What is HDMI ARC
HDMI ARC in televisions is a connector with HDMI capabilities and the ARC function to send audio in both directions.
ARC stands for Audio Return Channel. You can use one cable to send video and audio from the receiver to the TV. You can also send audio from the TV to the receiver, soundbar, or home theater system.
Basics About the HDMI Connector
HDMI transmits video and audio digitally. This interface works with high bandwidth and sends high-definition video, which takes up a lot of digital space.
In addition to transmitting video and audio on a single channel, HDMI was designed to transmit what the industry calls a “handshake” from one device to another. They were initially designed to:
- copy protection and piracy prevention data;
- messages about what types of components have been connected;
- what are the capabilities of the connected components?
However, the HDMI transmission system was also designed to communicate more complex messages as part of Consumer Electronics Control (CEC).
CEC allows a single remote control to control the functions of 15 HDMI-connected devices. There are almost as many names for CEC as there are electronics brands: Samsung called it “Anynet +,” LG “SimpLink,” and Sony “Bravia Sync.” Unfortunately, the system has never lived up to its potential and is often mistranslated or lost between components from different manufacturers.
HDMI ARC Technology in a TV
The first versions of HDMI only sent signals in one direction: from a source, such as a DVD player or game console, to a playback device, such as a TV, projector, or AV receiver.
But most of the time, people watch TV, not movies, from external media. The TV turns from a display device into a signal source, which means another cable has to be connected. Another cable makes the “system more complicated.”
Nowadays, the TV is often the primary source of the signal because Smart TVs have streaming services.
For convenience, the cable required audio transmission in both directions. This feature allows the audio signal from the TV to go in the opposite direction to the receiver or the soundbar on the same wire.
But it is imperative to note that this is the connection of the audio-playing device to the correct HDMI port on the TV, the one with the coveted letters ARC on it.
Everything was not so smooth.
Problems of protocol
The HDMI CEC, remote control protocol commands, were regulated in 2005 in version 1.2a. But they worked poorly then and even more often within the same brand. No HDMI control for serious home theaters was out of the question.
The Samsung television failed to control LG’s home theater and refused to work with the picture.
The second pairing issue was the signals transmitted through HDMI on the main channel.
How is it? You connect one wire, and everything works.
That’s not how it worked with other brands. Denon tried transmitting digital audio between expensive devices over twisted pairs. Yamaha was not getting multichannel sound from most players over HDMI, and whether it was the player or the receiver was unclear. The variety of vendors discredited the idea of a simple unified interface.
It took four years between introducing HDMI CEC version 1.2a and regulating the reverse audio channel version 1.4. However, the feedback between the TV and the source did appear. So, let’s see what data can be transmitted over this communication channel.
The HDMI ARC protocol is analogous to the traditional digital interface for digital audio, TOSlink. It uses optical and coaxial cables.
Despite the increase in bandwidth to one megabit per second, which is 2.5 times, the number of transmitted formats compared to S/PDIF has not changed.
It is best to turn on the corresponding output to use HDMI ARC in most devices. Go to the TV audio settings and look for “audio output” or something similar. Change “TV speakers” to HDMI or ARC, and everything will start working.
HDMI ARC Audio Formats
Check which format the TV will output sound via ARC. One of the following items in the same menu is responsible for this.
The soundtrack received by the source from the media, for example, the TV from a streaming service, can be decoded by the source itself, in this case, the TV. In this case, you will see PCM and the number of channels on the receiver’s screen, such as PCM 2.0. The soundtrack can also be transmitted to the receiver in its original form for further decoding. Then, the receiver screen will light up and label it Dolby or DTS. This is selectable in the TV settings.
Transmission of the original signal without interference is most often called bitstream. Which is better, PCM or bitstream? I’m pretty sure the receiver or soundbar does the best job of decoding.
You need the receiver’s brains to do this job well. Also, the playback device may not support some varieties of Dolby and DTS formats. There are only three exceptions: Apple TV, PlayStation, and Xbox.
It is not so much the high performance of these devices as the specificity of the content presented on them. All content on these platforms is made specifically for these products, which makes them the most suitable for such tasks.
The HDMI ARC output type must be selected separately for each audio format in many models. Start the movie with Dolby Digital, enter the menu, set the bitstream, and enjoy life.
