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What is HDMI?
HMDI (High Definition Multimedia Interface) is an interconnectivity standard supported by most major video and multi-media electronic manufacturers, such as Hitachi, Panasonic (Matsushita Electric), Philips, Silicon Image, Sony, Thomson, Toshiba, and many others. The HDMI standards are formed by the HDMI LLC which is a non-profit industry organization created to bring in a new era of superior performing digital high-definition video and multi-channel audio connectivity. HDMI signals carry video, audio and other inter-component commands (remote control signals) on one digital interface built on the success of DVI systems. It offers new features not available in any other standard while maintaining full backward compatibility.
HDMI Advantages
- Single Connector for Uncompressed High Definition Video (including 1080p) and 8 Channel High Fidelity Digital Audio
- Supports All Current Video Standards Including Lossless Standards
- Fewer Cables Provides for a Simpler and Cleaner Installation
- Smaller Connector Size Allows for Easier Installation through Wall Cavities and Stud Construction
- HDMI uses same TMDS technology for video transmission as DVI Systems Ensuring Compatibility
- HDTV uses Less than 50% of HDMI's Available 4.95 Gbps Bandwidth and Less Than 25% of the Bandwidth of the New HDMI 1.3 Standard Allowing for New Technology Advancements Long into the Future
- HDMI is becoming the Consumer Electronics Industry Standard for Connecting all Audio/Video Devices and the Use of DVI Connections is Expected to Diminish Especially in Multi-Media Audio and Video Systems.
Online Video Tutorial For an online video tutorial explainging the benifits and uses of HDMI technologies click on the following link (A high speed DSL or Cable Modem is Suggested):  Understanding HDMI To truly understand what HDMI is we must first understand the DVI standard. DVI (Digital Visual Interface) is an uncompressed digital connection scheme developed for the PC industry. It was designed to serve as a low-cost, high-bandwidth digital connection standard between PCs and digital monitors. DVI is now the most widely used digital display interface in the computer industry. DVI in home theater applications may be combined with High-bandwidth Digital Content Protection (HDCP) technology to create a protected digital connection that prevents unauthorized duplication of appropriately encrypted programming. DVI is a copper-based electrical interface that uses TMDS (Transition Minimized Differential Signaling). TMDS was developed by Silicon Image Inc. for transmitting high-speed serial data. While commonly used in the realm of PC’s, DVI connections on home theater products are found primarily on projectors, monitors, and advanced DVD players.
See our DVI Tutorial for more information on DVI connection types and DVI system performance.
 HDMI Video Performance
HDMI uses same TMDS technology for video transmission. HDMI and DVI video signals are identical which makes for easy conversion between connection formats. Thus an HDMI device gets all of the digital video performance DVI can deliver, up to and including 1080p.
There are seven digital video formats currently in use. These are 480i, 480p, 576i, 576p, 720p, 1080i, 1080p. Of the seven only the last three are true high-definition formats. All versions of HDMI 1.0 and beyond are capable of supporting a 1080p image, the most demanding of all the high definition formats. You do not require an HDMI 1.3a interface or cables to enjoy a 1080p image. Additionally, there is nothing in the HDMI 1.3 standard which improves the quality of existing systems the increased bandwidth and color depth offered by HDMI 1.3 are for future applications only.
HDMI Audio Capabilities
HDMI also offers significant advantages over existing and previous analog audio interfaces. It supports up to 8 channels of uncompressed PCM audio of up to 192kHz at up to 24 bit sampling rates. It supports all existing compressed audio formats as well such as Dolby Digital 5.1 to 7.1, Dolby Digital Plus, S/PDIF, DTS, DTS-EX, DVD-Audio (DVD-A) or SACD (Super Audio CD), Ambisonics, quadraphonic, MP3, and MP3 Surround, and other formats. It now supports the new high bit rate lossless audio formats for surround audio such as Dolby True HD and DTS HD Master Audio which are the same audio formats used in movie theaters.
HDMI multi-channel audio supports DVD-Audio (DVD-A) or SACD (Super Audio CD), Ambisonics, quadraphonic, Dolby 5.1 Surround sound, DTS, DVD-Video (DVD-V), MP3, MP3 Surround, and many other multi-channel digital audio systems.
HDMI Cables
There is no set maximum length for HDMI cables rather there is a minimum electrical performance that a cable must meet with at each length. Typically the maximum length for most manufacturers is limited to 5 meters (16.4 feet) especially when displaying high resolution images at 1080p. Some cable manufacturers (Including AVDgear’s HDMI cables) can reach lengths of around 20 meters (65.6 feet) while still meeting or exceeding the minimum electrical performance levels required by the HDMI standards.
