Emby Theme Maker

An Emby Server plugin that turns Emby's Intro Detection markers into per-series theme videos (backdrops/theme.mp4) and theme music (theme.mp3) — using the server's own built-in ffmpeg. No external tools, no API key.

It's the native-plugin evolution of an earlier command-line script: same idea, but it runs inside Emby and is driven from Scheduled Tasks.

What it does

For each TV series, the plugin:

1. Reads the intro markers (IntroStart / IntroEnd) straight from Emby's item database.
2. Picks a representative episode (median intro length — robust against cold opens / specials).
3. Cuts [IntroStart → IntroEnd] from that episode with Emby's bundled ffmpeg, re-encodes with fade in/out, and writes the result into the series folder.
4. Triggers a library scan so Emby registers the new theme media.

Output depends on the Mode setting:

Mode	Writes
Video	<SeriesFolder>/backdrops/theme.mp4 (h264/aac video backdrop)
Audio	<SeriesFolder>/theme.mp3 (theme music, series root)
Both	both of the above, in one pass

Requirements

• Emby Server 4.9.x (built/tested against 4.9.5.0, Windows & Linux).
• Intro Detection already run on your shows (that's where the markers come from).
• A bare-metal / VM install where Emby can write into your series folders. (In container/NAS setups where the series folders aren't writable by the server, it can't drop the theme files.)

No API key, no external ffmpeg — the plugin uses Emby's own item database and ffmpeg.

Install

1. Download EmbyThemeMaker.dll from the latest release (or build it — see below).
2. Drop it into your Emby plugins folder and restart the server:
   • Windows: …\Emby-Server\programdata\plugins\
   • Linux (deb/rpm): /var/lib/emby/plugins/
3. Open Dashboard → Theme Maker and configure it.

Usage

Everything runs from Dashboard → Scheduled Tasks:

• Theme Maker: Preview (read-only) - logs exactly what it would generate for each series (source episode, intro span, whether a theme already exists) without writing anything or reading STRM wrapper files. Run this first.
• Theme Maker: Generate - actually encodes the theme files, per your settings. This is the only Theme Maker task that reads a STRM wrapper, and it does so only after the episode markers and output eligibility have been checked.

Add a trigger to either (daily / interval / on startup) to run it on a schedule, or run on demand. All activity is logged to the Emby log with a [ThemeMaker] prefix.

Settings (Dashboard → Theme Maker)

Setting	Meaning
Output mode	video / audio / both
Overwrite existing themes	Regenerate even when a theme already exists (off = skip existing)
Only under this folder	Restrict to series whose folder is under this path (blank = all)
Limit	Process at most N series per run (0 = no limit)
Source episode	Median (robust) or First episode
Min / Max intro length	Ignore intros outside this range (seconds)
Pad start / end	Extend the cut before/after the markers (seconds)
Preferred audio language	e.g. jpn — picks that stream if present (blank = first)
Max video height / CRF / Preset / Peak bitrate	libx264 quality controls
Audio bitrate / Fade in / Fade out	audio + fade controls
Output filenames / backdrop subfolder	where and what to write
Parallel encodes	how many ffmpeg jobs at once (default 1; keep 1 for STRM Generate runs)
Maximum new themes per Generate run	series allowed to receive one or both configured outputs before Generate stops (default 1; existing skipped outputs do not count)
Scan library after generating	trigger one Emby scan at the end so new themes register

STRM safety

A .strm wrapper is not opened by Preview. During Generate, Theme Maker accepts a normal local media path unchanged. For a .strm file it reads at most 64 KiB as UTF-8 (an optional BOM is accepted), ignores blank lines and # comment lines, and requires exactly one absolute http or https URI. All other schemes, local paths, malformed targets, and multiple targets are skipped with a safe category. The target is passed directly to ffmpeg without a shell and is never written to Theme Maker logs, errors, or task summaries.

Migration notes

After upgrading, run the read-only Theme Maker preview first. Existing Jobs values are retained, but new installations default to one job and one successful series per Generate run. Set a deliberate per-run series cap before scheduling Generate. Existing theme.mp3 files remain protected unless Overwrite is enabled. Preview remains read-only and does not read STRM wrappers.

Safe by default: it never overwrites an existing theme unless Overwrite is on, and it never deletes a song out of a curated theme-music/ folder.

Building

Requires the .NET SDK. Targets netstandard2.0, references mediabrowser.server.core (Emby's NuGet); the Emby assemblies are provided by the host and are not bundled — the output is a single self-contained EmbyThemeMaker.dll.

dotnet publish EmbyThemeMaker/EmbyThemeMaker.csproj -c Release -o out
# -> out/EmbyThemeMaker.dll

To stamp a version, pass it in (CI does this from the git tag):

dotnet publish EmbyThemeMaker/EmbyThemeMaker.csproj -c Release -o out -p:Version=1.2.3

Releases

Pushing a tag like v1.2.3 triggers the GitHub Actions workflow, which builds the DLL, stamps it with the tag version, publishes a GitHub Release with EmbyThemeMaker.dll attached, and generates a build provenance attestation for the artifact (verifiable with gh attestation verify EmbyThemeMaker.dll --repo <owner>/<repo>).

License

GPL-3.0 — see LICENSE and COPYRIGHT.

You may use, modify, and redistribute it under the GPL-3.0. As the sole copyright holder, the author also reserves the right to offer it under separate (e.g. commercial) terms — see the dual-licensing note in COPYRIGHT.