---
title: Emergency override to an announcement
url: https://doc2.pstreamer.tv/en/manual/streamer/override.html
lang: en
product: Perfect Streamer
version: 2.0.2.423
---

# Emergency override to an announcement

> **Important**
>
> **Beta version 2.1.** What is described here exists only in beta version 2.1: it is installed from the beta repository and only with a licence; the stable version 2.0.2 and the demo edition do not have it. The beta version comes without warranty, and support is best effort ([Beta testing programme](../extras/beta.md#extras-beta)).

Since version 2.1.0.475 a single action switches the channels of a node — all or selected ones — to a programme with an announcement: an evacuation announcement, a fire warning or a hotel message. A second action returns the channels to their own sources. The Admin role starts and ends the override; all roles see that the override is on.

> **Important**
>
> Since version 2.1.1.501, the emergency override is available only while the “Emergency alerting” master switch is on ([Emergency alerting](../webui/administration.md#webui-emergency)); it is off by default. Before, the override was always available. So after updating a node where the override is used — including by scripts through the HTTP API — turn the switch on (the `emergency` key of the `server` section with the value `true`). While it is off, the emergency override HTTP API (`/data/override`) answers 404, and switching it off during an override ends the override.

## Key points

- **It lasts until a restart.** The override is not saved in the settings or on disk: after the streamer restarts, the channels work as usual and the override is off. If the announcement is still needed after a restart, start the override again.
- **All of a channel’s outputs follow it:** multicast/UDP, OTT, DVR and the programmes of MPTS multiplexers. The outputs do not need to be switched separately.
- **The operator chooses the channels.** The targets are either all eligible streams of the node or only those ticked when the override is started.
- **This node only.** The override affects the streams of one node. In a Meshwork domain, start it on each node whose channels must be switched.

## Announcement source

The source is a programme of an MPTS stream on this node. Prepare it in advance, before the announcement is needed:

1. Create an SPTS stream that plays a video file with the announcement in a loop ([Files and devices](other_io.md#streamer-other-io-file)), or a stream that receives the announcement from an external encoder.
2. Feed it into the MPTS stream through a multiplexer output ([Assembling the multiplex](mux.md#streamer-mux-setup)). The programme number (PNR) of this stream in the multiplex is what you choose when starting the override.
3. Check that the MPTS stream is running and that the programme is in it.

> **Warning**
>
> In version 2.1.0.475, do not feed the announcement file straight into the input of an MPTS stream: such a stream uses up memory and can stop the node. The file is played by an SPTS stream, and a multiplexer output feeds it into the MPTS stream, as in the steps above. Since version 2.1.0.476 an MPTS stream reads a file at the pace of its PCR if the file’s first programme has a PCR ([Files and devices](other_io.md#streamer-other-io-file)); the scheme with an SPTS stream and a multiplexer always works.

One MPTS stream can hold several programmes — for example, announcements in different languages — and you choose the one you need when starting the override.

## Alert clips

Since version 2.1.1.505, instead of a programme of an MPTS stream the override can show an alert clip: an MPEG-TS file that each target stream plays in a loop. No SPTS stream or multiplexer needs to be prepared for this, and the target can be any SPTS stream of the node.

- **A clip per category.** Each of the 12 CAP alert categories (fire, meteorological, geophysical and others) can be given its own clip, and the default clip applies to categories without one. An override by category shows its clip, or the default clip if it has none. Clips are assigned on the “Emergency alerting” screen ([Emergency alerting](../webui/administration.md#webui-emergency)).
- **Where the clips are.** In the node’s clip folder, `/opt/pss/config/alert-clips/` by default. Clips uploaded in the console are in it in the `upload` set; each installed clip package is a set of its own.
- **Clip package.** The optional `pstreamer-alert-clips` package (deb and rpm, for streamer 2.1.1 and later; not in the demo edition) installs ready-made clips for all categories and a default clip. The package’s clips have two audio tracks, AAC and MP2. On installation the package assigns its clips only to categories that have no clip yet and never changes the operator’s choice; when the package is removed, the categories with its clips are cleared. The package does not turn emergency alerting on: the master switch is turned on separately.
- **Upload limits:** up to 64 MB per clip, all uploads together up to 2 GB and up to 1000 files; the node checks that the file is MPEG-TS.
- **If the file is missing.** A clip assigned to a category but missing on the node stays assigned, and an override by that category is refused until the file is back or another clip is chosen.

