Extracting an embedded subtitle track walks the interleaved container:
subtitle packets sit between video and audio across clusters, so
harvesting a few KB of text means demuxing that stretch of a multi-GB
file off CephFS. Over 41.6h the web player saw p95 120,021ms / max
121,470ms on /api/v1/stream/{session_id}/subtitles/{track}, with 45 of
220 fetches over 10s. The 120s ceiling is the server's absolute
WriteTimeout (cmd/silo/main.go:2389) cutting the body mid-flight -- and
because WriteHeader(200) already ran, those truncations are logged
status=200 and are invisible in error metrics.
The server believes a 600s window bounds this. It does not: -t is passed
as an input option and ffmpeg silently ignores it for these extracts, so
every request runs from the seek point to EOF. Measured against the
production binary, `-ss 4000 -t 30` and `-ss 4000 -t 300` are
byte-identical to passing no -t at all (last cue 02:10:04, end of film).
Only -ss works, so cost tracks (duration - seek) x bitrate.
The window cannot simply be turned on. silo-apple and silo-android both
fetch a track once and depend on receiving the whole thing, so bounding
the output would silently kill subtitles ~10min into every film on both
platforms. The accidental whole-track behaviour is the de-facto contract.
So: keep whole-track delivery, make it cheap. SubtitleCache already had
the right shape for PGS; text was excluded only by the assumption that
"VTT is already windowed and fast", which the inert -t makes false.
Windowing a cached 83KB VTT costs 52ms versus 16s against the original
27GB remux.
Routing on AllowWindow would have poisoned the cache: it is set only in
the PGS branch, so it is always false for text, while streamExtractArgs
applies -ss to any non-ASS/non-PGS source regardless. A seeked subrip
request would take the full-track path, emit seek->EOF, exit cleanly and
publish that partial as canonical -- and every later viewer from 0 would
lose all cues before it (118 of 143 production requests carry a non-zero
seek). Canonicality is now derived from the effective argv instead:
streamExtractPlanFor is the single source of truth for both the argv and
the partial() predicate, so only a seek=0/duration=0 extract can fill.
- key: adds a schema version and the resolved output profile (an ASS
source is reachable as both .ass and .vtt, so format must be keyed)
- removeStaleSiblings now groups by profile, so committing .vtt no longer
deletes a valid .ass sibling; cleanup and eviction no longer hardcode
.sup, so text entries are reclaimed and counted
- InputIsExtractedTrack carries the cached input's format
- text hits use a plain copy with no-store, matching cold-path HTTP
semantics; ServeContent stays on the PGS path only, since Media3 uses
range-capable data sources and responses must not vary with cache warmth
- renames SUP-specific identifiers now that the cache carries text
The inert -t is deliberately retained and its comment corrected in place:
removing it or moving it after -i would bound the output and break the
native clients.
Latency-only: for every (source codec, requested format, seek) the bytes
a client receives are unchanged.
Rationale, measurements, four superseded revisions and the dead ends are
recorded in docs/superpowers/plans/2026-07-17-subtitle-extract-cache.md.
AI-use disclosure: investigated and implemented with AI assistance
(Claude Code + Codex gpt-5.6-sol); Codex's review caught the cache-
poisoning bug above.
Silo
Silo is a self-hosted media streaming server for your movies, shows, music, and books. Point it at your media folders and stream to your devices — at home or away — with direct play, remuxing, and hardware-accelerated transcoding handled automatically.
Join the community on Discord. If Silo is useful to you, consider sponsoring the project — see Supporting Silo.
Highlights
- Plays your media, your way — direct play when the device supports it, remux or hardware-accelerated transcode (including NVENC) when it doesn't.
- Web app included — a full-featured web client and admin interface ship with the server.
- Works with apps you already use — optional Jellyfin/Emby-compatible API supports clients such as VidHub, Findroid, and Infuse.
- Household profiles — multiple profiles per account, with per-profile watch state and parental controls.
- Plugin-driven metadata — match and enrich your libraries with providers like TMDB and TVDB, installed as plugins.
- Fast setup — one
docker compose up -dbrings up the whole stack; everything else is configured in the admin UI.
Deploy with Docker (recommended)
The easiest way to run Silo is with Docker Compose. The default stack assumes you do not already have PostgreSQL and Redis available, so it bundles PostgreSQL, Redis, FFmpeg, and the application for a one-command start.