There are repeaters available to extend the cable runs beyond the cable limit and these vary in price and performance. These systems decode, encode, and retime the video signals and the more robust systems boost the signal actively with electronics, beware of devices that claim to boost the signal or extend your cables passively when going beyond 20 meter cable runs.
The small size format of the cables connector body makes it easy to pass through small holes (7/8 inch) in the wall or studs. This makes it very easy to pull cable for the video monitor, LCD, or Plasma HDTV. We recommend that all cables be tested with the devices prior to full installation to ensure that the desired performance is achieved before time consuming installation.
Converting Between HDMI and DVI Devices
All home theater applications supporting DVI utilize the DVI-D standard in a single link configuration. This is why all adapters and conversion cables between HDMI and DVI are manufactured as single link instead of a double speed dual link connection. DVI-D single link supports images up to 1920 x 1080 lines with progressive scan rates or more commonly referred to as 1080p.
HDMI connections are very straight forward the HDMI cable always has a male end (or plug) while the HDMI connection at the video device uses a female end (or jack). There are some occasions where changing the gender between formats might be desired. In these cases there are HDMI adapters available to fill these needs in male to male, male to female, and female to female types. We offer a complete range of HDMI adapters to fill these needs.
HDMI Standards
There are various versions of the HDMI specification from 1.0 to the current 1.3. Each version of the specification has kept backward compatibility while increasing the bandwidth, color depth, audio performance, and/or other system capabilities. See the comparison chart below for a sampling of the changes in the HDMI standards:
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HDMI |
Bandwidth |
Color Depth |
Audio |
Date |
Other |
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1.0 |
165MHz (4.95Gbps) |
24bit |
8 Channel |
Dec 2002 |
Single-Cable Digital Audio/Video Connection |
|
1.1 |
165MHz (4.95Gbps) |
24bit |
8 Channel |
May 2004 |
Content protection added for DVD Audio |
|
1.2 |
165MHz (4.95Gbps) |
24bit |
8 Channel |
Aug 2005 |
Added Support for One Bit Audio, used on Super Audio CDs |
|
1.2a |
165MHz (4.95Gbps) |
24bit |
8 Channel |
Dec 2005 |
Full Compliance with Consumer Electronic Control (CEC) Features, Command Sets, and Testing Methods |
|
1.3 |
340MHz (10.2Gbps) |
24bit |
8 Channel |
Jun 2006 |
Single-Link Bandwidth Increased to 340 MHz with a Maximum Bit Rate of 10.2 Gbps |
|
1.3a |
340MHz (10.2Gbps) |
48bit |
8 Channel |
Nov 2006 |
Increased Color Depth to Maximum of 48bit. Added Lip Sync Cabability. Added New Mini Connector Capability for Portable Video Devices. Added Support for TrueHD and DTS-HD Digital Audio |
Notes:
- Deep Color (Extended-Gamut YCC (xvYCC)) defines colors by means of an algorithm that can specify any color in nature and is a format used in professional video electronics that is capable of supporting 1.8 times as many colors as RGB. This color performance improvement is significant only in specifications since it is not used by any current or planned consumer electronics and since current HDTV broadcasts uses only 8-bit color depth. Deep Color capability expands the number of colors viewable from millions to billions while eliminating color banding and subtle gradations between colors through the use of 10-bit, 12-bit, and 16-bit color depths. While the new Deep Color format could provide an improvement in picture quality, there currently is no content (no movies, TV shows or archived material) available that can be easily transferred into this new system. With the existing issues of Digital Rights Management (DRM) and High-bandwidth Digital Content Protection (HDCP) just beginning to be worked out it is highly unlikely that Hollywood or any entertainment industry will rush to provide software that is equal to that of the original movie quality. The first place Deep Color is likely to be used is in advanced gaming systems, but even that milestone seems beyond the immediate future.
- TrueHD and DTS-HD are lossless audio codec formats used on HD DVDs and Blu-ray Discs. If the disc player can decode these streams into uncompressed audio, then HDMI 1.3 is not necessary, as all versions of HDMI can transport uncompressed audio.
- Automatic audio syncing (lip sync) capability is a system that will automatically adjust for the difference in electronic latency between the processing circuits of the sound and image. This discrepancy sometimes manifests itself as a slight delay in the sound compared to the image.
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