GUIDE-3 HDMI 2.1 48Gbps Switch with CEC Control

Thenaudio is proud to introduce GUIDE-3, a smart three-port AV switch with up to 48Gbps / FRL6 switching capability and CEC control support for extra convenience.

GUIDE-3 is engineered in a completely new way to support various audio, video, and encryption standards. In a typical AV product, the incoming signal is first decoded and then re-encoded inside an increasingly complex IC. This is generally done for multiple reasons that have to do with needing to establish a unique video path for each input signal. Since standards keep changing these methods will only work for a short period of time until a new encryption version or faster data rates are introduced. This signal decoding and re-encoding is an extremely demanding process and generally limited to 40Gbps / FRL5 for the best of the best products at the moment.

We decided to look for other ways to be completely transparent to the contents of the input signal using the fastest data rates of 48Gbps FRL6 while still allowing the much-needed CEC control support. Each input port of GUIDE-3 is equipped with a unique way to process the information exchange between the connected source and the TV in runtime while the audio and video signal is flowing untouched with perfect pass-through quality.

These innovations allow GUIDE-3 to support any HDMI video signaling all the way to the latest standards found from the 2.1 specification. GUIDE-3 can support 4k120 10/12bit HDR, 8k60, and any other format up to 48Gbps while including features such as VRR for the best gaming experience. For audio support, there are no limitations, and all standardized audio formats such as all flavors of Dolby Atmos / DTS:X / PCM 7.1 are supported including all standard sample rates like 48kHz to 192kHz.

GUIDE-3 is also capable to support CEC control. CEC control is a desired feature to use in modern AV setups since most TVs sold in the past several years offer CEC control simply by using the TV remote controller. TV menus are often engineered to natively support this feature, yet many switches have never added the capability due to the additional complexities to support these commands while making the CEC network reflect the correct parameters.

An example of GUIDE-3 using three connected devices, XBox One X, Blu-Ray player and AppleTV is shown below. Each source is connected to one of the GUIDE-3 inputs and the output is connected to the HDMI 3 of an LG TV. TV will scan the CEC network and display each capable source under HDMI 3 as this is the input where GUIDE-3 is connected. By using the remote it is simple to switch between the inputs. The actual switching happens automatically inside GUIDE-3.

CEC channel switching example

Another way to start watching the desired source is to press the menu button on the remote controller for the respective input source. For example, pressing the AppleTV remote controller menu button will issue a string of specific CEC commands which GUIDE-3 will process accordingly to make the channel change.

There are other ways to perform channel switching with GUIDE-3. In case CEC control is not available, it is possible to use a simple “+5 switching”. There is a rudimentary way that HDMI sources use when informing their presence when connected to a sink device. They do it by showing a fixed voltage level that can be detected by the connecting device. Whenever such voltage is detected GUIDE-3 will switch to this channel if the relevant feature is enabled using the DIP switches on the side of GUIDE-3.

In case GUIDE-3 is installed within a system that has system controllers then it is possible to use IR control for channel selection. The IR hex codes are available in the download section.

For use cases without an IR system controller, there are special additional IR commands that GUIDE-3 can respond to. This means it is possible to use an already existing remote controller, say, from an AVR to do the switching. Such support is generally ongoing and will be added depending on the number of requests for specific models.

Finally, there is also a manual push-button that cycles through the inputs in case no automation is desired.

ZONE-2 Processor, a Case Study

ZONE-2 eARC Audio Processor adds to the Thenaudio portfolio of eARC audio processors by introducing a way to extract and forward the original lossless audio received from a TV eARC port.

ZONE-2 builds on top of the already well known and popular SHARC eARC Audio Converter. SHARC is used in situations where you have a modern eARC TV and want to keep your existing audio system. SHARC will interface the two and you don’t need to purchase a new audio system for years to come. ZONE-2 has the same capabilities as SHARC and adds the capability to also forward the eARC audio to another zone.

For those who already have made the investment and purchased a modern soundbar, HDMI2.1 AVR, or another modern eARC sound system, ZONE-2 eARC Audio Processor will now enable the extraction and forwarding of a lossless audio stream from TV. This is useful for multiple scenarios that will be highlighted below.

HDMI 2.1 AVR Audio Splitting: If you have purchased a brand new modern HDMI2.1 AVR with eARC capabilities you can find yourself in a situation where forwarding audio is impossible. Depending on your model capabilities you either can’t route eARC audio anywhere or in some cases can only route a downmixed or transcoded signal. Using Zone-2 eARC Processor in between your TV and the AVR allows you to extract the original lossless audio and share it to a second zone with no degradation in the audio resolution or format.