The next day, you turned on the film with DTS, looked, and PCM 2.0 was lit on the receiver’s screen. You went back to the settings and once again selected bitstream. Most often, after that, the correct DTS settings are saved.
Uncompressed multi-channel sound, in the formats Dolby TrueHD and DTS-HD Master Audio, is not available on optical, coaxial, or HDMI ARC passes.
They could have been added to HDMI ARC with HDMI 1.4 certification, as these formats have been transmitted via HDMI since 1.3. Perhaps the vendors could not agree, and the licensing organization could not wait to release the new official format, which means profiting from using it.
This means that HDMI ARC fits wonderfully for transmitting compressed audio from streaming services. But what if you download movies and play them with the built-in TV player? Don’t count on transmitting uncompressed multi-channel audio.
Can Dolby Atmos be transmitted via ARC? Yes. Due to the compatibility of all Dolby formats, Atmos is perfectly embedded in a Dolby Digital Plus stream, and as such, it will fit through the HDMI ARC.
It won’t do the same trick with DTX. It can only be transmitted via full HDMI from an external source or via eARC, which will be discussed below.
Connect the Sound to the TV or the Receiver?
The attentive user has a question: if the sound from the TV goes to the receiver on one wire, does it make sense to connect all the sources through the receiver? How about connecting set-top boxes and players to the TV so that the receiver always has one input selected?
Unfortunately, it’s not that simple. When a source transmits audio to a playback device, the output parameters are often adjusted to match the capabilities of the other.
In most cases, this means, for example, that an Apple TV connected directly to a TV will only output stereo sound because it doesn’t know that it will play the receiver and not the TV.
The second argument against this connection scheme is that sound in this form passes through the TV’s sound path, meaning it changes to suit its capabilities. This leads to the loss of multichannel sound. It was 5.1 through HDMI input, and you get 2.0 through HDMI ARC. The TV has two sound channels, so why should it decode anything else? Only a few TV models have the 5.1 option, which is rare.
So, Why Do You Need HDMI ARC?
First, connect the TV to the receiver or soundbar to remove the second wire.
Secondly, to control the system conveniently, you turn on the TV and the receiver simultaneously, and you can easily adjust the volume on the remote control.
The main problem with HDMI ARC is that the HDMI Consortium has allowed vendors to choose which protocol components they use.
Half the problem is that the HDMI CEC control protocol is used to activate and synchronize HDMI ARC, which is essentially an evolution of it. It still has frequent bugs. HDMI CEC has almost no settings inside the TV or receiver; if this protocol doesn’t work correctly, it won’t work.
The other half of the problem is that TV’s supported digital audio formats are not regulated. In theory, the TV should output any digital track without interference. That’s how the classic TOSlink digital output usually works, but it doesn’t work that way almost anywhere. Some televisions only support Dolby Digital and don’t work with DTS, while others support all tracks and downmix all tracks to 2.0. In other words, there is a chance that ARC will either not work at all, will work unstably, or will not transmit multichannel sound.
A few examples from life. Samsung TV sets in some firmware versions spontaneously turned off the HDMI ARC output. And they did it not in an hour but in a day when the installer was busy with different things. And to turn it back on with the remote control, which does not have a separate “menu” button, you had a long time to explain to the customer what to hold, where to go, and so on. LG TVs give out the same cases as other brands of receivers, but they have a more accessible menu.
Using HDMI control at all inexpensive AV processors is unrealistic and produces many errors.
Making a TV with the Android operating system is a guaranteed problem, and Sony, Philips, and all Chinese models produce multi-channel sound. Such TVs result from the work of different unrelated developers: there are hardware TV settings, operating system settings, and application settings, and they cannot randomly fit together.
For example, the Sony TV on Android has a problem. The user got tired of resetting to factory settings and bought a set-top box as a source, duplicating the TV’s functionality with a separate device. It is almost impossible to understand which device is unstable, and there are no settings.
Hence, the love of home theater system builders for Yamaha receivers. They are very likely to work correctly with the most popular televisions. The same goes for Denon and Marantz.
The smaller the manufacturer, the fewer hours its development department has spent debugging stable performance in various situations, and the more likely something will go wrong.
