The HDMI connector is the modern standard interface for connecting your audio-visual devices together.
However, many people are confused by this connection type, so here I will look at some common issues and explain them in more detail.
When should you use HDMI? What video and audio formats are supported? Which cable type do you need?
All this, and more, is explained.
Everything you wanted to know about HDMI but were too afraid to ask…
The HDMI connector on the back of your TV or Blu-ray player looks like this.
It's a bit like a
USB port on your computer - but a bit taller and wider. Er, and it's not a
rectangle. OK, so it's nothing like a USB port on your computer!
The connection is designed so that HDMI cables will only fit one way around.
The examples in the picture are HDMI inputs on the back of an AV receiver. It is usual for a receiver to have several HDMI inputs. This is where you connect the HDMI outputs from your devices.
Even though the input is labeled with a device name - it doesn't matter what device you connect to it. They are all the same. The names just provide a guide and can make it easier to remember where everything is connected.
You will also see this name on the receivers front display when you select that input. However, in many receivers, you can change this name and call it whatever you like.
The HDMI cable that is used to connect two devices looks like this.
You just need one cable between devices to transfer the sound and the picture.
The HDMI connectors are often silver, although some brands come with gold-plated HDMI connectors.
The color or material of the connector won't make any noticeable difference in performance.
HDMI cables transmit digital video and digital audio signals between devices.
They support standard-definition, high-definition and Ultra HD video signals - plus all uncompressed and compressed stereo and surround sound audio formats.
Any device with HDMI must support the minimum standard of uncompressed stereo LPCM audio.
Any other formats are optional – so the actual audio types available to you will be limited by the hardware that you are using.
The HDMI specification allows for 8-channels of compressed and uncompressed audio at 1-bit, 16-bit, 20-bit and 24-bit – at sample rates of 32kHz, 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz, 176.4 kHz and 192 kHz.
In practice, that means that you will have access to all of the common modern audio formats.
HDMI supports all the common stereo and multichannel audio formats for modern TV, movie and music content:
Many other audio formats such as FLAC, ALAC, and WAV will also be available if supported by your hardware.
If you need something specific, then you should check the documentation for that device. It won’t be HDMI that is limiting you, it will be the design of your device.
All HDMI cable types will support the transfer of all audio formats within the specification.
If you are unsure, my guide to surround sound formats explains all about Dolby and DTS audio.
As the HDMI specification is updated more video formats are supported. Your hardware will need to support that HDMI standard to use that video resolution.
Remember, manufacturers may still limit some video formats on their devices. They may also add support for a format that isn’t in the HDMI specification - as long as it is within the bandwidth limits of that version.
Always check the manual for your device to see what it can do.
Generally, this is the best connection to use to link most modern audiovisual devices together... assuming each device has an HDMI port of course!
Most devices made in the last couple of years will probably have these, older devices may not. Remember, the HDMI connection sends the video and the audio signals, and so one cable is all that is required.
There may be some situations where you can't just use HDMI to connect all your devices. For example, you may have HDMI on one device and a DVI connector on another.
In this situation, then it is possible to buy DVI to HDMI adapters (pictured below) to change one end of a cable from one connector type to another.
Therefore, you can use a normal HDMI cable, but put the adapter on one end of it and plug the adapter into the DVI connection. Bingo!
Remember, if you use an adapter like this then you will only be able to transmit the picture as, unlike HDMI, DVI only supports video signals.
The DVI device may also need to be HDCP-enabled to send certain signals like encrypted Blu-ray movies. All HDMI devices support HDCP.
When you are looking to buy a new cable, there are a seemingly endless number of variations to choose from. It can seem impossible to choose the best HDMI cable.
There are different colors, different lengths, different materials, different specifications and different prices.
It can make your head spin.
Fortunately, it's not too difficult once you just concentrate on the important stuff. Think about these points to find the best HDMI cable for you:
Oh, you want more of an explanation?
The theory is that a gold-plated connector will be more resistant to oxidization and will conduct the signal better. The truth is you are hardly likely to get much oxidization going on in your living room.
