mirror of
https://github.com/lhns/steam-frame-nix.git
synced 2026-10-06 05:00:24 +02:00
Pierre Kisters
5a3d0b9d05
The README is the complete user documentation again: features, install, two sessions, usage, the full options table (and renamed options), every feature with problem, usage, limitations, security and "remove when", UI patches at user level (DevTools on the LAN, after a Steam update), changes outside Nix, rollback and uninstall. docs/ keeps only the technical side (how the patches work, writing patches, signatures and the update procedure, the SteamVR debugger mechanics, cleanup and installer internals), linked from each feature. docs/options.md, two-sessions.md and desktop-integration.md are gone (their content is in the README).
50 lines
2.0 KiB
Markdown
50 lines
2.0 KiB
Markdown
# Jellyfin hardware decoding: how it works
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`jellyfin.hardwareDecoding.*` (module `jellyfin`). What it does, how to
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configure it and its caveats: README,
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[Jellyfin hardware decoding](../README.md#jellyfin-hardware-decoding-jellyfinhardwaredecoding).
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## Why mpv doesn't use the decoder
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The Frame's hardware decoder is a V4L2 memory-to-memory device
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(`qcom-iris`, `/dev/video*`), which
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- the Flatpak can't open: its `devices=dri` covers only the GPU, and Flatpak
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has nothing between that and `devices=all`;
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- mpv never tries: Jellyfin hard-sets `hwdec=auto-copy`, and mpv's `auto`
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probing leaves out V4L2 M2M on purpose (its quality varies by SoC).
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Jellyfin has no way to pass mpv options.
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## The shim
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An `LD_PRELOAD` shim (`modules/jellyfin/mpv-hwdec-shim.c`, a few libmpv
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wrappers, only libc) rewrites an `hwdec` value starting with `auto` (set
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through libmpv's `mpv_set_*` functions) to `$SFN_MPV_HWDEC` (the `hwdec`
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option); explicit values such as `no` stay. It is preloaded from the Nix
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store; only its store path is exposed (read-only) to the sandbox. It would
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work for any libmpv app that sets `hwdec=auto*`, but only Jellyfin Desktop
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is set up here.
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## The desktop entry
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Nothing is written to Flatpak's overrides: a desktop entry shadowing the
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Flatpak's (`~/.local/share/applications/org.jellyfin.JellyfinDesktop.desktop`,
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same ID, so the KDE menu and the "+" menu start it) passes device access and
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the shim as `flatpak run` options, so they apply to launches from that entry
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and are gone with it:
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```sh
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flatpak run --branch=stable --arch=aarch64 --command=jellyfin-desktop \
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--device=all --filesystem=<shim>:ro \
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--env=LD_PRELOAD=<shim>/lib/mpv-hwdec-shim.so \
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--env=SFN_MPV_HWDEC=v4l2m2m-copy,auto-copy org.jellyfin.JellyfinDesktop
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```
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(The exact line with the store path is the read-only option
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`steamFrame.jellyfin.hardwareDecoding.command`.)
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Older versions used a Flatpak override (via nix-flatpak or a Home Manager
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link) and a shim copy in `~/.var/app/org.jellyfin.JellyfinDesktop`;
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`steam-frame-nix-cleanup` removes their entries from the override and the
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copy.
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