dtourolle
109700b949
Playing a video meant asking the server to re-encode it, always. That
decision was made nowhere and written down nowhere, so whoever needed it
re-derived it downstream — the player worked out whether it had been handed
a playlist by looking for ".m3u8" in the URL, in two places. A viewer paid
for a transcode of a file their device could have played untouched, and the
app could not tell them which it was.
One negotiation now produces one self-describing StreamSelection — direct
play, remux or transcode; over a playlist, a plain HTTP file, or a local one
— and every renderer consumes that same answer.
Measured against the development server (Jellyfin 10.11.5), 400 items
sampled for codec mix and 40 put through a real PlaybackInfo negotiation
per profile:
Linux / WebKitGTK (h264 only, 2ch) 3/40 — 7% direct play
Android / ExoPlayer (hevc, ac3/eac3, 6ch) 34/40 — 85% direct play
The library is ~80% hevc, which is why the two diverge so hard. The payoff
is overwhelmingly Android, where 85% of plays were starting a transcode
nobody needed. Linux stays near 7% until libmpv decodes the picture — the
h264-only profile is a WebKitGTK constraint, not a JellyTau choice.
DR-219 StreamSelection: url + tagged Transport (hls/progressive/localFile)
+ PlaybackKind (directPlay/directStream/transcode) + the negotiated
rendition + this source's ladder + a needs_transcoding flag derived
in Rust so the rule is answered once. Both enums are serde-tagged
so the frontend matches a discriminant, not a substring. The paths
that never negotiate get the same shape from Rust rather than
assembling one — media_local_selection for a downloaded file,
LiveStreamInfo.transport for a live channel — so there is no second
place where a transport is decided.
DR-220 The ceiling becomes two levels: a durable device default (Settings,
persisted) and a per-playback override the in-player picker sets.
The picker had called itself a "this film, this connection" control
since it was written but wrote the process-wide default, so dropping
one awkward film to 2 Mbps silently capped every video played
afterwards for the rest of the process, with Settings still showing
the old value. The override is cleared whenever playback moves to a
new item, which stops it surviving into an autoplayed next episode.
effective_streaming_quality() is the single resolution point.
DR-221 The quality picker is filled from what this media source can offer.
Rust marks a rung exceeds_source when its ceiling is at or above the
source's own bitrate — such a rung is another way to spell Original
— and the frontend does not draw those. Original is never marked; a
source whose bitrate the server does not report marks nothing, which
keeps every rung offered.
DR-222 Direct play and direct stream are negotiated, with two client-side
overrides on top because the server's answer is right about the file
and wrong about what this app will do with it: undecodable audio
(Jellyfin 10.11.5 honours a DirectPlayProfile's container and video
codec but ignores its audio codec, so it offers direct play for an
E-AC-3 track the webview renders in silence) and a viewer-pinned
audio track the file does not default to. A direct stream is a remux
and is deliberately not counted as transcoding.
DR-223 Dropped on measurement, not deferred. A master playlist from this
server carries exactly one EXT-X-STREAM-INF: Jellyfin builds it from
the single rendition the request asked for rather than publishing a
ladder. So there is no adaptation for hls.js to be preserving and
none mpv would lose — the claim that there was, in
playback-backend-unification.md, does not hold. Recorded rather than
deleted because it is a measurement: a server that does publish a
ladder would change the answer.
DR-224 Every backend consumes the same selection. The queue item carries
the transport, so player_seek_video picks its seek strategy from the
backend's decision instead of the last stream_url.contains(".m3u8")
in the codebase. Items queued by a path that never negotiated carry
None and fall back to needs_transcoding, which is exact rather than
a guess because every transcode this app requests is HLS (DR-140).
The frontend loader decision moves to streamTransport.ts so it can be
tested: the two cases that pin it are the ones that failed against the old
implementation — a progressive stream whose URL contains ".m3u8" must not
get an HLS loader, and an HLS stream whose URL contains none must.
Also verified the URL the direct-play branch builds actually serves playable
bytes: 206, video/mp4, valid ISO-BMFF, and a mid-file range works, so
seeking a direct play works.
The spec is folded into docs/architecture/{01,02,03} and deleted, per the
rule that docs/specs holds only work that has not shipped. DR-121 leaves
read-through-media-cache.md with a pointer; that spec keeps its capture half.
Not verified: real playback on a device. Direct play changes what actually
gets played, and neither fixtures nor curl prove the WebKitGTK and ExoPlayer
paths render it.
JellyTau
A cross-platform Jellyfin client built with Tauri, SvelteKit, and TypeScript.
Business logic lives in a Rust backend; a UI-rich Svelte frontend handles presentation and talks to it over Tauri's IPC. Targets Linux (libmpv) and Android (ExoPlayer).
Getting Started
This project uses bun as its package manager.
# Activate the Rust environment (fish shell)
source "$HOME/.cargo/env.fish"
# Install dependencies
bun install
# Run in development
bun run tauri dev
# Type-check the frontend
bun run check
# Build for Linux
bun run tauri build
# Build for Android
bun run tauri android build
For the full set of build, test, and Android helper scripts, see scripts/README.md.
Documentation
| Topic | Location |
|---|---|
| Architecture overview & subsystem docs | docs/architecture/ |
| Requirements, traceability & technical debt | docs/requirements.md |
| Build & release process | docs/build/build-release.md |
| Docker builds | docs/build/docker.md |
| Traceability tooling & CI | docs/traceability.md, docs/traceability-ci.md |
| Release checklist | docs/release-checklist.md |
| UX flows | docs/ux-flows.md |
| CI operations (builder image, secrets, runner) | docs/build/ci-operations.md |
Contributing
CONTRIBUTING.md covers the setup, the gates a change has to pass, and the two rules that catch people out (bug fixes start with a failing test; Jellyfin's taxonomy stays in Rust). Please also read the Code of Conduct.
Found a security problem? Do not open an issue — see SECURITY.md.
Verifying a download
Every release publishes SHA256SUMS covering all of its artifacts, plus an SBOM
of what went into the build:
sha256sum -c SHA256SUMS
Desktop builds update themselves from Settings → Updates, verifying each payload against JellyTau's signing key before installing. Android installs are handled by the system installer, so the app links to the releases page instead.
Recommended IDE Setup
VS Code + Svelte + Tauri + rust-analyzer.
License
MIT