ExoPlayer's DefaultLoadControl was built with hard-coded durations picked from
one memory tier, so read-ahead stopped at 50s on any device reporting 2GB or
less free, with no way to raise it. On hardware where mpv cannot render at all
that ceiling is the whole buffer budget.
Playback Buffer offers Auto, Large and Extra Large. The durations are taken
from jellyfin-androidtv and jellyfin-android so the same words mean the same
thing across Jellyfin clients; Auto keeps the memory-tiered values that
shipped. Named tiers rather than a duration because a duration would be a
promise the load control cannot keep: prioritizeTimeOverSizeThresholds is
disabled, so targetBufferBytes stops the loader even below minBufferMs and the
byte cap binds first above roughly 23 Mbit/s.
The tier crosses the method channel as a string and resolves in the core,
where an unrecognised name falls back to Auto. LoadControlPolicy clamps the
resulting pair: media3 validates the ordering with Guava Preconditions, an
unconditional throw R8 does not elide, so a bad pair would be an
IllegalArgumentException out of player construction rather than a bad buffer.
The two play-start thresholds stay fixed even though the Jellyfin tiers move
them. BufferingStallPolicy.MIN_BUFFER_AHEAD_MS is a const derived from
BUFFER_FOR_PLAYBACK_AFTER_REBUFFER_MS, so a runtime value there would make the
stall watchdog indict a player that is obeying its own load control.
That leaves the byte target as a second, often smaller ceiling, and nothing
surfaced either. The resolved values now reach getStats, and the overlay's
Buffer section gains a Cache Limit row reading "120s / 128MB" next to the
buffered-ahead duration, so a tier that appears to do nothing on a
high-bitrate file explains itself.
close#1816
On Auto, Dart derives a buffer size for mpv's demuxer from the device heap and
sets it as `demuxer-max-bytes`. The Android player forwarded that same number to
`DefaultLoadControl.setTargetBufferBytes`, so ExoPlayer's sample allocator was
sized by a tier table written for a different consumer: 64MB on any device whose
large heap is 512MB or less, which every Shield is.
`targetBufferBytes` is a byte cap, so the media it represents collapses as
bitrate rises — 64MB is 53s of a 10 Mbit/s stream but 5.2s of a 103 Mbit/s UHD
remux. With `prioritizeTimeOverSizeThresholds` false the cap is hard:
`shouldContinueLoading` returns false the moment the allocator reaches it no
matter how little media that is, and `shouldStartPlayback` reports READY off the
same byte term. Read-ahead that short starves the audio sink in bursts, and on a
passthrough route that is enough to keep the AudioTrack from ever starting — the
track initializes, accepts one access unit and never renders a frame. Because an
enabled audio renderer owns the MediaClock, the whole player freezes and the
black-screen watchdog then blames the video decoder and drops the session to
mpv.
Size the LoadControl target natively instead, from what actually bounds
`DefaultAllocator`: the Java heap. `min(media3's own default for a video+audio
selection, largeMemoryClass/4, availMem/4)` with a 32MB floor, the lowest tier
that has already shipped. The quarter matches the threshold the Buffer Size
setting already warns at, and the media3 default is a ceiling — this is not
"buffer more than upstream", it is "stop buffering less". Deliberately not
bitrate-aware, because the LoadControl is built during initialize, before any
media is opened. `bufferSizeAuto` carries the distinction over the channel;
`bufferSizeBytes` still travels with it because the plugin's mpv fallback
replays it as a real demuxer property, and an explicit Buffer Size choice is
still honoured verbatim.
Confirmed against the hardware in the 2.9.1 passthrough report. That reporter's
own log is a natural A/B: three runs at 64MB fail with `0 frames rendered after
8002ms`, spanning both DV conversion modes and both tunneling states, while the
single run after he manually selected 128MB logs `Position advancing` and
renders. Reproduced on the same Shield model with codec and bitrate held fixed
and only the cap varied — 6s of audio demand stalls at 64MiB and plays at
128MiB, 4 of 4 predictions, with read-ahead measured off an injected
DefaultAllocator at 65 664 and 131 776 KiB. That device reports
`dalvik.vm.heapsize` 512m, so the heap term binds first at every free-memory
level in his log and Auto now derives exactly the 128MB he had to pick by hand;
the shipped path logs `Buffer: 128MB limit (auto, heap=512MB, available=568MB)`
where it previously logged 64MB.
edde746