Picture and sound synchronization should theoretically be no problem because this feature has been added to hardware since HDMI 1.3. But its use, like many other HDMI CEC features, is optional for vendors. For example, synchronization works poorly with computers and set-top boxes, making ARC unsuitable for gamers. It creates an apparent delay of several milliseconds, which can be unnecessary in games.
What should you do if the ARC is turned off? Go to the TV settings and try to select it again. If you can’t disable HDMI Control in the TV settings, turn it off, then turn it back on, and the TV will research for the device when it is activated. Perhaps you will have to do the same with the receiver, or you will have to turn off the AVR, which supplies power to the whole home theater, and when you turn it on again, all the devices will find each other again. It doesn’t sound like a single simple protocol. In general, there is a lot of fun with HDMI ARC.
Also read: how to reboot your Vizio smart TV without or with a remote control.
How it Should Work
The ARC channel, part of the HDMI specifications, became part of version 1.4 in 2009. It makes it easy to connect your TV to your audio system.
Whether the audio signal comes from the built-in TV tuner or an external source doesn’t matter.
This can be very useful if your sound bar has only one input and you want to connect multiple sources.
With ARC technology, you can connect everything to the TV, and the TV will send the sound back to the soundbar or other external speakers.
On TVs, this port is referred to as “HDMI ARC.”
In addition, it also allows you to control most connected devices with just the TV remote.
ARC technology and CEC can simplify your home theater system in two critical ways. The first and most helpful feature of HDMI ARC is the ability to use one remote for all the most common functions of your audio devices.
You may need to go into your TV settings and activate CEC, usually in general settings. Depending on your TV’s brand, the CEC menu item may have brand-specific names (Anynet +, Bravia Sync, etc.).
When you watch a show on the TV from an over-the-air, cable, or satellite tuner, the sound is sent to an external speaker via the HDMI arc connectors. The same cable and connectors transmit video from the home receiver to the TV.
So, we do not need to connect a separate cable to transmit audio from the TV to the speaker. The signal goes through the ARC. We take an optical audio cable S/PDIF or digital audio RCA for a separate audio connection.
It is worth noting that signal transmission quality via HDMI is very high and is recommended for all connections. Ifmit an HDMI audio cable., take advantage of this
But, many users do not need ARC. This feature is unnecessary if you listen to sound mainly through the TV speakers and don’t have a receiver or soundbar. The point of ARC is to send the audio generated by or passing through the TV to an external audio device, namely a soundbar or receiver.
Video of the soundbar connection via the ARC channel to the Samsung TV:
The stand-alone speaker’s sound quality is better than the built-in TV. Therefore, purchasing a soundbar and using the HDMI ARC channel for connection is advisable.
For example, if you connect many devices to the soundbar with only one HDMI input, you can connect all of your devices to the TV, and the sound will be sent to the soundbar through the TV. There is no need for additional audio cables.
The connector on your TV is identified by its appearance. It is labeled “HDMI ARC” above it. The other pluggable device should have a connector with the same designation. The ARC function can be used only when two devices support this technology.
HDMI connectors on TVs can be labeled STB, DVI, ARC, or MHL. All of them are the same in functionality except for MHL. The ARC connector also returns sound if needed, but it works as usual on HDMI. Here, HDMI MHL combines the functionality of the HDMI interface and the MicroUSB connector, which connects smartphones to TVs. MHL may not work with a regular HDMI interface.
What is eARC
Let’s move on to eARC. This protocol was added to the HDMI 2.1 specification, but TV manufacturers could also add support for it to the HDMI 2.0 standard. Therefore, eARC is much more common than the HDMI 2.1 specification that spawned it.
When creating HDMI 2.1, the consortium tried to maximize its potential to remain the dominant technology for years. If HDMI ARC is like a one-way street with a bike path along it, the increase in bandwidth to 48 gigabits makes it comparable to two-way traffic. What does this mean?
- First, higher speeds. eARC has reached 38 megabits per second, allowing up to 32 channels of compressed audio and as many as eight uncompressed with 24-bit, 192 kHz parameters. Welcome Dolby TrueHD and DTS-HD Master Audio, DTS:X.
