What is a MUX and why does it matter?

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Telecommunication towerMUX. It is one of those words that gets thrown around a lot in the IPTV world, but what exactly are MUXes and how do they work? Our aim with this post is to clear up some misconceptions and help ensure end users get the TV channels they want and need, using the right number of MUXes.

MUX is short for Multiplex, which is technology that allows a broadcaster to compress or ‘zip’ TV content so that several channels can be distributed using the same bandwidth that used to be required for a single analogue channel.

Widescreen high definition TV screen with video gallery. Remote control in hand

MUXes allow broadcasters to deliver far more channels, giving consumers a vast array of choices.

For example, one of the BBC’s muxes, PSB-1, contains six different TV channels and over 10 radio stations all in the same space that used to be occupied by just BBC1 analogue.

Compared with the old fashioned analogue TV channels, these new digital, channels deliver better picture quality as well as features such as programme guides, multiple language tracks and interactive menus. Because they use less bandwidth broadcasters have been able to launch additional channels such as BBC3, E4, ITV2, creating more choice for consumers.

MUXes come into play for AV and IT professionals when they are specifying how many a particular project or client needs for their IPTV system. This really depends on which channels they want. Think of a MUX as a collection of channels which are set by the broadcaster, such as the BBC or ITV. It is key to remember that you cannot choose which channels make up a MUX. Let’s say a client wants to receive BBC1, BBC2, ITV, Channel 4, Sky News, BBC News and BBC Parliament. A very common set of channels for corporates. Now how many MUXes will they need?

BBC1, BBC2, BBC News and Parliament are all on the same MUX (PSB-1), along with BBC radio stations and BBC3 and BBC4. The same goes for ITV and Channel 4 – they are all delivered through the same MUX (PSB-2) along with Channel 5, Film4, E4, etc.  Unfortunately, Sky News pretty much requires an entire MUX for just itself because the other channels alongside it are mainly shopping or entertainment channels. So, in this instance, you will need three Freeview MUXes to deliver the channels requested by the end user.

The selected MUXes are then “deMUXed” by the TV server, allowing you to choose just the channels you want from each MUX, before they are broadcasted onto the local IP network and onto the screens, desktops and other devices.

It’s important to understand that the channels that make up the MUXes are not set in stone. Broadcasters can and do change their MUX groupings from time to time. This is why it’s a good idea to have a spare MUX input if possible. (This could be used for non-essential but nice-to-have channels until a time comes when the spare input is needed for business-critical channels.)

Now, with an understanding of how MUXes work, let’s compare Freeview to Freesat.

Freeview delivers TV via eight MUXes, while Freesat uses over 50. This is because Freeview delivers only the channels which are relevant in any given location, while Freesat delivers all channels everywhere. As a result, each Freesat MUX tends to contain only one or two channels that an end user actually wants (along with a multitude of channels they probably don’t want, such as religious, cooking and shopping channels, and channels for other regions). With Freeview, on the other hand, the more desirable channels tend to be compressed into single MUXes without being as ‘watered down’ by unwanted regional and other channels.

old fashioned analogue tv

Now five HD channels take up the same ‘space’ as one old fashioned analogue channel.

Thus, Freeview allows you to deliver more channels using fewer MUXes, making it the more cost effective option unless there’s an unrelated reason why you have to use Freesat – for example, if you can’t install a TV aerial on the roof because the building is blocked by other larger buildings, or you need a specialist channel such as Bloomberg or CNBC which is only available on Freesat.

The take-away message for AV and IT professionals is that it is never possible to choose a ‘pick and mix’ option with channels. Even if the end user only wants one channel from a MUX, this will still need an entire MUX input. On the other hand, if you want 10 channels that happen to be on the same MUX, this only requires one MUX as well. In general, four Freeview MUXes are usually enough to provide the most popular TV channels, including the major BBC, ITV and 24-hour news channels.

We hope this information has been useful. If you have any questions or comments, we’d love to hear from you. Email jamie.cunningham@encodedmedia.com or click on the chat button on the left side of the screen.