Part III – HDMI Demystified: Exploring the Features

April 30, 2024 Part III – HDMI Demystified: Exploring the Features

An Introduction to HDMI Features

So far in our journey through the realm of HDMI technology, we’ve explored the evolution of HDMI cables and the significance of different versions. Now, we embark on a deeper dive into HDMI features inherent to the interface and how they shape our entertainment experiences.

Understanding HDMI features is key to optimising audio-visual setups. Unlike HDMI cables, which physically transmit signals, HDMI features define how these signals are interpreted and utilised by devices. Whether configuring a home theatre, gaming console or professional AV setup, familiarity with HDMI features empowers integrators to make informed decisions, ensuring seamless compatibility and optimal performance.

As we delve into HDMI features, we’ll explore various aspects that enhance audio-visual experiences. From audio capabilities to visual performance, we’ll uncover the intricacies and practical uses of each of the features the integration community needs to know about. Special features will reveal hidden and seldom used functionalities, while considering future-readiness will prepare you for emerging HDMI technologies. Many of these features are optional, so please keep in mind that not every feature is enabled on every product.

Audio Features

Audio plays a vital role in delivering the captivating audio-visual experiences that HDMI technology facilitates. HDMI supports a wide range of audio capabilities, ensuring that sound quality matches the visual fidelity. From basic stereo to advanced multichannel and surround sound formats, HDMI is capable of delivering rich and immersive audio experiences.

HDMI technology offers two audio features: 

• Audio Return Channel (ARC) allows audio signals from the display device to be sent back to the AV receiver over the same HDMI cable using the HEAC lines.
• Enhanced Audio Return Channel (eARC) is an advanced version of ARC that supports higher-quality audio formats and greater bandwidth.

These are the available audio formats:

• Stereo Audio is a basic two-channel audio format commonly used for standard audio playback including CD and SACD quality.
• Single Layer Multichannel Audio supports audio formats with more than two channels, such as 5.1 or 7.1 surround sound.
• Immersive Layer Surround Sound provides immersive audio experience by placing sounds in different directions around the listener up to 32 channels.
• High-Definition Audio supports lossless audio formats like Dolby TrueHD and DTS-HD Master Audio for superior sound quality.

These audio formats are transmitted alongside video signals through an HDMI cable’s Transition Minimised Differential Signalling (TMDS) or Fixed Rate Link (FRL) lines as metadata. This means that the audio data travels from the source device to the display or audio receiver through these dedicated transmission lines, ensuring synchronicity between audio and video for a seamless viewing experience.

In terms of the audio features: 

• ARC enables audio signals (up to 8 channels) from the display device to be sent back to the AV receiver over the same HDMI cable, eliminating the need for additional audio cables.
• eARC is an advancement of ARC, supporting higher-quality audio formats such as Dolby Atmos and DTS:X up to 32 channels, along with greater bandwidth for uncompressed audio transmission. This ensures that audio is delivered with uncompromised clarity and fidelity, enhancing the overall listening experience. (For a deep dive into eARC, click here.)

It’s important to note that ARC and eARC signals are transported on the associated lower-speed lanes of the HDMI cable. This means that when selecting HDMI cables, especially Active Optical Cables (AOCs), users must ensure that all functionality is supported. When choosing an HDMI cable, you need to carefully consider both compatability and audio performance, including factors like common mode vs. single mode transport and compatibility with features like Consumer Electronics Control (CEC). Keep in mind that ARC uses the same channel as CEC, which means sometimes you need to turn CEC on. On the other hand, eARC uses a separate channel, which may help to simplify programming and automation in situations where CEC may create control conflicts by inadvertently taking control of HDMI-enabled devices.

Video Features

The HDMI interface supports a wide range of video resolutions to accommodate various display needs. Starting from standard definition (SD), which offers a resolution of 720×576 pixels for PAL and 720×480 pixels for NTSC, HDMI gradually progressed to high definition (HD). HD resolutions include 1280×720 pixels, commonly known as 720p, and 1920×1080 pixels, known as 1080p or Full HD.

Evolving further, HDMI embraced ultra-high-definition (UHD) resolutions such as 4K, 5K, 8K and 10K. 4K resolution boasts a pixel count of 3840×2160, providing four times the detail of Full HD. It delivers incredibly sharp and clear images, making it ideal for larger screens and closer viewing distances. On the other hand, 8K resolution takes visual fidelity to the next level with a pixel count of 7680×4320, offering an even more immersive viewing experience with unparalleled detail and clarity.

Other features of HDMI video technology include: 

• Source-based tone mapping was integrated into HDMI 2.1, representing an advanced feature of HDMI that enables compatible devices to optimise HDR content for display on screens with varying capabilities. With source-based tone mapping, the HDR metadata embedded in the content is analysed by the source device, enabling it to adjust the tone mapping process according to the specific characteristics of the display. This ensures that HDR content is rendered accurately and optimally, regardless of the display’s capabilities, resulting in a consistent and high-quality viewing experience across different devices. By dynamically adapting the tone mapping process at the source level, source-based tone mapping enhances compatibility and ensures that viewers can enjoy HDR content as intended, without the need for manual adjustments or compromise to visual quality.
• Deep Colour plays a crucial role in enhancing the visual experience by enabling a wider range of colours and more accurate colour representation. Different colour standards like BT.2020, BT 709 (REC709), sRGB, and DCI-P3 offer varying colour spaces, each with its own characteristics and suitability for different types of content and displays. The BT2020 format that offers the widest colour range, covering around 57% of all colours the human eye can see and almost 100% of colours reflected by the sun, leaving only colours such as neons outside of this range.
• High Dynamic Range (HDR) significantly improves the contrast and brightness of images, resulting in more realistic and lifelike visuals. It enhances the details in both the brightest and darkest parts of the image, leading to a more immersive viewing experience. It achieves this by taking the normal 300 nits of Standard Dynamic Range to well over 1,000 nits. Dynamic HDR takes this further again by dynamically adjusting settings on a scene-by-scene basis, ensuring optimal visual quality for every moment of the content. This dynamic adjustment significantly improves image quality, since the human eye’s iris also makes these adjustments naturally from bright to dark environments.
• Extended Display Identification Data (EDID) supports good video quality by enabling proper communication between devices. EDID plays a crucial role here by enabling devices to exchange information about supported resolutions and formats. It ensures that the source device sends the appropriate signals and the display device properly interprets and renders this complex content along with all the variables in real time. Therefore, selecting certified HDMI cables that support the necessary data transfer rates and EDID communication is essential for ensuring seamless compatibility and optimal video quality across the entire audio-visual setup.