For automation through the HTTP API, the override accepts a category or a clip name instead of a source ([Managing the node over the HTTP API](../extras/api.md#extras-api)).

## Which streams are switched

“All eligible” means all SPTS streams of the node except:

- paused streams;
- the source MPTS stream itself;
- streams that feed programmes into this MPTS stream, including the SPTS stream with the announcement. Such a stream always stays on its own input; if you tick it explicitly, the console shows it among the streams not switched.

Only SPTS streams are switched.

## How the switch proceeds

- Each target stream moves to the announcement programme at once, without waiting for the timeout and the input check. The node switches about 20 streams per second: 100 channels in about 5 seconds. The outputs follow the stream in the same way as on an ordinary input change.
- A stream that could not be switched at once is retried by the node; after five failed attempts the stream stays on its own source, and the console shows it with the reason.
- **If the announcement is lost** — the MPTS stream has stopped or the programme carries no data — each channel returns to its own inputs after its “Stream timeout (s)” ([Source redundancy](spts.md#streamer-spts-reservation)). The channels are not left without a picture.
- Editing the inputs of a target stream during the override does not remove the override from it. Restoring the settings from a backup removes the override from the streams; start it again if it is still needed.
- **Ending** returns each target stream to its first input.

While the override is on, the node holds an alert with code 80 (`emergency-override`, [Emergency override](../extras/alert_codes.md#extras-alert-codes-override)): who started it, the source, the programme, the number of streams and the note. The alert clears when all streams are back on their own inputs.

> **Warning**
>
> If a stream could not be given back when the override ended, it keeps showing the announcement until the streamer restarts, and alert 80 does not clear. Restart the streamer to return such streams to their inputs.

## In the web interface

**Starting (Admin role).** The “Emergency override” button in the top bar is visible on every screen while the override is off. It opens a window:

- “What plays” (since version 2.1.1.505, if the node has clips) — “Clip by category” (a “Category” is chosen; next to it you see the clip that will be shown, or “no clip”), “Clip” (the clip itself is chosen) or “Stream” — a programme of an MPTS stream, as before (Alert clips). A category without a clip or a clip without a file cannot be chosen: the window names the reason;
- “Source (MPTS stream)” and “Programme” (for “Stream”) — the programme is chosen from the stream’s list of programmes or set in the “Programme number (PNR)” field (from 1 to 65535);
- “Targets” — “All eligible” (the window shows how many there are now) or “Chosen streams” with the “Filter streams” field, at most 10 000;
- “Note” — up to 200 characters, for example “evacuation”: it is shown in the banner and in the alert.

![The emergency override start window: “What plays” — “Clip by category”.](../../_images/webui_emergency_start.en.png)

The “Next” button fixes the choice and shows the “Start the emergency override?” confirmation with the number of streams and a warning about the outputs; the “Start override” button starts it. While an override is on or still ending, a new one cannot be started: end the current one first or wait until it is off.

**Banner (all roles).** While the override is on, an “EMERGENCY OVERRIDE” banner stands below the top bar on every screen: the state and the counter of switched streams, how many streams are showing the announcement right now (“… playing the announcement now”), the source and the programme, who started it and when, the note and the streams not switched, with the reason; a stream that ran out of attempts is marked “given up”.

**Ending (Admin role).** The “End override” button in the banner, after the “End the emergency override?” confirmation. While ending, the banner counts the streams given back and disappears when all are back. If some streams could not be given back, the banner stays after the end as well, with the “could not be given back” list, until the streamer is restarted.

**The stream during the override.** In the stream details and in the statistics, the input that carries the announcement is marked “emergency announcement”. This input cannot be moved, paused or edited; the stream’s own inputs keep their numbers.

The same — starting, the state and ending — is gathered on the “Emergency alerting” screen of the “Administration” group ([Emergency alerting](../webui/administration.md#webui-emergency)).

For automation — for example, on a signal from a fire alarm system — the same is available through the HTTP API ([Managing the node over the HTTP API](../extras/api.md#extras-api)).