-
Create a
.envfilecp .env.example .env -
Set your media path
Edit
.envand set:MEDIA_ROOT=/path/to/your/mediaMEDIA_ROOTis the one value most users need to change. You can also overrideSILO_DATA_ROOTif you do not want bind mounts under/opt/silo, and change ports if the defaults conflict with something else on the host. -
Start the default integrated stack
docker compose up -dThis starts PostgreSQL, Redis, and the integrated Silo server. The app is available at
http://localhost:8090. Jellyfin-compatible app support is disabled until an administrator enables it in onboarding or admin settings.If you already have PostgreSQL and Redis available, omit those bundled service examples from compose and point Silo at your existing
DATABASE_URLandREDIS_URLinstead.Optional NVIDIA/NVENC
GPU support is kept out of the default compose file so hosts without NVIDIA drivers work unchanged.
Install the NVIDIA Container Toolkit and use a Docker Compose version with GPU reservation support before enabling this override.
Use the optional override file when you want NVENC:
docker compose -f docker-compose.yml -f docker-compose.nvidia.yml up -dIf you want this controlled from
.env, setCOMPOSE_FILE:COMPOSE_FILE=docker-compose.yml:docker-compose.nvidia.yml NVIDIA_GPU_COUNT=1Windows uses
;instead of:between compose files.Then
docker compose up -dwill include the NVIDIA override automatically. -
Configure through the admin UI
Add libraries, users, metadata providers, and playback settings from the web interface.
Bind Mount Layout
The deploy-oriented compose files use host folder mappings rather than Docker-managed volumes.
By default, data is stored under /opt/silo:
/opt/silo/postgres/opt/silo/redis/opt/silo/transcode/opt/silo/catalog-seeds
Media is mounted into the container at /mnt/media from the host path you set in MEDIA_ROOT.
Optional Profiles
The main compose file is integrated-first. These profiles exist for operators testing distributed mode or mirroring a split deployment shape. Most single-host installs should stay on the default integrated service, because it already includes proxying and transcoding.
| Profile | Command | Description |
|---|---|---|
| default | docker compose up -d |
Integrated server plus bundled PostgreSQL and Redis |
proxy |
docker compose --profile proxy up -d |
Start a standalone proxy service for distributed-mode testing |
transcode |
docker compose --profile transcode up -d |
Start a standalone transcode service for distributed-mode testing |
You can enable both optional examples together:
docker compose --profile proxy --profile transcode up -d
If you are splitting workers across multiple hosts, use the separate remote worker example instead of trying to stretch the main compose file across machines.
Advanced Remote Node Example
For a dedicated remote transcode worker, use docker-compose.remote-transcode.yml. That file is intended for a separate worker host that connects back to an existing Silo deployment using shared PostgreSQL and Redis.
Deployment Notes
The default compose stack intentionally bundles PostgreSQL and Redis for ease of setup and assumes a fresh install without those services already available. If you already operate PostgreSQL and Redis, omit those examples from compose and point Silo at your existing infrastructure instead. For serious installs, PostgreSQL is better on a separate VM or a managed service so upgrades, tuning, and backups are isolated from the app host. Redis can stay local for many installs, but externalizing it is also reasonable if you already operate shared infrastructure.
Silo is externally stateful by default rather than fully stateless. Durable application state lives in PostgreSQL. Redis only stores coordination and cache-style data. Silo still writes transient transcode output locally under /tmp/silo-transcode. If you switch userdb.backend=sqlite, Silo also becomes locally stateful at /var/lib/silo/userdb.
Migrating an existing Continuum Docker install should be done with the preflight helper and cutover guide in docs/continuum-to-silo-docker-migration.md.
Configuration
Silo requires only a DATABASE_URL when running from source or against external infrastructure. In the default Docker Compose path, the stack wires the database and Redis URLs for you. All other settings — libraries, metadata providers, transcoding, users — are managed through the admin UI after first launch.
Server Modes
| Mode | Description |
|---|---|
integrated |
Full server: API + frontend + scanner + transcode (default) |
api |
API server only, no local transcoding |
proxy |
Stream proxy node that connects to the shared deployment database and Redis |
transcode |
HLS transcode worker node that connects to the shared deployment database and Redis |
PostgreSQL Auto-Tuning
The default Docker Compose stack does not require a checked-in postgresql.conf.
It enables Silo's pgtune-style OLTP tuning
by default:
POSTGRES_TUNE: auto
When enabled, Silo connects with DATABASE_URL and applies recommendations with
ALTER SYSTEM, which writes to PostgreSQL's postgresql.auto.conf inside the
database data directory. Reloadable settings are applied immediately with
pg_reload_conf(). Settings that PostgreSQL marks as restart-only are written
too, and Silo logs the setting names so you can restart PostgreSQL once:
docker compose restart postgres
The default Compose database user has the required PostgreSQL permissions. If
you use an external PostgreSQL server, make sure the configured DATABASE_URL
user can run ALTER SYSTEM, or set POSTGRES_TUNE=off and manage
PostgreSQL yourself.
