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HDMI Tutorial
HDMI, or High Definition Multimedia Interface, is a compact audio/video connector interface designed to transmit uncompressed digital audio and video streams. It represents a digital alternative to consumer analog standards such as coaxial cable, composite video, S-Video, component video, and VGA.
HDMI connects digital audio/video sources such as set-top boxes, Blu-ray Disc players, personal computers, video game consoles, and AV receivers to compatible digital audio devices, video monitors, and digital televisions. The world's first HDMI products started shipping in the fall of 2003 and currently over 800 companies have adopted the HDMI specification (www.hdmi.org). HDMI began to appear on consumer HDTV camcorders and expensive digital still cameras in 2006. HDMI usage is expected to exceed DVI in 2008, driven primarily by consumer electronics.
HDMI supports, on a single cable, any TV or PC video format including standard, enhanced, and high-definition video along with up to 8 channels of digital audio. It is independent of the various digital TV standards such as ATSC and DVB, as these are encapsulations of the MPEG movie data streams. HDMI encodes the video data into TMDS for transmission digitally over HDMI.
Devices are manufactured to adhere to various versions of the specification, where each version is given a number, such as 1.0 or 1.3. Each subsequent version of the specification uses the same cables, but increases the throughput and capabilities that can be transmitted over the cable. HDMI 1.3 increased the transmission speed to 340 MHz, providing support for WQXGA (2560x1600) and beyond across a single digital link. HDMI also includes support for 8-channel uncompressed digital audio at 192 kHz sample rate with 24 bits/sample as well as any compressed stream such as Dolby Digital, or DTS. HDMI 1.3 supports up to 8 channels of 1-bit audio and lossless compressed streams such as Dolby TrueHD and DTS-HD Master Audio.
HDMI is backward-compatible with single-link
DVI carrying digital video,
DVI-D or
DVI-I. Therefore, a
DVI-D source can drive an HDMI monitor, or vice versa, by means of a suitable adapter or cable. However, the audio and remote control features of HDMI will not be available. Additionally, without support for High-bandwidth Digital Content Protection (HDCP) on the display, the signal source may prevent the end user from viewing or recording certain restricted content. Computers and TVs with hardware HDMI output may require software support from operating systems for HDCP support.
Connectors
HDMI specifications include three connectors, each intended for different markets:
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Type A HDMI is the standard connector and has 19 pins with bandwidth to support all SDTV, EDTV, and HDTV modes. Plug dimensions are 13.9mm X 4.45mm. Type A is electrically compatible with single-link DVI-D.
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Type B HDMI is a higher resolution version with 29 pins, allowing it to carry an expanded video channel for very high-resolution future displays such as QXGA and WQUXGA (3840x2400). Type B is electrically compatible with dual-link DVI-D but is not in general use.
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Type C HDMI, or Mini HDMI, is intended for portable devices. Its 10.4mm X 2.4mm dimensions are smaller than the Type A connector, but it has the same 19-pin configuration. It can be connected to a Type A connector using an HDMI Type A to Mini HDMI Type C cable.
Cable length
The HDMI specification does not define a maximum cable length, but construction quality and materials enable higher performance. HDMI 1.3 defined two categories of cables: Category 1 certified cables to be tested at 74.5 Mhz (1080i/720p) and Category 2 certified cables to be tested at 340 MHz (1600p). A 16FT (5M) cable can be manufactured easily and inexpensively to Category 1 specifications using 28 AWG. Higher-quality construction using 24 AWG wire, tighter tolerances, better jacketing materials, better contact plating metals, etc can reach lengths of 50FT (15M). Long cable lengths can cause instability of HDCP, as the signals must be multiplexed with TMDS video signals.
Where it’s used
Blu-ray offers new high-fidelity audio features that require HDMI for best results. HDMI 1.3 supports Dolby Digital Plus, Dolby TrueHD, and DTS-HD Master Audio and can transport their bitstreams in compressed form.
Specifications for HDMI Revision 1.3 (including 1.3, 1.3a, 1.3b, 1.3b1)
Overview of HDMI 1.4
What’s new in the HDMI 1.4 specification?
- HDMI Ethernet Channel
The HDMI 1.4 specification adds a data channel to the HDMI connection, enabling high-speed, bi-directional communication. Connected devices that include this feature can send and receive data via 100 Mb/sec Ethernet, making them instantly ready for any IP-based application. The HDMI Ethernet Channel allows internet-enabled HDMI devices to share an internet connection via the HDMI link, with no need for a separate Ethernet cable. It also provides the connection platform that will allow HDMI-enabled components to share content between devices.
