What are the differences between DisplayPort vs HDMI?

Display Port vs. HDMIOriginal photo by Csaba Nagy

HDMI and DisplayPort are the two recognized standards for transmitting video and audio data over a single cable. Throughout the years, these two standards have evolved greatly with each new specification, each providing enhanced performance and capabilities, including major increases in bandwidth, speed, and other supported features.

Because both standards are widely used throughout the industry, it can be tough to pinpoint their differences and why one standard might be best used for certain applications. Here, we’ll help discern the two by providing their backgrounds and discussing their current features and capabilities.

Background of HDMI and DisplayPort

HDMI, or High-Definition Multimedia Interface, was first introduced in 2002 as a standard to allow for a single cable to transfer uncompressed high-definition video, multi-channel audio, and data over a single digital interface. A group of display manufacturers, including Hitachi, Panasonic, Philips, Silicon Image, Sony, and Toshiba, formed the HDMI organization to conceptualize and oversee the development of this standard.

Its conception was driven by a need for a cable to connect video sources to displays, including mainly consumer-electronics applications like DVD and Blu-ray players, TVs, and video projectors. Today, HDMI has been widely adopted and we commonly see HDMI ports on a large number of televisions and computers in our homes.

The HDMI connector includes 19 pins and offers 3 different connector types including the Standard Type-A, the mini Type-C and the micro Type-D. You might recognize the Standard Type-A HDMI connector as it is the most common.

In 2006, the DisplayPort (DP) standard was conceptualized as a new type of digital display interface, intended to phase out outdated VGA and DVI ports. It initially focused on computer displays and professional IT equipment. The DisplayPort standard is administered by the VESA (Video Electronics Standards Association), which is overseen by multiple PC and chip manufacturing companies including Apple, AMD, and Intel.

DisplayPort has 20 pins and has 2 different connector types: DisplayPort and mini DisplayPort. The mini DisplayPort was introduced by Apple and is used in various Apple MacBook PCs, swapping out the previous DVI/VGA ports. Many of Apple’s Thunderbolt ports use the mini DisplayPort connector.

HDMI 2.1 vs DisplayPort 1.4/2.0 Features and Performance

Resolution, Bandwidth, and Display Features

When comparing resolution and bandwidth between the two standards, DisplayPort’s version 1.4 delivers a maximum payload bandwidth of 25.92 Gbps over 4 lanes, and is the first standard to support 8K resolution at refresh rate of 60 Hz with full-color 4:4:4 resolution and 30 bits per pixel (bpp) for HDR-10 support. However, the most recent published DP spec, 2.0, triples the data bandwidth performance up to a maximum payload of 77.37 Gbps, and allows for several configurations with multiple displays that go beyond 8K. Like DP 1.4, DP 2.0 will feature Display Stream Compression (DSC), which enables visually lossless compression for ultra-high

definition display applications, Forward Error Correction (FEC), and HDR metadata transport.

The most recent HDMI 2.1 spec delivers a bandwidth of 48 Gbps over 4 lanes, and also supports 8K resolution with dynamic HDR at a refresh rate of 60 Hz or a 4K resolution with dynamic HDR at a refresh rate of 120 Hz. HDMI 2.1 focuses on stepping up its game for viewing games, movies, and video with its enhanced refresh rates, making the display images smoother and more seamless. Specifically, this spec adds Variable Refresh Rate (VRR) to reduce and eliminate lag, Quick Media Switching (QMS) to eliminate image delays on the screen before content is displayed, and Quick Frame Transport (QFT) to reduce latency resulting in less lag and a more real-time feel for interacting with virtual reality. HDMI can also incorporate an Ethernet channel allowing devices to share a wired internet connector that can carry data between two connected devices.

Multiple Display Capabilities

One of the major benefits of using DisplayPort is its ability to connect multiple displays together, which HDMI cannot do. One feature within the DisplayPort standard, called Multi Stream Transport feature, or MST, allows for the video source to send multiple independent video signals over a single DisplayPort output. With this feature, devices can be connected through an external hub, or as with Thunderbolt, devices can be linked together through a method known as daisy chaining.

 

DisplayPort multiple displays connected together.Photo by Tom Pijnappel

Also, with VESA’s Coordinated Video Timing standard, there is enhanced interoperability between video sources and displays, creating better compatibility with formatting, refresh rates, and timing specifications.

Unlike DisplayPort, HDMI can handle one single video and audio stream, meaning it can only support one display at a time. The MST feature in DP is not natively supported by HDMI, but can be achieved by using DisplayPort to HDMI hubs (if you have a DP connection on the source device).

Audio

While both HDMI and DisplayPort support high quality audio, HDMI includes a feature not implemented in DP called ARC, or Audio Return Channel. This feature allows users to conveniently send television audio back to the A/V receiver or any other sound system being used with one single HDMI cable; this would normally require a second audio-only cable in the mix. Furthermore, HDMI 2.1 improves the ARC function, by introducing eARC, or Enhanced Audio Return Channel, which provides improved audio quality due to the increased audio bandwidth allocation up to 37 Mbps.

Which Cable Should I Use?

These days, HDMI can be found on most television sets and is considered the standard for video and audio transmission between a video source like a DVD, Blu-Ray Player, or PC and a video display monitor. DP however, more targeted to be the go-to standard for display interfaces with computers, is also suitable for PC gaming and connecting video game consoles and video graphics cards. However, because each cable provides very similar functions for transferring video and audio, choosing between the two is a matter of your specific set up and requirements, especially as we continue to see improvements of each cable standard with each new specification release.

Comprehensively and Quickly Test HDMI and DisplayPort Cables

With the Advanced Cable Tester v2 introduced by Total Phase, cable manufacturers can now comprehensively and quickly test both HDMI and DisplayPort video standards against our set of assessments derived from the relevant cable specification from HDMI.org and VESA. We currently support:

Manufacturers can determine the quality of the video signals through our complete set of tests, including continuity testing with checks for shorts and opens, DC resistance measurements, and signal integrity testing of data lines up to 12.8 Gbps per channel. Now, instead of only performing functional tests on each cable, testers can easily insert their desired cable and determine the signal lock and overall quality cable in a matter of seconds. Cable certification is simply not enough – the Advanced Cable Tester v2 grants the ability to go beyond and uncover any inconsistencies that can and will occur during manufacturing and production.

For more information on this tool, please visit our website or email us at sales@totalphase.com.