TV Inputs/ Outputs – How They Work & What They Do

If when you look behind your TV it leaves you confused, or whether you just want to know what all the different connections on your TV do. Read this blog for all you need to know, this includes information on all the different AV inputs and outputs on your TV which will hopefully leave you well informed to be able to correctly set up your TV. This blog is the perfect companion to out previous blog on different TV cables which I recommend that you check out when you’re done here. Let’s begin.

HDMI Input

The HDMI input in the most common input used in today's world. Into a HDMI input a HDMI cable in inserted that connects between your AV equipment and your TV. It can be used for both digital video & audio. Most TV’s purchased nowadays will typically have 4 HDMI inputs which can be used to connect Satellite RX’s, Sky boxes, Bluray players, Games consoles and so on all at the same time. The good thing about the HDMI connection is that it’s constantly being updated to be carry to carry more information for when future improvements in picture resolution (8K, 4K, High Definition). The HDMI cable is also capable of delivering 7.1 audio for surround sound systems. If you have a choice of different ways to connect your TV equipment, the HDMI connection is advised.

HDMI ARC Input/ Output

If you look at the rear of your TV HDMI connections, you may find one labelled ‘HDMI ARC’ which stands for High Definition Multimedia Interface (HDMI) Audio Return Channel. There are various functions which this input/ output can serve and the most common being an audio output connection to TV soundbars and inputs for AV receivers, surround sound systems.

SCART Input/ Output (Euroconnector)

The SCART connection is a big bulky horrible connection which is always falling out, far inferior to a HDMI connection but for a relatively long period of time it was the most common connection for connecting DVD Players,early satellite receivers etc. The word SCART is a French Abbreviation meaning ‘Syndicat des Constructeurs d'Appareils Radiorécepteurs et Téléviseurs’ and was very popular in Europe – not so much in places like the USA where it never really took off. The SCART connection is an analogue only connection making it not suitable for a digital TV picture and high definition.

The reason that the SCART connection is log big and heavy is that there are 21 pins with 21 individual cables inside of the lead all serving different purposes like RGB Video, S-Video, Stereo sound, automatic source selection and so on making it actually a very versatile connection. If you lose the TV picture but the sound works fine, or vice versa it’s likely that the SCART has wobbled loose at one side. You’re only likely to use the SCART Input/ Output for connections to old equipment and old TV’s, or when you have no HDMI inputs available.

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The SCART input is not ideal for use with wall mounted TV’s as to fit it behind the TV often means having to stand the TV a fair distance for the connector to fit. In situations like this,you may be better using the composite/ component connection instead. The SCART input is sometimes labelled as AV or where there is more than one SCART connection, AV1, AV2.

Ethernet/ RJ45 Input

A common connection on most new Smart TV’s is the Ethernet connection in which you can directly connect the TV to a wired internet connection for improved speed/ performance on Smart TV services and catch up TV for internet streaming and TV on demand. The Ethernet connection is also sometimes called the network connection, RJ45 or 8P8C.

A lot of early “non-smart” TV’s that are not compatible with Internet based services still have an RJ45 connection. You might be wondering what is the point in this? The primarily function in this situation would be to connect to you local internet connection to allow you access the TV interface for maintenance, like software updates. It’s highly unlikely that would ever need the Ethernet input in this instance.

Optical Input/ Output (Toslink)

The optical output is a very small connection, into which a small thin optical cable connects. The optical input/output is a digital audio only connection which is commonly used for external audio equipment like soundbars, AV receivers & amplifiers. You will notice that the optical connection has a beam of light going through it, this is because it is a fibre optic cable and the information is sent down at very high frequencies. The optical connection is capable of 5.1 surround sound, for 7.1 systems a HDMI connection is required.

Digital Coax Audio Input/ Output

The Digital Coax Audio connection is very similar to the Optical (Toslink) connecting in terms of performance, it supports 5.1 surround sound but the main difference is that the digital audio signals are sent down a coax conductor cable rather than a fibre connection. The Digital Coax can be used to connect to external sound equipment  soundbars, surround systems & AV receivers.

Auxiliary Input/ Output / Headphone Jack

The Auxiliary connection, sometimes shortened to ‘Aux’ or known as the Headphone jack is for connecting your TV to headphones or an external sound system, like a soundbar. It’s a single channel analogue audio cable so better sound quality can be achieved by installing a Toslink, Coax Audio or phono connection where possible. Some TV’s will automatically mute the TV speakers when a cable is inserted into the Aux input. I had a customer that didn’t want the TV to do this as they wanted to connect wireless headphones and keep the TV sound on at the same time, it wasn’t possible this would to do with the actual hardware of the TV and not the software, not all TV’s are the same though however.

