The “no signal” image

When a channel's source goes quiet — an outage at the source, a programme gap at the operator, a restart — viewers normally see a stopped player or an error. With the “no signal” image, Castreon shows them your image instead, with silent sound, until the programme is back. The player keeps playing, and the programme comes back by itself.

Available from Castreon 1.2.0, on all plans.

Setup

1. Settings → “No signal” image → Upload an image: PNG or JPEG, 16:9 (for example 1920×1080), at most 8 MB. The first image you upload becomes the default one.
2. Check that Show the image when the source goes quiet is on.
3. Appears after (seconds) — how long the source must stay quiet, beyond one segment's duration (2–60 s, 4 by default).
4. Save. The settings take effect at each channel's next start — or press Restart on the channels you want right away.

Without an uploaded image, nothing changes: channels work exactly as before.

Several images

Under Uploaded images you can keep several images and choose the default one with Make default. An image that is in use can't be deleted — remove it from the settings first.

Under Per channel → Add channel you can give a channel another image, or no image at all. Without a rule, a channel gets the default image.

A good image stays readable on a TV: large text away from the edges (keep about 5 % free on every side), no thin lines, no channel name if the same image serves all channels. Viewers should understand three things: the break is temporary, nothing needs to be done on their side, the programme comes back by itself.

What viewers see

• After the threshold, the player switches to the image without stopping and without errors. The image comes with a silent sound track, so players that need sound keep going.
• When the source is back, the programme continues on its own after a few seconds.
• The HLS playlist stays continuous all the time, also when the channel's process restarts while the image is on air: players never get a 404.
• A channel that has never had a programme since it started (for example a camera that can't be reached) also gets the image: Castreon builds it from the channel's settings, or in 1920×1080, 25 frames per second for a channel without a transcoding profile. After the first good start, it remembers the real parameters for the next time.

What you see in the panel

• The channel's status shows no signal (in red) instead of “running”, everywhere: the channel list, the dashboard, the channel page and the active source. Underneath: for how long.
• On the dashboard the channel counts as down, under “Needs attention”, as critical — the viewers don't see the programme, even if the process is running and reconnecting to the source.
• The reconnections while the image is on air are not reported as an unstable channel.
• The channel page shows a note with the time the image appeared; the channel history records when it appeared and when it stopped.
• Notifications: “Channel down” is sent once, with “no signal”, and the recovery only when the programme is really back.
• Showing the image now in the settings lists the channels showing it right now.

Limits

• It works on the HLS output with TS segments, for TV channels with H.264 video and AAC sound.
• Not for radio channels, LL-HLS, DASH, HTTP-TS, or sources with CENC encryption.
• With AES-128 encrypted HLS, the image segments are not encrypted (they contain only your image); the programme is encrypted again when it comes back.