AV Signal Conversion

AV Signal Conversion

CIE’s HowToAV.tv explains AV signal conversion...



With a wide variety of AV devices and AV formats being used for different commercial and residential applications, integrating various formats is a regular challenge for anyone trying to create the ideal media system for their professional or home system. In this blog, the HowToAV.tv team explains how you can connect together many of the most common audio and video formats to create a system that works as you want it to.

What Does AV Signal Conversion Mean?

An AV signal refers to the picture and sound which is created by a media source device such as a Blu Ray player, games console or Sky Box. These AV signals are distributed over an AV system, sending it to the output display, television or projector for viewing.

Many of the latest and most frequently used AV devices use the HDMI standard, but older devices and computers use different formats such as VGA or DVI, as well as distinct audio sources which are separate to the video signal.
There are different options available when you’re converting AV signals from one to another; from simple cable converters, through to specially designed devices which not only convert but also extend and amplify the signal as required.

What Is An ADC? (Converting Analogue Audio To Digital)

ADC stands for Analogue to Digital Converter, or conversely there is also DAC, which stands for Digital to Analogue Converter.

In AV applications ADC refers to the conversion of audio signals between analogue and digital. This is usually required when you add or replace devices, resulting in a mis-match of analogue and digital signals which are incompatible with each other. 

An example of this is audio amplifiers, which often create traditional analogue sound as it is considered better quality. Analogue signals are usually related to legacy and traditional music source devices such as record or tape players, whereas modern devices such as games consoles; MP3 player/iPods and Sky Boxes all create digital audio signals.

So if you are linking an older analogue audio signal to a modern device you are going to need an ADC converter, but if you are linking a digital sound to an analogue system, then you will need a DAC converter.

There are a variety of reasons you might need to use a DAC converter, one example being to employ an analogue hi-fi system to improve the audio performance from a digital media device such as a games console or Blu-Ray player.


How Do I Plug My Apple TV Into My Audio Amplifier?

Over the last few years there has been an increase in the use of internet based TV subscription services and devices such as Netflix which work by storing big libraries of shows and movies in an on-demand format, giving people more freedom to choose what and when they want to watch.

One of the most popular device/services is Apple TV of course, which is designed to link with your Apple account allowing you to buy, rent and watch any content on your TV which you have bought through iTunes on another connected device.

One issue however is the lack of connection ports on Apple TV, which can appear to leave you with limited options for the rest of your media system, something which might be a problem if you wanted to connect the device to your analogue hifi or sound reinforcement system.

Firstly Apple TV does contain an ‘Optical Audio’ output which uses a fibre optic cable directly from the Apple TV box to an amplifier. Some amplifiers are compatible with this output (the digital coax or Toslink), however many are not, which will mean the solution  to connect the two devices is by using a DAC (digital to analogue) converter.
This will allow you to input the digital audio signal from the Apple TV’s optical output and convert it to analogue audio via dual phonos, which can then easily be connected to your external hi-fi system.

If the distance you are sending the signal from your Apple TV to your display device is over the recommended 10m for the HDMI leads, then you will need to consider adding an HDMI repeater to prevent any loss in signal.

This is because the HDMI output of the Apple TV carries both video and audio signals. These can be connected to an HDMI repeater with de-embedding function, allowing you to increase the HDMI signal transmission distance, and de-embed the signal which separates the audio from the video allowing you to play it through an external audio system.


AV signal


Can I Embed A Different Audio Signal On To An HDMI Signal?

There are various reasons why you would want to overlay a separate audio source over an HDMI signal. This is often in commercial settings where music or other independent sounds want to be played whilst keeping a channel playing on the TV.

One example of this would be a waiting room inside a doctor’s surgery which has a news channel on the TV but with the radio playing through the speakers instead of the TV’s sound. Similarly a pub which wants to switch between the audio from a televised football match and another music source such as a live DJ would need to split the signal in order to switch between them.

The most effective option for this application is an HDMI inserter, which can embed separate audio sources into an HDMI signal that has been connected through the input. The inserter then distributes a combined signal through the device’s HDMI Out connection which can then be plugged into the screen/TV.

If you are trying to achieve the opposite of this and split the audio source from the HDMI signal to play it through a separate audio system, then you need an audio de-embedder. These are perfect for sending the audio from an HDMI signal to a separate speaker/PA system.

How Do I Convert A PC Signal To HDMI?

Computers and laptops bought within the last 5-6 years will probably come with a built in HDMI port which allows you to play both sound and video on your HD TV with just a simple HDMI cable.

However computers which are older than this, sometimes referred as ‘legacy’ computers, don’t come with this connectivity, instead containing older analogue formats, usually VGA, but also sometimes DVI.

To link these older machines to your digital TV you will require a VGA to HDMI converter, also sometimes known as a PC to HDMI converter. These will allow you to transfer the video from your computer to the TV, but not the audio, as these older formats don’t support audio signals.

For this you are most likely to use a simple 3.5mm headphone jack which you can plug from your old computer into the audio input of your converter, creating a complete HDMI output containing both video and audio.


There are a huge range of professional and consumer devices available for converting PC signals into digital. There are small cable-only options which are VGA only, some bigger devices which convert VGA and DVI; as well some which are capable of converting Component or Composite analogue signals to a digital HDMI output.


Got a question for the HowToAV Team?

HowToAV.tv provides a whole host of tips, tricks and technology know-how for the professional and residential AV sectors. If you have any further questions regarding HDMI then please don’t hesitate to get in touch with our team of AV experts.

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