Frequently Asked Questions
DVI-D & HDMI
We frequently get asked many questions about DVI and HDMI. Here's some of the most popular questions, with simple answers which will hopefully solve your queries...
- What is the difference between HDMI 1.2 and HDMI 1.3 specifications?
- What is the difference between standard speed HDMI cables and high speed HDMI cables?
- What is deep colour?
- What is Lip Synch?
- What are HD Lossless Audio Formats?
- Is HDMI Better then component video?
- What is the difference between HD and Full HD?
- Can I use my HDMI components with DVI and older versions of HDMI, is it backward compatible?
- Is 10m the maximum length of HDMI cables that I can run?
- What is HDMI, and how does it compare to DVI?
- What is "HDCP"?
- Can I connect a DVI device to a HDMI device?
- What's the difference between DVI-I and DVI-D?
- How about DVI dual link vs single link?
- Can I connect DVI-I to DVI-D?
- I want to use component video or RGB output and convert to DVI-D. Can I do this?
- Can I connect my analogue video output to HDMI?
What is the difference between HDMI 1.2 and HDMI 1.3 specifications?
There are a number of differences between the 1.2 and 1.3 HDMI specifications. The main differences of note are High Speed, Deep Colour, Lip Synch and HD Lossless Audio Formats.
Specifications for HDMI went from 1.2 to 1.2a, then 1.3, 1.3a and the latest which is 1.3b. The testing for 1.2a and 1.3 were essentially the same so a number of cables are labelled 1.3 which are in fact not able to do the 1.3b specifications.
The key factor to look for if you are wanting to have a true 1.3b cable is whether it is high speed or not.
What is the difference between standard speed HDMI cables and high speed HDMI cables?
The difference between these two is the amount of data that they will pass. Standard speed will pass up to 5gbps and high speed will pass up to 10gbps. What does this mean in the real world. Whilst a standard speed cable may pass up to 1080p resolution it will not also pass features such as 48bit deep colour or high definition sound formats such as TrueHD, nor will it pass 1200p. Currently these features are yet to be ultilised so standard speed cables are adequate. However if installing cables in walls and ceilings some consideration for future proofing is highly advised.
Note (As of Oct 2008): A number of suppliers specify their 5m+ cables as high speed. The longest distance currently available for a passive HDMI cable running high speed is just under 8m. This is only achievable with 22 or 24awg. It is currently not possible for a passive 26awg HDMI cable to run high speed over 5m. However manufacturers have been claiming this as they only have to test a small batch (shorter lengths) to certify all their cables as high speed (1.3cat2).
What is deep colour?
Simply put deep colour adds billions of more colour shades to the picture, at this stage however whilst our HDMI cables support deep colour this is not available on any blu-ray discs.
What is Lip Synch?
You may have noticed when watching DVD’s sometimes that the voices are ot of synch with the picture, HDMI 1.3 cables have the capability to auto correct lip synching problems.
What are HD Lossless Audio Formats?
These are two new audio formats which are supported by 1.3 HDMI cables, these are Dolby TrueHD and DTS-HD Master Audio. Both of these formats have more information and better sound overall then previous Dolby and DTS formats, additionally they are only available via the large bandwidth supplied by HDMI cables and are not available via traditional digital coaxial or toslink cables.
Is HDMI Better then component video?
In theory HDMI provides some visual improvements over component as it remains in the digital domain, comparatively component is converted from digital to analogue and back again. However in real life there is no visible difference when run at the same resolution. Most sources though, DVD players etc, now output their highest resolutions over HDMI. So to achieve 1080p it is often essential to use HDMI cables. One very good advantage of HDMI cables is that the signal is in a single cable, for both sound and vision, compared to three cables for component video plus a forth cable for the digital sound.
What is the difference between HD and Full HD?
Whilst not officially accepted or used by all manufactures these terms are widely accepted within the industry to mean the difference in resolutions available. HD is used for resolution up to 720p or 1080i and Full HD is used for resolutions of 1080p or higher when available.
Can I use my HDMI components with DVI and older versions of HDMI, is it backward compatible?
Yes it is, HDMI can be connected to a DVI-D with a HDMI-DVI-D cable and HDMI 1.3 can be used with HDMI 1.2, 1.1 and 1.0 without any issues. HDMI 1.0 and 1.1 carry video only.
Is 10m the maximum length of DVI or HDMI cables that I can run?
During the early days of HDMI cables some companies had problems producing cables that worked properly at 10m. DVI-D and other DVI cables will only work up to 10m. So assumptions were made that HDMI was the same. Many HDMI cables will work at standard speed at 10m, Kordz HDMI cables are capable of running standard speed HDMI up to 25m.
The majority of HDMI cables can be extended by 10m with a passive extender or 20m with a powered extender. Different lengths will also give different bandwidth and resolution.
What is HDMI, and how does it compare to DVI?