Or is your HDTV in the garden?
Anyhow, there is such a small amount of gold in the gold-plating that it won't make much difference anyway.
Still, it looks nice and shiny.
By all means, buy an HDMI cable with gold-plated connectors, but I really wouldn't pay extra just for this feature.
HDMI allows the transmission of all video signal types - including high-definition signals up to Ultra HD 4K/60p. Plus, up to 8 channels of uncompressed digital audio - such as Dolby TrueHD and DTS-HD Master Audio.
There have been different versions of the HDMI specification over the last few years. The most widespread versions are HDMI v.1.4, and the newer HDMI 2.1.
The new HDMI 2.1 specification supports video resolutions up to 4K/120p and 8K/60p. Plus, the object-based audio formats of Dolby Atmos and DTS:X.
The older versions have some limitations for the features they support. Therefore, the HDMI inputs and outputs on older devices may not have the same functionality as newer ones.
ARC stands for Audio Return Channel.
Introduced in the HDMI 1.4 specification, an HDMI ARC connection allows a device to send data in two directions. Video and audio from the source device – and audio back to the source.
The main point is to reduce the number of cables that are required between devices.
In a standard HDMI connection, you send data from a playback device to a display device. For example, you connect a Blu-ray player to a TV using an HDMI cable - and the Blu-ray player sends the picture and audio to the TV.
With an ARC connection, the TV can send audio back down the same HDMI cable to the Blu-ray player.
So, what's the point of that, I hear you cry?
Well, in that case, there is no point, as the Blu-ray player doesn't play audio.
However, what if that HDMI connection was between an AV receiver – or a soundbar system?
This is where an ARC connection is useful. The AV receiver can send video to the TV to display – but it can also receive audio from the TV to play over the speaker system.
This is useful as the TV might have in-built apps like Netflix or Amazon Prime Video. It is then easy to play the audio from these apps on your home theater speaker system. All using the same cable.
Many soundbars are now using HDMI ARC to send audio from the TV to the soundbar. Previously these connections were often made using an optical cable.
HDMI ARC supports PCM, Dolby Digital and DTS signals – both stereo and 5.1. It also supports Dolby Digital Plus.
HDMI eARC connection is an improved version of HDMI ARC. It was introduced in the HDMI 2.1 specification.
What is the main difference between HDMI ARC and eARC?
eARC allows for the transfer of higher-resolution audio – namely Dolby TrueHD, DTS-HD Master Audio, Dolby Atmos and DTS:X.
You will need an 'HDMI cable with Ethernet' if you want to use an eARC connection.
If you want to send audio from your TV to an AV receiver or soundbar you will often have a choice of two options – HDMI ARC or a digital optical output.
So, which is best?
I wouldn't say either is 'better' than the other.
Does the same audio signal sound different over HDMI ARC and optical? No. Although, as always, you will find some swear blind that they do.
However, your circumstances may determine that one is better for your system than the other.
Make the decision depending on your hardware and what makes sense for your system. In many systems, you might not have a choice.
You will just use the connection type supported by all your hardware.
If I have the choice of using either, I will usually use HDMI ARC. As, if nothing else, it saves me connecting another cable.
CEC stands for Consumer Electronics Control.
CEC was introduced in HDMI version 1.2 and allows for devices to control each other via an HDMI connection.
For example, when you switch on your TV, CEC will automatically turn on your soundbar.
Or, your Blu-ray player will automatically select the correct HDMI input on your TV.
You will need to enable CEC in the settings menu of each device that you want to use this with.
CEC is called different things by hardware manufacturers. For example:
You may find some devices, especially from different brands, might have trouble talking to each other successfully.
Also, it can sometimes be annoying as a device will switch itself on/off when you don't want it to.
However, when it is set up correctly it can prove a useful feature and mean you need to use fewer remote controls.
Be careful when you are buying an HDMI cable. Some brands like to make out that their cable is faster than the rest and use many exciting ways to describe them.
