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.
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.
dtourolle