application id, whose failure
message advises an uninstall that would destroy app data. Fix that last one
before anyone else builds for Android.

Squashed from worktree-linux-native-video, which keeps the per-defect history.
2026-08-23 10:51:45 +02:00
dtourolle 99d96163d8 docs(specs): correct the spike's crash and ABR findings
Three corrections to the Linux native-video spike, each of which reverses
something recorded earlier in the same session:

- The crash is unexplained. It was first blamed on hwdec=auto-safe's Vulkan
  failures, on a misreading of the logs — those are two per run at start-up,
  not per-frame, and every clean run has the same two. A 300s soak on
  auto-safe survived. So did 240s of automated fullscreen toggling (~120
  transitions) and 240s of continuous resizing (~2000 reallocations). Three
  hypotheses, none reproduced. Recorded rather than dismissed: an
  intermittent fault nobody can reproduce is worse to inherit than a
  deterministic one.

- G5 drops to amber. It looked and felt smooth, but the only SIGSEGV observed
  came from the only session in which fullscreen was exercised, and the spike
  has no lifecycle handling at all — it never frees the render context. An
  implementation must bind that to the GL context's lifetime regardless of
  what caused this crash, because Android already paid for that lesson as
  DR-184.

- Finding 3's premise is in doubt. "The webview path already has real ABR via
  hls.js" was never checked against the URLs this app builds:
  get_video_stream_url requests a single rendition, the frontend has no
  level-handling code at all, and a quality switch is implemented by
  re-opening the stream. If the playlist is single-variant there is no
  adaptation to lose. The decisive test needs a live server and is recorded
  as unrun.

Also records hardware decode working through the render API (nvdec-copy
engaged), and that hwdec=vaapi silently fell back to software on this box.
2026-08-21 19:41:21 +02:00
dtourolle f11f5eddd5 docs(specs): record the Linux native-video compositing spike
🏗️ Build and Test JellyTau / Run Tests (pull_request) Successful in 15m3s
🏗️ Build and Test JellyTau / Supply Chain (pull_request) Successful in 38s
Traceability Validation / Check Requirement Traces (pull_request) Successful in 20s
🏗️ Build and Test JellyTau / Android Compile Check (pull_request) Successful in 4m11s
Adds the spike write-up and re-opens finding 2 of
playback-backend-unification.md, which concluded that video cannot unify
on a native engine because the webview owns the surface.

That finding's general form has since been falsified on Android, where
native video composites behind a transparent WebView and ships on by
default. The evidence behind it was also entirely about foreign-window
embedding -- mpv's render API, drawing into a GL context we own inside
Tauri's own GTK tree, was never tested. The spike tests that one claim
and comes back green on Linux for both X11 and Wayland, bar the Tauri
default_vbox() half of G1.

Findings 3-6 are deliberately left standing. Finding 3 in particular --
mpv has no adaptive bitrate -- is an independent disqualifier that a
green compositing result does not clear, and the spike says so rather
than reading as a green light.

The next-free-id line moves to UR-079 / IR-033 / DR-219: this branch
allocated UR-077 and UR-078 for the updater and diagnostics work, and
DR-215 through DR-218 with them, after that line was last written.

Authored in a parallel session working in the same checkout; committed
here so it travels with the rest of the branch.
2026-08-21 19:06:13 +02:00