Audio tracks, languages and subtitles

Many sources (especially DVB) have several audio tracks in different languages and one or more subtitles. Castreon shows you exactly what it receives and what reaches the viewer.

What comes in and what goes out

Open the channel and go to the Tracks and clients tab:

• Incoming tracks — everything the source sends: video, audio, subtitles, data. For each one you see the Language (with its name, not just the code) and Details.
• The on air label shows what actually reaches the viewer.

By default, all audio tracks are passed on.

Choosing a track

Next to each track there are two buttons:

• by language — selects the track by its language (for example “audio in English”). The recommended option: it survives switching to the backup source, even if the backup has its tracks in a different order.
• use — selects exactly that track, by position.

The panel asks for confirmation (Change and restart), then the channel restarts with the new selection — the picture stops for a few seconds for anyone watching at that moment.

Subtitles

The subtitle mode is set in the channel editor, under Subtitles:

If the source has subtitles but the channel is set to “no subtitles”, the channel page tells you and offers an Enable subtitles button. If the source has no subtitles at all, it says so explicitly: “The source has no subtitle tracks.”

Good to know about HLS

DVB subtitles come in two kinds: image (dvb_subtitle, the most common) and text (teletext). The HLS format cannot carry a copied DVB subtitle as is. To see it on HLS, choose burned into the image (the channel's profile must transcode). Copied as in source works on MPEG-TS outputs: HTTP-TS, UDP and SRT. If you enable copied subtitles and the channel only has HLS, the channel log warns you.

Audio in the profile

The audio codec, bitrate and number of channels (stereo or 5.1) are set in the transcoding profile — see Transcoding profiles.