Special Features

In addition to its core functionalities, HDMI offers a range of special features designed to enhance the overall audio-visual experience:  

• HDMI with Ethernet integrates network capabilities into the HDMI connection. In theory, this allows devices to share an internet connection without the need for separate Ethernet cables, simplifying connectivity and reducing cable clutter; however, its implementation within products has been almost non-existent.
• Consumer Electronics Control (CEC) is another notable feature that enables interconnected HDMI devices to communicate and control each other. With CEC, users can use a single remote control to operate multiple devices, such as switching inputs or controlling volume, enhancing convenience and ease of use. However, CEC can be a double-edged sword; on one hand it can simplify AV setups, on the other, if you are using a control system it’s usually best to make sure it’s turned off in every device to make sure you don’t have any unintended behaviour. It’s often the case that for ARC to work, CEC must be turned on in the device menu of both the TV and the AV receiver or soundbar.
• Lip Sync is a useful feature that addresses the issue of audio-video synchronisation, ensuring that sound aligns perfectly with the corresponding visuals. By automatically adjusting audio delay to match the video output, Lip Sync eliminates the distraction of mismatched audio and video, providing a more immersive viewing experience.
• Variable Refresh Rate (VRR) and Auto Low Latency Mode (ALLM) enable gamers to improve their performance. VRR synchronises the refresh rate of the display with the output frame rate of the graphics card, reducing screen tearing and stuttering for smoother gameplay. ALLM automatically switches the display to a low-latency mode when gaming is detected, minimising input lag and ensuring responsive gameplay.
• High Frame Rate (HFR) enhances the viewing experience by delivering smoother motion in high-action content. Whether it’s sports events, action movies, or gaming, HFR ensures that fast-paced scenes are rendered with clarity and fluidity, reducing motion blur and maintaining image sharpness.
• Soft Start is another valuable feature offered by HDMI, facilitating a gradual system power-up process to prevent sudden surges that could potentially damage connected devices. This gradual power-up mechanism ensures the stability and longevity of the audio-visual setup, protecting against voltage spikes and electrical stress.
• HDCP (High-bandwidth Digital Content Protection) is essential for maintaining content security in HDMI-enabled devices. HDCP encrypts digital content transmitted between devices, preventing unauthorised interception or piracy. This ensures that copyrighted content remains protected throughout the transmission process, maintaining the integrity of digital rights management (DRM) mechanisms.
• Fast Switching is a practical feature that enables seamless transitions between different HDMI sources, allowing users to switch between devices with minimal delay or interruption. Whether it’s switching between gaming consoles, Blu-ray players, or streaming devices, Fast Switching ensures a smooth, snappy and uninterrupted viewing experience, eliminating downtime and enhancing user convenience.

Future-Readying Systems with HDMI Features

In the fast-paced world of audio-visual technology, future-readying your setup where possible is essential to stay ahead. HDMI features play a crucial role in ensuring compatibility with upcoming advancements, making it imperative to understand and leverage these capabilities.

When considering HDMI devices, it’s important to ensure compatibility with advanced features. Features like Consumer Electronics Control (CEC) and Lip Sync enhance connectivity and user experience but may not be supported by all devices. So remember to opt for HDMI-enabled devices that support a wide range of features to ensure future compatibility and functionality.

Selecting the Right HDMI Cable

Selecting the right HDMI cable is crucial to ensuring long-term reliability and performance in your audio-visual setup, as not all cables support all HDMI features and they can cause compatibility issues. Opting for cables that are fully tested and/or certified to meet HDMI specifications, preferably from reputable brands, ensures that all features are supported, saving you and your customers time, money and hassle in the long run. Kordz has earned a reputation worldwide for excellence in HDMI cables, with a product range known for its quality, reliability, and innovation. Focusing on both problem-solving and user-friendly design, Kordz has consistently provided solutions to common HDMI issues, from ensuring compatibility with the latest standards to minimising signal loss. By investing in putting Kordz HDMI cables in your audio-visual systems, you can mitigate many common issues, such as signal degradation, compatibility issues and unreliable performance, ensuring long-lasting reliability and peace of mind. Visit hdmi.org/adopter/adoptersaffiliates for a list of official HDMI adopters, including Kordz, and discover the right cable solution for your next integration job.

For a handy reference table of the features of each HDMI standard and the associated Kordz products that offer them, please see here.

Conclusion

In the ever-evolving landscape of audio-visual technology, leveraging HDMI features is essential for staying ahead. By understanding and embracing these capabilities and fitting cable from a reputable brand, installers can future-ready their setups, ensuring compatibility with emerging technologies and maximising their entertainment experiences. 

To discover Kordz’ award-winning range of HDMI cables, please check out our products.