- Second, TVs with eARC must have the “Bitstream pass-through” mode by default, which means you can switch your system. You can connect the device to the TV and send one wire to the receiver. This is why many latest-generation soundbars have begun eliminating the built-in HDMI switch.
- Thirdly, there is no delay between sound and video, and lip sync is finally made mandatory. Playing on TV has become cool.
- However, the main difference and advantage of HDMI eARCs over classic ARCs is that they create a separate data channel for them. This allows direct communication between the eARC and compatible devices without activating the unstable HDMI CEC protocol. It also allows the devices to find and work with each other automatically and adequately without additional enabling or tinkering.
So, has HDMI eARC become the simple answer to all switching issues?
Recall that it came de facto with HDMI 2.0. Quote:
Currently, the HDMI Licensing organization has decided to remove all versions from the HDMI 2.0 specification and include them in HDMI 2.1. At the same time, all new HDMI 2.1 features are optional, and implementation is determined by the manufacturer.
Let me repeat that one more time. The decision to use HDMI capabilities is up to the vendor. In other words, the proud number 2.1 does not guarantee the consumer anything. Unexpectedly, it turned out that LG and Samsung TV sets of the latest generations, equipped with 2.1 ports, do not support all versions of DTS.
But on the TV it says that it supports everything. Again, that’s a bit of a disappointment.
Like HDMI ARC, eARC has not become a perfect protocol that always works well everywhere. However, it has undoubtedly become better, faster, and more reliable. I wouldn’t recommend using an HDMI switch built into your TV. It is better to let everything that can go directly to the receiver or soundbar go there directly.
HDMI control has also been less of a problem lately, so the system may finally become convenient.
An interface labeled eARC stands for Enhanced Audio Reverse Channel, with more bandwidth. This feature works with HDMI 2.1.
The new configuration requires eARC support from your TV and audio device. Both devices must support HDMI 2.1; older versions do not. You’ll also need an HDMI cable with Ethernet support or newer ultra-high-speed HDMI cables with Ethernet support.
Also read: The new displays from LG are designed primarily for TVs with artificial intelligence.
ARC and eARC HDMI Cables
Any cable for HDMI 1.4 and above will work with ARC. For eARC operation, you will need a high-speed cable, such as a standard HDMI to Ethernet cable or an Ultra-High-Speed HDMI to Ethernet cable.
HDMI with Ethernet cables labeled Ultra High Speed supports all HDMI 2.1 features and eARC.
Differences Between ARC and eARC
Equipment manufacturers can connect different protocols when transmitting audio over the ARC channel. Therefore, different equipment transmits different-quality audio with other audio codecs. For example, the TV may only support stereo or Dolby Digital, but DTS or 5.1 Dolby Digital may not. There are no mandatory codec sets for transport.
However, DTS-HD Master Audio, Dolby TrueHD, Dolby Atmos, or DTS: X channel ARC is unsuitable for transporting modern codec audio; here, you need eARC.
With eARC, you can connect HDMI devices directly to your TV. The TV will send uncompressed, high-quality sound to your soundbar, receiver, or amplifier directly through the eARC port.
You can output up to 32 audio channels using eARC. The eARC channel also supports 8-channel 24-bit/192 kHz uncompressed audio data delivered at a maximum rate of 38 Mbps.
Since the HDMI 2.1 specification offers faster data transfers with more bandwidth, audio and video signals can be synchronized automatically. Were there any problems with video and audio sync when there were mismatches between the audio track and video? These problems have been eliminated with eARC.
Table comparing ARC and eARC channel capabilities:
| ARC | eARC | |
|---|---|---|
| Cable | HDMI | HDMI Ethernet |
| Stereo | yes | yes |
| Compressed audio 5.1 | yes | yes |
| 5.1 uncompressed | no | yes |
| 7.1 uncompressed | no | yes |
| High bitrate & objects based on 192 kHz, 24 bit | no | yes |
| Audio bandwidth | 1 Mbit/sec | 37 Mbps |
| Video and audio synchronization | optionally | must |
| Volume control, HDMI power on | yes (CEC) | yes (CEC) |
The eARC protocol will replace the CEC (Consumer Electronics Control) control option, which allows you to control multiple devices simultaneously. CEC technology has always been supported in HDMI. A separate eARC channel now performs device detection and control.