For POSTGRES_TUNE_MEMORY=auto, Silo uses the first trustworthy memory source:
a finite Docker cgroup limit, the read-only /host/proc/meminfo mount supplied
by the bundled Compose file, then /proc/meminfo with container safety guards.
Auto-detected memory is treated as a PostgreSQL budget, defaulting to 75% of
detected RAM so Silo, Redis, plugins, transcodes, and the OS retain headroom.
POSTGRES_TUNE_DB_SIZE=auto queries pg_database_size(current_database()) and
classifies the workload by comparing the database size to that memory budget.
Optional tuning overrides:
| Variable | Default | Description |
|---|---|---|
POSTGRES_TUNE_PROFILE |
oltp |
Tuning profile. Only oltp is currently supported. |
POSTGRES_TUNE_MEMORY |
auto |
Server/container RAM, such as 8GB or 32GB; explicit values are used as-is. |
POSTGRES_TUNE_MEMORY_BUDGET_PERCENT |
75 |
Percent of auto-detected RAM used for PostgreSQL recommendations. |
POSTGRES_TUNE_CPUS |
auto |
CPU count used for worker recommendations. |
POSTGRES_TUNE_STORAGE |
ssd |
One of hdd, ssd, san, or nvme. |
POSTGRES_TUNE_DB_SIZE |
auto |
Use less_ram when the database comfortably fits in RAM, mid_ram, or greater_ram for very large databases. |
POSTGRES_TUNE_CONNECTIONS |
100 |
PostgreSQL max_connections; automatically raised if Silo's app pool is configured higher. |
POSTGRES_SHM_SIZE |
8gb |
Docker /dev/shm size for the bundled PostgreSQL container. |
Advanced operators can still supply their own PostgreSQL configuration or
override these env vars. Set POSTGRES_TUNE=off when you do not want Silo to
change PostgreSQL server settings. Settings already written with ALTER SYSTEM
remain in postgresql.auto.conf; reset those PostgreSQL parameters if you later
move fully to a custom postgresql.conf.
Build from Source
If you prefer running Silo without Docker:
-
Install prerequisites: Go 1.24+, Bun 1.0+, PostgreSQL 18+, and FFmpeg.
-
Start PostgreSQL and Redis (skip if you already have them running)
docker compose up -d postgres redisThe main compose file still expects
MEDIA_ROOTto be set even if you only want the bundled PostgreSQL and Redis services, so set that in.envfirst. -
Configure the database connection
cp .env.example .envEdit
.envand setDATABASE_URLto point to your PostgreSQL instance. -
Build and run
make build ./siloThe server starts at
http://localhost:8080by default. All other settings are configured through the admin UI.
Reporting Issues
Client implementers can use the Canonical Settings API guide for contract discovery, contextual headers, remote scopes, effective reads, and the admin projection.
If you are reporting a bug, install problem, or performance issue, start with the admin workflow and reproduction steps, not Claude/Codex analysis.
Please include:
- What you were trying to do
- Exact steps you took
- What you expected to happen
- What actually happened
- What exact action is slow or broken (
save,scan,browse,import,playback, etc.) - Whether it happens every time or only sometimes
- The library, media type, filter, setting, or value involved
- Version, branch, commit, and deployment details if you know them
- Screenshots, recordings, or log snippets if relevant
If you used Claude/Codex for debugging, put that under Technical notes at the end. Suspected files, SQL output, stack traces, and root-cause theories can be helpful, but only after the workflow and repro steps are clear.
Use this template:
Goal:
Steps:
Expected:
Actual:
What is slow/broken:
Scope:
Version/branch:
Deployment:
Technical notes:
Contributing & Development
Silo is open source and contributions are welcome. See DEVELOPMENT.md for building from source in a dev workflow, running tests, database migrations, and project layout, and CONTRIBUTING.md for contribution expectations, merge request guidance, and the policy for AI-assisted submissions.
Supporting Silo
Silo is an open-source hobby project, developed in spare time and funded out of pocket. If you'd like to support development, you can sponsor via GitHub Sponsors.
Donations go directly toward the costs of building and running the project:
- AI development tooling subscriptions (Claude, Codex) used to build and maintain Silo
- Push notification relay infrastructure
- Future development costs
Sponsoring is entirely optional — Silo is and will remain free and open source. Bug reports, contributions, and feedback are just as valuable.
License & Trademarks
Silo's source code is licensed under the GNU Affero General Public License
v3.0 or later (AGPL-3.0-or-later) — see LICENSE.
The Silo name, logo, and wordmark are trademarks of Silo Media L.L.C. and are not covered by the AGPL. You're free to fork and redistribute the code, but forks and redistributions must not use the Silo brand as their identity and must remove or replace the brand assets. Publishing a Silo-branded app to an app store requires written permission. See TRADEMARK.md for what's permitted — including referential use like "compatible with Silo."