Getting prayer times onto your TVs#

What you need

Time: 45 minutes for the first TV, 15 for each one after

• OpenMasjidOS installed, with OpenMasjid Display added.
• A TV with an HDMI socket.
• A decoder box, one per TV.
• A network cable to the TV, or good Wi-Fi there.

How this works#

One masjid computer works out the prayer times and produces a video picture for each screen. It sends that picture over your own network. At each TV, a small box receives it and puts it out over HDMI.

With a decoder box there is no computer behind each TV, and no cable running from the office to the prayer hall. The two beta options at the end of this guide do put a device at the TV, and give you something else in exchange.

Three kinds of screen#

There are three ways to put a timetable on a TV. Read this before you buy anything.

	Decoder box	Browser screen	Raspberry Pi screen
What it is	A small box that plays a video stream	A link you open in a browser	A Pi running our own screen software
At the TV you need	The box	A smart TV or a spare computer	A Raspberry Pi 4 or newer
Shows a timetable	Yes	Yes	Yes
Shows a camera or HDMI	Yes	Not advised — see below	Yes
Network it uses	About 1.5 Mbit/s, all the time	Almost none for a timetable	Almost none for a timetable
Status	The tested path. Start here.	Beta	Beta

The rest of this guide sets up a decoder box, because that is the path a masjid has run for a season. The other two are at the end.

What a decoder box is#

A decoder box is a small device, usually the size of a deck of cards. It takes a video stream from a network and plays it out of an HDMI socket. They are sold as RTSP decoders, IP video decoders, or network video receivers.

What to look for when buying one#

We are not going to name a model. Nobody has told us which boxes this masjid has actually run for a year. Recommending untested hardware, bought with a masjid’s own money, is not something this guide will do.

So here is what the box must do, which is enough to shop with:

Requirement	Why
Plays RTSP streams	This is what Display produces. A box that only does HDMI or USB is no use.
1080p output	Prayer times need to be readable across a hall.
Wired network, not only Wi-Fi	A prayer-hall TV should not depend on Wi-Fi reaching a far corner.
Starts playing on power-up, with no remote	After a power cut the screen must come back by itself.
Remembers its stream address	So nobody re-types it every time.

Step 1 — Make the screen in Display#

Step 2 — Wire up the TV#

Step 3 — Point the box at the screen#

Every box has a slightly different settings page, reached either on the TV with its remote or from a browser on your network.

Step 4 — Prove it survives a power cut#

Cameras and a laptop on the same screens#

Once the first screen works, the same wiring carries more than a timetable.

A camera. Add it under Sources in Display with its own network address, and any screen can show it. This is what puts the imam on a screen in the overflow room or the women's section.

A laptop or a recording. You need an HDMI-to-network encoder, which is the opposite of a decoder: it takes an HDMI cable in and puts a network stream out. Add that stream under Sources like a camera.

A screen that is a web page (beta)#

A screen can be a link you open in any browser: a smart TV, or a spare computer beside the TV. The page draws the timetable itself, so almost nothing travels over the network after it loads.

It works over the internet. The link rides your OpenMasjidOS remote access, so a screen in another building needs nothing extra. See Remote access.

It warns you the same way. The page dims itself and shows a red bar if it loses contact with the masjid computer. It waits about ten minutes before doing so, while the Screens tab in Display marks it offline within a minute. The dashboard notices first.

A Raspberry Pi driving one TV (beta)#

A Raspberry Pi plugged into a television, showing the timetable and playing cameras by itself. One command sets it up.

Why it exists#

Every other screen is sent video by the masjid computer. A Pi is on the same network as your cameras, so it opens a camera directly. The camera picture never passes through the masjid computer at all.

That is the reason to choose one. A browser screen cannot show a camera, and a decoder box gets its camera picture relayed through the masjid computer. A Pi does neither.

What you need#

Item	Why
A Raspberry Pi 4 or newer	A Pi 3 is refused by the installer. See the caution below.
Raspberry Pi OS Lite	The version with no desktop. The Pi draws to the screen directly, so it needs no browser.
2 GB of memory	Enough as guidance. Nothing measures it, and a Pi 5 is not needed.
The Pi on the same network as your cameras	Not an efficiency choice. A Pi that cannot reach a camera directly cannot show it at all.

Setting one up#

What you can do to it afterwards#

From the dashboard, for each Pi screen:

Action	What it is for
Watch what it is showing	A small picture of what the television is being sent, refreshed about once a second.
Turn the television off	On demand, or on a schedule each night. Off by default.
Force a resolution	For a television that negotiates a bad one.
Reboot	On by default, nightly at 3am.
Join Wi-Fi, set the timezone, update	Without going to the Pi.
Open a terminal	A root shell on the Pi. Read the warning below.

Adding the rest of the building#

For each new TV: add a screen in Display, copy its link, wire up a box, paste the link. The masjid computer does not change, and you do not pay anybody per screen.

Checkpoint

One TV shows the prayer timetable, and the Screens tab does not say Offline. The picture comes back on its own after you unplug the box and plug it back in.

If something goes wrong

What you see	Why	What to do
The TV shows no signal.	Wrong HDMI input, or the box has no power.	Cycle the TV’s inputs. Check the box has a light on it.
The box is on but the picture is black.	The stream address is wrong, or the box cannot reach the network.	Paste the link again from the Screens tab, exactly. Check the network cable at the box.
The screen says Offline in Display.	Nothing is playing that stream.	The box is not connected. Check its network cable and its stream address.
The picture stutters or breaks up.	Not enough network for the video, or a weak box.	Lower Picture quality on the source. Use a wired connection. Then try one screen on its own to see whether the box is the limit.
The TV is blank after a power cut.	The box does not auto-play.	Turn on auto-start in its settings. If it has none, that model is unsuitable — this is why you test one first.
The picture is sideways.	Orientation on the timetable does not match how the TV is hung.	Set Orientation on the timetable in Display, not on the TV.