- Audio Return Channel
The new specification adds an audio channel that will reduce the number of cables required to deliver audio “upstream” from a TV to an A/V receiver for processing and playback. In cases where a TV features an internal content source, such as a built-in tuner or DVD player, the Audio Return Channel allows the TV to send audio data upstream to the A/V receiver via the HDMI cable, eliminating the need for an extra cable.
- 3D
The 1.4 version of the specification defines common 3D formats and resolutions for HDMI-enabled devices, enabling 3D gaming and other 3D video applications. The specification standardizes the input/output portion of the home 3D system, facilitating 3D resolutions up to dual-stream 1080p.
- 4K Resolution Support
The new specification enables HDMI devices to support extremely high HD resolutions, effectively four times the resolution of a 1080p device. Support for 4K allows the HDMI interface to transmit digital content at the same resolution as the state-of-the-art Digital Cinema systems used in many movie theaters.
- Expanded Support For Color Spaces
HDMI now supports color spaces designed specifically for digital still cameras, enabling more accurate color rendering when viewing digital photos. By supporting sYCC601, Adobe®RGB, and Adobe®YCC601, HDMI display devices are capable of displaying more accurate, life-like colors when connected to a digital camera.
When should we expect to see products with some of these new features?
While the HDMI Licensing authority has no special insight into manufacturers’ product plans, prior experience tells us that when a new version of the specification is released, products featuring the new capabilities typically start to reach the market within six to nine months. A number of products featuring HDMI 1.4 functionality are likely to be introduced at the 2010 Consumer Electronics Show in Las Vegas.
Are manufacturers required to implement all of the new HDMI 1.4 features?
No. HDMI technology is designed to enable a wide variety of manufacturers in different markets to implement the feature sets that work best for their customers.
How will I know which HDMI 1.4 features are implemented in a device?
Shop for the specific features that interest you, rather than shopping for an HDMI version number and assuming that a certain feature is supported. Since many of the capabilities detailed in the HDMI 1.4 specification are optional implementations, it’s the responsibility of the manufacturer to tell you what features are supported in any given device.
Will any of the new HDMI 1.4 features require a new cable?
The HDMI Ethernet Channel feature will require a new cable that supports this functionality, either a Standard HDMI Cable with Ethernet or a High Speed HDMI Cable with Ethernet, depending on the maximum resolution to be supported. The Automotive Connection System will also employ a new class of cable, the Standard Automotive HDMI cable, which is designed specifically for automotive use. All of the other new HDMI 1.4 features will be compatible with the existing categories of cables.
Are HDMI 1.4 devices going to be backwards-compatible with older HDMI (v.1.0 - 1.3) devices?
Yes, devices built to the HDMI 1.4 specification will be fully backwards-compatible with existing HDMI devices and their features.
Can older HDMI (v.1.0 - 1.3) devices be firmware-upgraded to take advantage of the new features introduced in HDMI 1.4?
Probably not. Most of the new features introduced in HDMI 1.4 will require a new HDMI chip to enable, and cannot be upgraded via firmware.
HDMI Ethernet Channel
What will I be able to do with an HDMI Ethernet Channel -enabled device?
The HDMI Ethernet Channel enables a number of new possibilities via the HDMI link, including:
- Sharing an internet connection – The HDMI Ethernet Channel feature allows your internet-ready entertainment devices, from gaming consoles to Blu-ray Disc players and more, to share an internet connection without any need for a separate Ethernet cable.
- Content distribution – Devices connected by the HDMI Ethernet Channel will be able to exchange digital content in its native format, enabling recording, storage, and playback options across a connected system, with no need for a separate Ethernet cable.
- Home entertainment networking – The HDMI Ethernet Channel accommodates current and future IP-based networking solutions for consumer electronics, such as UPnP, LiquidHD, and DLNA. HDMI with Ethernet is the ideal one-cable solution for connecting devices in these advanced home-networking environments.
What network protocols are supported over the HDMI Ethernet Channel?
The HDMI Ethernet Channel feature supports any networking protocol that can run over an existing Ethernet connection, including TCP/IP, UPnP, DLNA, LiquidHD, and so forth.
What is the maximum available bandwidth of the HDMI Ethernet Channel?
Up to 100 Mb/sec of bi-directional (full-duplex) bandwidth is available over the HDMI Ethernet Channel.
Will devices connected via the HDMI Ethernet Channel be able to share an Internet connection?
Yes. Provided there is a routing device somewhere in the network – either a stand-alone router or a device with integral router functionality – the HDMI Ethernet Channel will enable linked devices to share an Internet connection.
Will content distribution and recording be possible in a system connected via the HDMI Ethernet Channel?