There are currently only 3 official specifications for the speed of an HDMI cable:
Categories 1 and 2 have two different types of cable - an ordinary cable and one 'with Ethernet'.
Internally, HDMI cables have 4 shielded twisted pairs and 7 separate wires. The 'with Ethernet' versions use two of the 7 separate wires to create an extra twisted pair conductor.
A Category 3 HDMI cable includes the Ethernet wiring as standard.
A 'standard speed' category 1 cable has been tested at speeds of 75 MHz.
An HDMI cable has 3 data pairs of wire that transmit the signal. The two different categories of HDMI cable are speed tested using just one data pair.
Yet the bit-rate you see quoted will often be the combined total for all three (to get a higher number to impress you with).
This means a 'standard speed' category 1 cable has been tested to transfer data at 742 Mb per second for a single data pair. Or, 2.2 Gb per second for the three combined.
This is the equivalent of a 720p or 1080i video signal.
A 'high speed' cable that has been tested at speeds of 340 MHz. This is up to 3.4 Gb per second for each data pair of wires - or a maximum of 10.2 Gb per second for the three pairs combined.
This is the equivalent of a 1080p signal at 60 frames per second - or a 4K 2160p signal at 30 frames per second. This would also include 3D video and any signals with increased color depth.
There is a new certification for a 'Premium High-Speed HDMI Cable'. This is a category 2 cable that has been tested up to the theoretical maximum of 18 Gb per second - and should support any video up to 2160p/60Hz, BT.2020 and HDR.
However, in reality, any ‘high speed’ HDMI cable will probably work fine.
An Ultra High Speed HDMI Cable that has been tested at data transfer rates up to 48 Gb/s.
This new category was introduced to allow for the increased speed requirements of the HDMI 2.1 specification.
This includes video resolutions of 4K and 8K at 120 frames per second.
The full range of video resolutions and frame rates supported by HDMI 2.1 and an Ultra High Speed Cable are:
It will also handle the high-resolution audio formats required for eARC – Dolby TrueHD, DTS-HD Master Audio, Dolby Atmos and DTS:X.
However these audio formats are supported by any HDMI cable - so you don't need to buy one of these cables just for high-resolution audio.
This cable will work with any of the older HDMI connection types.
Compared to an ordinary HDMI cable, an HDMI with Ethernet cable has an extra twisted pair of wires inside.
Category 1 and 2 cables come in two types. Standard ones and those ‘with Ethernet’.
Category 3 cables come with the Ethernet wiring as standard.
HDMI eARC connections require a cable ‘with Ethernet’.
No. The versions of HDMI before 1.3 fully supported the transfer of HD audio.
However, this required the HD audio to be decoded by the playback device and then sent across the cable to the amplifier as a Linear PCM signal (LPCM).
The amplifier/receiver also needed to support HDMI audio (not all did).
What was added by HDMI 1.3 was the ability to bitstream the HD audio to the amplifier/receiver.
This means the HD audio signal is sent ('streamed') directly to the amplifier/receiver without being decoded first. The decoding is done by the receiver instead.
For this to work, all of the parts of the chain must be HDMI 1.3 compliant.
Cables aren’t defined by the version numbers of the HDMI specification i.e. 1.2 or 2.0.
These numbers refer to the capabilities of the HDMI circuit boards inside your devices.
So, an HDMI 2.0 cable doesn't exist.
There are currently 3 standards of HDMI cable - category 1 (standard), category 2 (high-speed and premium high-speed) and category 3 (ultra high-speed).
The different standards of HDMI cable are simply designed and tested to transfer a maximum amount of data. It is increased video resolutions that have required the improved data rates in newer HDMI cables.
To transfer 4K Ultra HD video, 1080p video and 3D TV signals you should make sure you buy a category 2 'high speed' cable.
This will ensure it will transfer the high data rates required. If you aren't sending the higher resolution signals, then a standard category 1 cable should be sufficient.
