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Command

Several config sections run an external process from a command: the proxy stream, segmenter and error handlers, and the channel playout. They all share the same shape and templating rules, described here.

A command is configured with three fields, all optional:

Field Type Description
command array or string The program and its arguments.
template_variables []NameValue User variables available in the command as {{ .name }}.
env_variables []NameValue Environment variables set for the process.

Forms

command is an array of strings: the program followed by its arguments, each a separate element. Every element supports Go template syntax with Sprig functions.

command:
  - "ffmpeg"
  - "-v"
  - "{{ .log_level }}"
  - "-i"
  - "{{ .Stream.PlaylistPath }}"

The first element is the program; the rest are its arguments.

Template Variables

Two kinds of variables are available inside a command:

  • User variables — anything you define in template_variables, referenced as {{ .name }}. Sections that ship a default command document their own defaults (e.g. width, fps, segment_duration); override them by name. Where a section cascades (Global ➡ Playlist ➡ Channel), template_variables are merged by name across levels.
  • Reserved variables — injected by majmun at runtime (see below).

Reserved Variables

Majmun injects a set of namespaced variables at runtime. They are always available in the command (no need to declare them) and are also exposed to the process as MAJMUN_-prefixed environment variables, so wrapper scripts can read them without templating.

Template variable Environment variable Available in Description
{{ .Stream.URL }} MAJMUN_STREAM_URL segmenter Upstream stream URL
{{ .Stream.SegmentPath }} MAJMUN_STREAM_SEGMENT_PATH segmenter, playout Segment filename pattern (e.g. /tmp/.../seg_%05d.ts)
{{ .Stream.PlaylistPath }} MAJMUN_STREAM_PLAYLIST_PATH segmenter, stream, playout HLS playlist path (e.g. /tmp/.../stream.m3u8)
{{ .Playout.Input }} MAJMUN_PLAYOUT_INPUT playout Path of the file to play now
{{ .Playout.Offset }} MAJMUN_PLAYOUT_OFFSET playout Seek position (seconds) into the file; empty at start
{{ .Playout.VideoCodec }} MAJMUN_PLAYOUT_VIDEO_CODEC playout The file's video codec (e.g. h264, hevc)
{{ .Playout.Width }} MAJMUN_PLAYOUT_WIDTH playout Coded video width in pixels (as stored)
{{ .Playout.Height }} MAJMUN_PLAYOUT_HEIGHT playout Video height in pixels
{{ .Playout.AspectWidth }} MAJMUN_PLAYOUT_ASPECT_WIDTH playout Width corrected for the sample aspect ratio (square-pixel, even-rounded); use as the scale_vaapi width
{{ .Playout.PixelFormat }} MAJMUN_PLAYOUT_PIXEL_FORMAT playout Video pixel format (e.g. yuv420p)
{{ .Playout.FrameRate }} MAJMUN_PLAYOUT_FRAME_RATE playout Video frame rate as a fraction (e.g. 30000/1001)
{{ .Playout.FieldOrder }} MAJMUN_PLAYOUT_FIELD_ORDER playout Field order (progressive, tt, bb, …); for deinterlace decisions
{{ .Playout.AudioCodec }} MAJMUN_PLAYOUT_AUDIO_CODEC playout First audio stream codec (e.g. aac)
{{ .Playout.AudioChannels }} MAJMUN_PLAYOUT_AUDIO_CHANNELS playout First audio stream channel count
{{ .Playout.SampleRate }} MAJMUN_PLAYOUT_SAMPLE_RATE playout First audio stream sample rate in Hz
{{ .Playout.AudioLanguages }} MAJMUN_PLAYOUT_AUDIO_LANGUAGES playout Space-separated language tag of each audio stream, in order (und when untagged), e.g. eng rus und
{{ .Channel.Name }} MAJMUN_CHANNEL_NAME playout The channel's name
{{ .Channel.Logo }} MAJMUN_CHANNEL_LOGO playout The resolved logo ("" when unset)
{{ .Playlist.Name }} MAJMUN_PLAYLIST_NAME playout The parent playlist's name

Environment variable names are the namespace and field flattened to upper SNAKE_CASE (Stream.PlaylistPath → MAJMUN_STREAM_PLAYLIST_PATH). Empty values are not exported. User template_variables are not exported as environment variables — use env_variables for that.

Reserved namespaces

Stream, Playout, Channel and Playlist are reserved and cannot be used as template_variables names. Setting one is a validation error.

Inline or Script

Because the reserved paths are available as environment variables, a long command can live in a shell script instead of inline YAML, which is often more readable:

command: [ffmpeg, -i, "{{ .Stream.PlaylistPath }}", -c, copy, -f, mpegts, "pipe:1"]

command: [/config/scripts/stream.sh]

#!/usr/bin/env bash
exec ffmpeg -i "$MAJMUN_STREAM_PLAYLIST_PATH" -c copy -f mpegts pipe:1

Both run the same program. The inline form keeps everything in one file and supports the template_variables cascade; the script form trades that cascade for plain shell variables and keeps the YAML short. A script must be executable (chmod +x), readable inside the container, with its interpreter and any tools (e.g. FFmpeg) on PATH.

Use exec in wrapper scripts

End the script with exec ffmpeg ... (as above), so FFmpeg replaces the shell and majmun can stop it directly. Without exec, FFmpeg is left orphaned when majmun terminates the script.