Yes. The HDMI Ethernet Channel allows connected devices to share digital content in its native format. For instance, if it is protected by HDCP encryption, it will stay in its encrypted format, and can only be accessed if all the devices in the system are HDCP-compliant. Unprotected content, such as digital HD broadcast programming or user-generated HD video, will of course be free of any content protection.
Will I need a new cable to support HDMI Ethernet Channel functionality?
Yes. The HDMI Ethernet Channel feature will require a new type of cable, either a Standard HDMI Cable with Ethernet or a High-Speed HDMI Cable with Ethernet, depending on the maximum resolution to be supported.
Audio Return Channel
What will I be able to do with an Audio Return Channel -enabled device?
If your HDTV has a built-in tuner, DVD player, or other digital content source, the Audio Return Channel allows the TV to send audio data “upstream” to your A/V receiver, eliminating the need for a separate audio cable in this type of configuration. Audio Return Channel-enabled TVs can either send or receive audio via the HDMI link, giving you greater flexibility in how you set up your home theater equipment and making a separate upstream audio link unnecessary.
Which audio formats are supported over the Audio Return Channel?
The Audio Return Channel supports all the same audio formats that can be sent through a traditional S/PDIF audio connection, including Dolby Digital, DTS, and PCM audio.
Is the HDMI LipSync feature compatible with the Audio Return Channel?
Yes. Whether the TV is sending audio to the sound system or vice-versa, devices featuring LipSync functionality (introduced in HDMI 1.3) will be able to track and correct for any processor lags, and adjust the delivery of audio and video so that the two signals stay in sync.
Will I need a new cable to support Audio Return Channel functionality?
No. Audio Return Channel -enabled devices can be connected via the existing categories of HDMI cables.
3D
Which 3D video formats are contained in HDMI 1.4?
The HDMI 1.4 specification includes information on a wide range of 3D display formats at up to 1080p resolution, including:
- field alternative
- frame alternative
- line alternative
- side-by-side half
- side-by-side full
- L + depth
- L + depth + graphics + graphics depth
What kind of cable will I need to use for 3D?
3D video requires substantial data throughput, so you’ll want to use a High Speed HDMI cable (with or without Ethernet).
Are there any 3D displays available today? What about 3D content?
A number of displays on the market are already 3D capable, including many DLP models. Likewise, there are already some content sources, such as gaming consoles that are 3D-capable. The 3D support introduced in HDMI 1.4 fills an important role by providing an input/output connection that can handle 3D content, and this could help launch consumer 3D video into the mainstream.
Support for 4K format
What does 4K refer to?
4K is a term used to describe displays with resolutions that are essentially four times that of a 1080p device – or roughly 4,000 lines wide by 2,000 lines high. The HDMI 1.4 specification supports multiple 4K formats:
- 3840 pixels wide by 2160 pixels high @ 24Hz | 25Hz | 30Hz
- 4096 pixels wide by 2160 pixels high @ 24Hz
What kind of cable will I need to use for a 4K display?
A High Speed HDMI Cable (with or without Ethernet).
Are there any 4K displays available today? What about 4K content?
The first 4K displays were showcased at the 2009 Consumer Electronics Show. We expect them to be more widely available by the end of 2009, and we hope to see 4K source devices, such as up-scaling Blu-ray Disc players, introduced in roughly the same time frame.
Support for sYCC601, Adobe®RGB, and Adobe®YCC601
What do these color spaces refer to?
These are color formats used in many digital still cameras, providing an extended range of available colors that is wider than what’s available in the traditional RGB color model. By providing native support for these color spaces, HDMI 1.4 enables HDTV manufacturers to deliver better and more accurate color to users when they view their digital photos.
What exactly is a color space?
A color space, also known as a color gamut or color model, defines the total palette of colors available to the display. The traditional RGB color space, developed in the days of analog broadcast TV, delivers a relatively limited subset of what the human eye can actually perceive. Extended color spaces like sYCC601, Adobe® RGB, and Adobe® YCC601 define a broader palette of colors that is closer to the full visible spectrum.
Does this require a new cable?
No. Support for these extended color spaces is compatible with the existing categories of HDMI cables.
What are the new cables that have been introduced as part of HDMI 1.4?
HDMI Ethernet Channel functionality adds a new data channel, so new cables are required to support Ethernet connectivity. These two new cable types are Standard HDMI with Ethernet and High Speed HDMI with Ethernet, with the former supporting resolutions up to 1080i/720p, and the latter built for resolutions of 1080p or higher. Both cable types support a full-duplex 100 Mb/sec Ethernet connection.
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