You might need a Category 3 Ultra High Speed HDMI Cable if you want to run 4K/8K video at high frame rates.
Probably not. If you already have a 'high speed' category 2 HDMI cable, then this will support all the requirements of HDMI 1.4 and 3DTV signals (with one exception - see below).
A standard category 1 cable hasn't been tested to support the higher data rates, and so may not be reliable enough. However, before you buy a new cable, give it a try and you may find it will work.
One part of the new HDMI 1.4 specification will require a new cable. The 1.4 update supports an Ethernet connection through HDMI. To utilize this in your equipment, you will need a category 1 or 2 HDMI cable 'with Ethernet'.
Only if you currently have a category 1 HDMI cable. A category 2 ‘high speed’ HDMI cable will support up to 4K/60 UHD video.
Although only ‘Premium High-Speed HDMI cables’ are tested up to the required limit, any category 2 cable should be fine.
Try your existing cables first, and if you have a problem, you can buy new ones.
The cables pictured below are certified Premium High-Speed HDMI cables:
Maybe, but probably not. An interesting point has been reached where the maximum data rate specification of the HDMI 2.0 specification has overtaken that of the 'fastest' HDMI cable.
HDMI 2.0 devices are designed to transfer data up to 18 Gb per second, whereas a 'high speed' category 2 cable is only designed to support a maximum of 10.2 Gb per second.
However, a well-made category 2 cable will probably handle data rates far higher than it has been tested to.
To be sure, the HDMI licensing authority has introduced an optional 'Premium HDMI Cable' certification, which is allowed to be used on category 2 cables which have been tested up to 18 Gb per second.
The same rule applies to that mentioned above. Try the cable you have already, and if you get picture drop-outs or interference, then maybe consider getting a 'Premium HDMI Cable'.
Maybe. HDMI 2.1 allows for increased video resolutions of 4K/120p and 8K/60p.
If you are trying to use any of these new video resolutions, then you may need to buy a new Ultra High Speed HDMI cable:
If you are using HDMI 2.1, but not trying to transfer these new video formats, then an older Category 2 cable should be fine.
First, try your old cables, they may work. If you have a problem, then you might need to invest in new cables.
The length of your cables will be important. If your cables are 2 or 3 meters, you might not have a problem with an older cable.
For longer distances, then the cable specification becomes more important.
Ultra High Speed HDMI cables are a new cable type released for the HDMI 2.1 specification. They are category 3 cables.
Initially called 48G cables, an Ultra High Speed HDMI cable supports data rates up to 48 Gbps.
The increased speed was required to support the new features of HDMI 2.1 – uncompressed 8K/60p, 4K/120p and high-resolution audio via eARC.
It is fully backward-compatible with older HDMI connections.
No. The circuitry in an HDMI 2.1 board uses the wiring inside an HDMI cable in a different way. So you would need a new HDMI board installed inside your device.
There is no defined maximum cable length for HDMI cables - only a required performance.
The ability of a cable to accurately reproduce signals over a long distance is very much dependent on the build quality of the cable. And, the quality of the circuits in the devices.
However, in practice, a high-quality cable should be able to transfer data successfully over about 10 meters. Then, a repeater or amplifier may be needed to boost the signal.
Over a short distance, like less than 3 meters, almost any cable should be able to transfer the required data.
Don't be fooled into buying over-priced HDMI cables if you only need short cable lengths.
Yes. HDMI is fully backward compatible with older versions.
There are five types of HDMI connector:
They are essentially the same, except HDMI has:
Yes - although not DVI-A. You can buy HDMI to DVI cables and send video signals between devices.
However, this will not send audio, and so you will need to make a separate connection for the sound.
HDMI cables are audio/video interconnects that send digital signals between AV devices. Component video cables send component analog signals between devices and are restricted to video only - they do not send audio signals.
Yes, you can. One way is to use your AV receiver. Many AV receivers can upconvert a component input to an HDMI output.
However, you will need to check the manual for the AV receiver as not all of them will do this.
