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.
dtourolle
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