USB Inputs

Most TV’s purchased now often have many USB inputs which can be used for various functions. It is most common to use the USB connection to insert a USB stick which will allow you to view media stored on it, like video and photos. Sometimes with compatible TV’s the USB connection will allow the TV to be connected to an external USB storage device like a USB stick or portable hard drive for PVR functions (recording services).The USB connection is sometimes used as a wireless adapter that allows TV’s TV’s to be connected to your WIFI network for internet streaming services. Overtime this has become less and less common as most new TV’s now have a WIFI facility built in meaning that the USB dongle is not required. Also, another function which is not commonly utilised now would be for software upgrades on TV’s, the required files can be downloaded from the internet and inserted into the TV – This speeds up things greatly when compared to Over The Air software updates which were done via a TV aerial or satellite dish and could take forever( I have been there!). This is no longer common as it is much easier for this to be done over the internet with compatible TV’s.

RF Input(s)

Perhaps the most common connection that is used is utilised on TV’s is the RF connection. RF stands for radio frequency and is most commonly a push in IEC coaxial aerial input. This would deliver Freeview in the UK and similar services like Soarview in Ireland.

Increasingly over time, more and more TV’s are also incorporating a separate screw in RF connection which is a satellite F connection for a direct connection to your satellite dish. It depends on the make/ model of your TV but sometimes this will be compatible with Freesat or not. If not, the TV will be a generic Free To Air type receiver and will store the TV channels on all sorts of odd numbers.

Composite Video Input

The composite video input, which is sometimes just referred to a AV on your TV source menu is a yellow phono connection. This is a analogue video only connection so not compatible with High Definition video connections and will require separate audio cables for sound, this is usually supplied by an RCA cable with separate red and white phonos for analogue stereo sound.

S-Video Input

S-Video stands for Super-video and it never really took off but it’s an improvement on the picture quality of component video. By separating and sending the luminance (Brightness) and Chrominance (colour) in two separate streams which gives an improvement picture quality. Like component video the S-Video connection is not compatible with audio so separate audio cables are required.

Component Video Input (RGB)

A component video input is a further improvement on composite video and S-Video connections. It works by sending the Red, Green & Blue (RGB) analogue colour streams down separate colour cables which gives a further improvement on picture quality. Again, like Component & S-Video separate audio cables are required. A downside of Component Video is that for one connection five separate phono cables are required, Red, Green & Blue phono’s for the video input/ output and another red & white cables for sound, you can buy these in a single cable however. It’s worth noting that a SCART Cable is compatible with RGB and stereo sound so it may be easier to use one of these if the TV is compatible.

Stereo Sound Input/ Output

Depending on what type of TV you have you may have more than one pair of red and white phono connections for sound only connections. It’s common to have red and white phono connections to accompany video only connections like composite, S-Video, DVI and Component connections but some TV’s will also have a pair of phonos for sound outputs for connections to external sound systems so you need to make sure that you’re connecting to leads into the right places, otherwise you could end up with a TV that you can watch but not hear.

DVI Input

DVI stands for Digital Video Interface which can be used to for a digital video only connection between AV equipment and TV’s. DVI was used as an early precursor to the HDMI connection but can still be used if you have run out of HDMI inputs on your TV, with a DVI – HDMI adapter plug a HDMI output can be used to connect a DVI input which can be very handy as it means that you may not need a special DVI cable. DVI is not compatible with some of the latest HD resolutions and does not supply sound, meaning separate audio cables will be required.

VGA Input/ Output

It’s not common but some TV’s also had a VGA connection on them which would most like to connect a PC to a TV screen. VGA stands for Video Graphics Array and is a video only connection. Overtime like many of the other video only types connection this has been superseded by HDMI. The VGA connection itself is a bulky head connection which pushes into position and has a couple of fixing screws either side which can be finger tightened to keep the connection firmly in place. The VGA input looks similar, but should not be confused with an RS-232 or DVI input.

RS-232 Input/ Output

You may notice a connection on the rear of your TV called an RS-232 connection which looks similar to a VGA type connection. The RS-232 is more of a professional type connection for installers which allows for advanced control of the TV, for instance setting a PC up to control the TV or integrating the TV into a Home Automation system.

Common Interface Input

This connection is of virtually no use in the UK but sometimes used in other countries where encryption is used. The Common Interface is for accessing encrypted TV services, which may be a subscription type service. Depending on the TV and service that wants to be accessed it can be used with DTT, cable and satellite applications. A Conditional Access Module(CAM) is inserted into the Common Interface input and a Smart Card inserted into the CAM.

Samsung One Connect

I have included this in here as it may be helpful to someone. Some models of Samsung TV’s have no AV inputs on the TV itself whatsoever, instead a separate box is provided with the TV in which all the TV tuners, HDMI’s, USB’s, Video & audio cables all connect. From here a single cable One connection cable connects between the TV and the One Connect box, some require a separate power cable to be connected to the TV but some of the later models it is all provided down the One Connect cable. This can be very helpful when installing the Samsung TV on the wall as there are far less cables to have to route for your installation. A word of warning however, some of the One Connect cables are not bidirectional meaning that one end has to connect to the TV and the other to the box. I found this out the hard way after chasing the cable into the wall and filling over with plaster only to find the cable needed to be installed the other way around!

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TV Ports & Connection Questions?

If you have any questions arising from this blog please feel free to POST THEM IN THE BLOG COMMENTS SECTION BELOW and I will get back to you as soon as I can. I appreciate your patience when leaving a questions as I will not answer as fast as you may like.

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Until next time,

Tom