Another way is to use an adapter or converter. There are plenty to choose from. The Portta Component to HDMI Converter, pictured below, will do the job.
You just need to check that the converter you use will deliver the signal that you need. The one above supports resolutions up to 1080p.
Also, you need to be clear about what you want to convert from and to.
The converter above will only convert from component video (+ stereo audio) to HDMI i.e. sending a picture from an old games console to the HDMI input on a TV.
If you need to do something different, then you need to look for the correct converter for that job.
This is something that many people get wrong and end up buying the wrong device.
In some situations, you may find it difficult, or even impossible, to plug your HDMI cable into your device.
The most common scenario is where you have your flat screen TV mounted on a wall.
Unless the HDMI ports are on the side of the TV, there will often be no room between the back of the TV and the wall itself to plug in your cable. Oops.
Drum roll, please. Step forward, the life-saving right-angle HDMI adapter!
This useful little device will connect on the end of your existing HDMI cable and create a 90-degree connector.
Thus, allowing you to plug in the cable even in the tightest of areas.
You may also see these described as 270-degree HDMI adapters. It's the same thing really. It just means the HDMI connector is designed to point up - rather than down.
If this is important, just make sure you buy one that points the right way.
The adapters I have linked to above come with both versions. One that points down (90-degree adapter) - and another that points up (270-degree adapter).
Of course, this does depend on the orientation of the port on your device.
If you are really on-the-ball - and I don't doubt it for a minute - you can also buy HDMI cables with a right-angle connection already fitted on the end.
So, saving the added expense of buying adapters.
It's your lucky day, indeed you can.
If you have a device with an HDMI output, like a laptop, for example, you may need to connect it to a projector that only has a VGA input.
On the face of it, you're a little bit stuck.
However, thanks to the wonders of modern science, there's a fairly easy solution to the problem.
There are a number of HDMI to VGA converters available that will suck in the HDMI signal and spit it out disguised as VGA.
Did I mention I'm not too technical?
All you need to do is plug the HDMI connector into the HDMI output of your laptop - or whatever device you need to send the signal from.
Then, connect the VGA to your display device. Be that a projector, computer monitor or TV.
The model above supports resolutions up to 1920x1080 at 60Hz. It also comes with an external power supply which you might need if you are connecting to a device that doesn't output enough power.
Yes, it can. You will need to buy an adapter that supports the device you are using.
Why might you want to do this? The most common reason would be that you want to connect your computer or notebook to an external monitor or HDTV.
You will then be able to send video and audio into an HDMI port on your display device.
If your device already has an HDMI output, then you should just use that.
However, if you don't have an HDMI output then you will be able to send video and audio to another screen using a USB adapter.
You could also use this type of adapter to add a second monitor if you are already using an HDMI output.
This USB to HDMI adapter will convert a standard-size USB 3.0/2.0 connection to 1080p video and HD audio.
However, this model will only work on a device that is running a Windows OS – XP, 7, 8, or 10. And, it also only supports 1080p video on a USB 3.0 port.
So, you must read the description of the adapter before buying one. Many will only support certain operating systems, video resolutions, and audio formats.
If you want a USB converter that works with a Mac device – like a MacBook or iMac – then you can buy something like this QGeeM USB C to HDMI Adapter:
This converter uses the smaller USB type-C connection. So this can be used with devices that don't have standard USB ports available.
You can also use this converter on devices such as a Surface Book, Samsung Galaxy phone, Chromebook, or Pixelbook. Anything which uses a USB Type-C connection.
It also Thunderbolt 3 compatible.
The main thing to be aware of is that USB to HDMI converters are often specific to different devices types. Make sure that you buy the right one for the device that you have.
Paul started the Home Cinema Guide to help less-experienced users get the most out of today's audio-visual technology. He has worked as a sound, lighting and audio-visual engineer for around 20 years. At home, he has spent more time than is probably healthy installing, configuring, testing, de-rigging, fixing, tweaking, re-installing again (and sometimes using) various pieces of hi-fi and home cinema equipment.