HDMI stands for "High Definition Multimedia Interface". It is the latest standard which integrates the same digital video bitstream as DVI-D (Single Link) with up to eight channels of high-res digital audio. What's more, it is a two-way communicating bus, allowing a source and display device to "talk" to each other. For example, a display device (eg Plasma screen) can tell your source devcie (eg DVD) what format it wants to run in, and the DVD can output the appropriate signal. This is of course reliant on the manufacturers making their firmware compatible with this capability. It's essentially the modern-day SCART cable, containing both picture and sound.
The picture quality of DVI-D and HDMI will be identical assuming the same standard of cable is being compared, as the video signal/bitstream is the same. HDMI differs in that it also contains audio, has communications ability, and takes up less real estate on a device's connections panel.
"HDCP" was developed to protect the intellectual property of software/movie studios and distributors. It stands for ‘High-bandwidth Digital Content Protection’), and is a digital code buried within the bitstream which is output from the digital source. This prevents unauthorised copying of protected materials, much like Macrovision did for analogue recordings. Only since the introduction of this standard have hardware manufacturers been allowed to offer DVI-D or HDMI outputs on their DVD players, High Definition TV tuners etc. Any device which bears the label "HDCP" simply means that it is complaint with the requirements. It does not change the output signal in terms of quality, it only refers to the additional code which it contains.
All HDMI products are HDCP compliant and most DVI products are. Products which are not HDCP compliant will not work with products which are. A common area where this problem is encountered is from a DVI-D video card to HDMI display.
Can I connect a DVI device to a HDMI device?
You can connect DVI to HDMI, providing the DVI is the Digital variety - ie: DVI-D. The signal is 100% compatible with no loss of quality. You can use either DVI-HDMI adapters, or a cable which is terminated with DVI-D at one end and HDMI at the other. Of course the extra features of HDMI will be forfeited (digital audio and communications bus), but otherwise it's fine.
You cannot connect DVI-I to HDMI, as HDMI is digital only. You'll find that most HDMI-DVI adapters do not have the facility for the additional four pins of DVI-I, hence a physical fit is not possible. Use only DVI-D cables with a HDMI adapter, or vice versa.
What's the difference between DVI-I and DVI-D?
It's important to first note that "DVI" (Digital Video Interface) refers to the connector, or interface, only. It's application can vary. There are three main types of DVI; DVI-I, DVI-D and a third one which is rarely mentioned, DVI-A. This latter one is DVI "Analogue", which is quite obviously analogue only. This is essentially VGA (RGB-HV) in a different plug. DVI-D is at the other end of the scale, being pure Digital video only. DVI-I combines the two, containing both analogue and digital cores.
DVI-I does NOT convert ananlogue to digital. Rather it just provides a convenient connection to offer analogue or digital in the one cable. DVI-I and DVI-D can be distinguished by the presence (DVI-I) or absence (DVI-D) of four extra pins - two above and two below the flat horizontal location pin, as follows;
How about DVI dual link vs single link?
A "Single Link" DVI connection contains three data channels for digitized RGB information (called "Transition Minimized Differential Signaling"), offering a bandwidth which can support up to 1920x1080 HD progressive resolution. "Dual Link" has a secondary parallel connection of the same digital RGB "T.M.D.S." data channels, increasing bandwidth to a supported resolution of 2048x1536 progressive.
Most AV devices output only single link, but acquiring a dual link cable often costs about the same. Dual link is fully backwards compatible with single link, but the use of a single link cable cannot support the larger bandwidth if the need arises. In other words, it's recommended to buy a dual link cable to begin with.
Single link and dual link are both applicable to either DVI-D or DVI-I, but relates only to digital information being carried; ie:- it has no bearing on the analogue part of DVI-I. Single link can be easily identified by it's lack of the centre two rows of pins in the connector, whereas dual link has all pins present. The diagrams following show this more clearly (the pins in question have been coloured RED on the dual link diagram for clarification);
Well... sometimes. Only the digital part of the signal will be relevant if they are connected, as the DVI-D connection cannot read the analogue signal which may be contained in the DVI-I. For example, if a DVI-I output of an AV device is outputting only an analogue signal, then you can't connect it to the digital-only DVI-D input of your display device, even though the plug may physically fit (although many DVI-D sockets don't have the provision for the extra pins of DVI-I, hence connection may not even be possible). You'll need to check that the DVI-I output is capable of passing DVI-D before attempting the connection. If your output device has only Analogue DVI-I, then try connecting it to the VGA input of your display device by using an appropriate adapter (Cinema Cables cannot provide such adapters).
I want to use component video or RGB output and convert to DVI-D. Can I do this?
No - there's really no point. Component video and RGB are both analogue signals (as are Composite and S-Video). To input these signals into a DVI-D connector would require an analogue to digital (A/D) conversion. Any display device which contains a DVI-D input already uses a digital circuit which contains an A/D converter for all analogue inputs. Using an external A/D converter would be unlikely to acheive any better result than that which is already built in to the display device.
The benefit of DVI-D is the lack of A/D or D/A conversion required at any stage. The pure digital signal output from a DVD player, digital TV tuner and the like would be sent to the digital display device (eg plasma, LCD, projector etc) totally intact. This yields the best possible result.
Can I connect my analogue video output to HDMI?
No. HDMI is digital only - no exceptions.