Adding a Subwoofer: Let’s take an example of Sonos ARC soundbar. This new popular soundbar is capable of playing Atmos audio and does a very good job of producing a fantastic audio experience. In some situations, a user may still want to boost the bottom frequencies by introducing a subwoofer. Currently, this is not possible as you cannot get access to the audio signal “in-between” TV and Sonos ARC. However, with the use of ZONE-2 eARC Audio Processor, you can now extract the audio signal while having a connection between TV and Sonos ARC. This extracted audio signal can then be used to power a subwoofer amplifier using HDMI audio, optical SPDIF, or analog headphone connections. ZONE-2 audio signal is a perfect pristine representation of the original content. Your amplifier will perform the signal decoding and can therefore retain the full lossless accuracy.

Adding Second Room Audio: With a similar soundbar setup as above, you are able to route the standard HDMI audio signal to any additional room or zone in your house.

State of the eARC


TV manufacturers tend to be drivers for new functionalities, features, and ever-improving video quality. It is understandable as it is the TV that always drives the user experience for the picture quality.

It is in consumer’s best interests to connect source devices such as PlayStation, Xbox, streaming players like Apple TV, and Blu-Ray players directly to the TV input ports rather than using a device such as an Audio Video Receiver to handle channel switching.

This has been increasingly important already over the past many years. Right now predominantly all new TVs in all price categories accept most flavors of HDR and the latest models already widely accept Variable refresh rates (VRR) and auto low latency modes (ALLM) which are indispensable for any gamer. Also, we already have Quick Sync and early HDMI 2.1 8k formats.

Such formats as described are accepted by nearly none of the current audio systems or repeater/matrix systems.

With this rapid evolvement of video formats, it is clearly not advisable to invest in those “man in the middle” devices which could easily be lacking a simple new feature rendering the device obsolete in a matter of months. We are living in a time where standards greatly change within a short period of time.

To discuss the development of the audio side we must investigate the past to see how sound formats got to be where they are.

In early 1990’s Dolby Digital was introduced. In the early 2000’s lossless high bit rate audio formats Dolby TrueHd and DTS-MasterAudio were created. In 2012 metadata object-based audio was introduced. These are the Dolby Atmos and the DTS-X formats. All these audio formats have been extremely popular together in most video content and continue to enjoy wide acceptance today.

An audio system purchased since 2012 already supports everything a Blu-ray / streaming content can throw at it. Why is this not highlighted more and why have customers still been upgrading audio receivers after 2012? How do audio system makers stay in business?

The reason is that each change in the video standard, even offering a single new HDR format, requires a purchase of a brand new Audio Video Receiver to pass such a signal to the TV. Each model after 2012 really only improve the video side and possibly add some new services from cloud vendors depending on the model.

The great new paradigm shift for HDMI audio came in late 2017 when the HDMI 2.1 specification was released and along with it the specification for a new audio transport called eARC – enhanced audio return channel. This is an upgrade to the legacy ARC specification already available since early HDMI 1.4 specification.

It is revolutionary because now there is a method to transport non-retouched lossless audio all the way from the original content to the amplifier via TV, something only an AVR could offer before using a direct connection to the source device.

AVR manufacturers have been understandably slow to adopt eARC because surely why detract from the only driving force that requires consumers to upgrade audio systems. This eARC, if widely accepted, would work towards removing the need of upgrading due to the video format evolvement.

Thenaudio has recognized this trend and the disconnection between the development of the audio and video formats in the past years. We offer solutions that finally enable consumers to get past the need to upgrade a perfectly sufficient working equipment.

Our products, such as SHARC eARC Audio Converter and ZONE-2 eARC Audio Processor harness the new eArc transport found in TVs and activate your current perfectly capable sound system for the latest lossless audio formats. Years ago you may have spent hundreds or thousands of dollars thinking your sound system will be good forever, just to find out that a year later it already was lacking in functionality.

Unfortunately, today the situation is still the same. If you were to finally buy a new receiver, today, or six months from now you may already be missing an important new video-related capability or never get the functionality you were promised. This is the case with the current HDMI 2.1 announced receivers due to a new bug as outlined in articles such as Bug in HDMI2.1 chips.

Please take a look at our Thenaudio products to learn how they will enable what you already have for the best possible audio experience without sacrificing anything in the video performance.

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