Display Port: performance advantages over DVI (and HDMI) - Part 2 of 3

In Part 1, I talked about the inevitably of Display Port becoming the dominant display interface standard for PCs and handheld devices, if for no other reasons than cost:

1. Display Port avoids the $10k/year license fee of HDMI
2. Display Port direct-drive technology eliminates the cost for additional circuitry in computer displays

Cost aside, now I want to look at Display Port performance and features relative to the incumbents DVI and HDMI.
(Note: companies like Dell publicly contend that Display Port and HDMI will coexist to meet different product applications - but read in to what they say and you can't help but to compare!)

Ultra-thin displays

Already mentioned as a cost-reduction benefit, Display Port consolidates both external and internal display connections with direct-drive technology. From an aesthetics/performance angle this brings several significant advantages over DVI and HDMI.

• Since there is no need for display circuitry inside of the display, manufacturers can build slimmer and sleeker displays - both external monitors and laptops displays
• The LVDS display interface used inside of current notebooks can only scale to higher resolutions and color depths by using a wider cable. But you already have an increasing number of wires competing for space in the notebook display hinges. So thinner cables means thinner laptops.

Smaller connector
Display Port and HDMI offer more than twice the performance of DVI in a much smaller package than DVI connectors. And they are more user-friendly to connect - without screws!

Over 1 billion colors
Single-link DVI has enough bandwidth to display resolutions up to 1920x1200 with 8 bit color (up to 16.7 million colors) at 60 Hz. Dual-link DVI doubles the bandwidth to support a maximum resolution of 2560x1600 with 8 bit color at 60Hz.

HDMI 1.3 and Display Port both support a maximum resolution of 2560x1600 at 60 Hz with 10-bit color - that over 1 billion colors, enough to eliminate color banding and offer sufficient gamut to edit video destined for a digital cinema theater (check out the new HP DreamColor).

Longer cables
Display Port supports full bandwidth (2560×1600) transmission for cables up to 3 meters, and 1080p transmission for 15 meter cables - significantly greater than DVI (5 meters) and about the same as high-quality (but higher cost) HDMI cables.

Automatic fine-tuning
Display Port features a unique scalable bi-directional auxiliary channel that source-destination handshaking such as the display requesting stronger signal quality if the signal has too much jitter or interference. So you can have a feedback mechanism between the display and the source for automatic fine-tuning. On top of this, Display Port embeds the clock signal as part of the link stream. This means fewer wires so less RFI and better transmission.

Digital, Audio and Data
Like HDMI, but unlike DVI, Display Port can handle both audio and video (as well as data) over single cable. Since most computer displays do not include speakers, the value of audio in the stream for HDMI and Display Port is questionable for computer devices. But of course, support for audio is valuable for consumer electronics devices like TVs and it might end up be very valuable for things like digital projectors.

But unlike DVI or HDMI, Display Port is all digital and uses micro packets to bundle audio, video, and data information. This means that Display Port can freely trade off pixel depth, resolution, frame rate, and the presence and amount of audio and data in the stream. Basically this means a lot of flexibility for different devices of any type (as well as the possibility of things like picture in a picture).

The Data stream in Display Port also has some significant implications I will discuss in the next article in the series (hint: data means support for USB links, cameras, microphones, and touch-sensitive displays).

So let me do my own little score card so far:

Feature	DVI	HDMI	Display Port
Price	+1	0	+2
Sleeker Displays	0	0	+2
Smaller Connectors	0	+2	+2
Resolution & pixel depth	+1	+2	+2
Long cables	0	+2	+2
Auto-tuning	0	?	+2
Audio	0	+2	+1

Basically DVI is antiquated and struggling to keep up with the ever increasing demands of bandwidth, resolution and flexibility.

There is no clear winner between HDMI and Display Port. Display Port is rapidly making its way into the PC market, while HDMI already has a strong hold on consumer electronics. For the foreseeable future they will co-exist (but I am sure they will compete), with DVI slowly fading out of the picture.

Addendum: For the complete 3-part series on Display Port see:

• Part 1 - Cost
• Part 2 - Performance and Design
• Part 3 - Futures