Media Sources

Media sources in AURA are stored in steering and are evaluated and played by engine. Each media source object is assigned to a media object. These media objects are then referred to by other entities, like in Episode.mediaId, Schedule.defaultMediaId, and Show.defaultMediaId.

The following diagram shows the relationship between media and media source objects and contains a subset of their supported fields.

        erDiagram
    Media ||--|{ MediaSource : contains
    Media {
        string playoutMode
    }
    MediaSource {
        string type
        string source
    }

Understanding `type` and `source`

The type describes what kind of data the media source contains, whereas the source describes where the data can be obtained.

Available types

AURA currently allows three types: audio, m3u, and aura-structuredaudio.

audio is just that: audio data. Basically anything FFMPEG will handle.

m3u refers to the common M3U format, which is used for playlists, mostly of local files.

aura-structuredaudio is a special format used by AURA to store metadata for uploaded audio files. It is JSON-encoded, and the only required fields are:

path, which must contain a file system path to an audio file and
name, which must contain the name of the file.

Available sources

Currently, every source in AURA is a URL, usually one that starts with http://, https://, or file://.

Available source URL protocols depend on the type of the media source.

For the audio type, AURA supports the file://, http://, https://, and line:// protocols. file:// refers to local files on the engine host, http:// and https:// refer to audio streams accessible via HTTP, and line:// is a special protocol for local line-in devices on the engine host. They are defined in steering’s radio settings under Playout → Line in channels.

For the m3u type, AURA supports only the file:// protocol, as this is mostly intended for fallback media.

aura-structuredaudio only supports http:// and https://. This type and source combination is created when audio files are uploaded in the dashboard. In these cases the source is the URL of a file resource in battery.

A common URL pitfall

By definition, URLs expect the hostname after the protocol delimiter (://). This is also true for file:// and line:// URLs, even though a hostname doesn’t make sense for AURA in these cases.

Ensure that you add a third slash after the protocol to skip the hostname (file:///my-file.mp3, line:///3).

How `file://` URLs are resolved

Note that most of the file:// sources are interpreted as relative paths to a specific directory on the engine host. In almost all cases the type plays a role in constructing an absolute path because engine has dedicated environment variables that define base directories for audio files, file uploads, and m3u playlists.

Examples

These are examples for media sources you will often find in AURA.

An uploaded audio file:

{
  "type": "aura-structuredaudio",
  "source": "https://aura.example.org/battery/media-store/api/v2/2371"
}

An audio stream:

{
  "type": "audio",
  "source": "https://cast.example.org/stream.mp3"
}

An M3U playlist:

{
  "type": "m3u",
  "source": "file:///my-playlist.m3u"
}

A line-in device in the studio:

{
  "type": "audio",
  "source": "line:///2"
}