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The Ins and Outs of HDMI
The essential connection for high-definition home theater
Today's high-definition home theaters run on digital audio and video, and HDMI™ is the connection of choice. That's because HDMI (High-Definition Multimedia Interface) delivers crystal-clear digital video and audio via a single cable, dramatically simplifying cabling and helping A/V fans enjoy the best possible home theater experience.
In this article, we'll explain what HDMI is and how it differs from conventional analog connections, and include some quick tips on choosing HDMI cables. You'll also learn what the exact differences are among the different versions of HDMI, including the recently announced HDMI 2.0, and what kind of HDMI cables you need for a 4K TV. And finally, we'll look at some real-world HDMI hookup issues along with solutions and workarounds.
HDMI: The "king" of high-quality connections
HDMI's pure-digital interface is the best way to connect high-resolution components — Blu-ray players, the PlayStation® 3 and Xbox 360™ game consoles, and HD-capable satellite and cable TV set-top boxes — to HDMI-equipped high-definition TVs and home theater receivers.
These days, HDMI is often the only way to make an HD-capable connection. Although most TVs still have a component input, it has virtually disappeared on Blu-ray players. Equipment manufacturers have been required to limit the resolution of component video outputs on HD players and boxes to standard-definition (480i). And for a few years now disc makers have have the option of inserting a "digital flag" into a Blu-ray disc that will limit component video resolution to 480i. So if you like high-definition pictures — and who doesn't? — you'll definitely want HDMI connections on your gear.
|HDMI is the connection of choice for high-definition, since it can carry full 1080p video, as well as multichannel audio. It's also the only way to get 3D video signals to your 3D TV.|
Single-cable convenience, plus so much more
The ability to send high-definition video and multichannel audio over a single cable is unique to HDMI, but this interface offers other big advantages.
- Superb picture and sound quality: HDMI connections keep audio and video signals in the digital language of 1s and 0s, eliminating the compromised picture and sound quality caused by digital-to-analog conversions and re-conversions. HDMI supports video resolutions up to 1080p, which is key for 1080p-capable HDTVs and Blu-ray players. (A few TVs will accept 1080p signals via component video, which is useful for gamers since both the PS3 and Xbox 360 can output 1080p over component video.) And HDMI's sound capability now supports up to 8 channels of super-high-quality 24-bit 192kHz audio.
- Ability to carry 3D video: HDMI is the only connection that can carry 3D video signals from components like a 3D Blu-ray player to your 3D TV.
- More than just audio and video: A standard HDMI connector has 19 pins, which carry not only audio and video data, but also 2-way control and identification information, and even low-voltage power. The most recent HDMI cables, labeled "1.4", can also provide an Internet connection between compatible devices.
Industrial-strength copy protection: This probably seems like more of a benefit for content owners like movie studios than for consumers, but it directly affects the quantity and quality of what we can watch — now, and in the coming years. HDMI's wide adoption is due in large part to Hollywood's demands for ever-stronger copy protection measures to prevent piracy. HDCP (High-bandwidth Digital Content Protection) is present on virtually all HDMI-equipped devices even though it's not officially part of the HDMI spec. Without HDCP, both the quantity and quality of high-def content available to consumers would almost certainly be more limited than it is.
Quick tips for choosing HDMI cables
Some components include an HDMI cable in the box, but most don't, so plan on buying one to connect your gear for the best picture and sound. You won't see dramatic differences in picture quality among HDMI cables. Unlike analog video transmission, which can display varying degrees of picture quality, digital video transmission typically delivers a clean, clear picture or no picture at all, although we've occasionally seen picture "sparkles" due to a less-than-flawless HDMI connection.
You'll still want to choose a high-quality HDMI cable, especially for longer lengths or in-wall installations. Different cables use different materials and construction techniques, and some are rated by the manufacturer to maintain maximum signal quality over longer cable lengths. Some users have encountered interoperability issues when making HDMI connections, but these are almost never the fault of the cable itself.
TVs these days often have three or four HDMI inputs to accommodate all your high-def gear. The TV in the illustration above includes three on its back panel and one on its side.
An evolving standard
HDMI is the accepted universal connector for digital home entertainment. The standard continues to evolve to meet the needs of high-performance home theater equipment. All versions of HDMI are backward compatible with previous versions, as well as with DVI with the use of an adapter (however, a DVI connection passes video only, not audio). Part of the built-in intelligence of HDMI enables it to automatically send the highest quality video and audio formats that are mutually supported. In other words, if you connect two devices, one with HDMI version 1.3 and the other with 1.4, the system will be limited to the 1.3 feature set.
Although you'll often see the HDMI version listed as part of a component's specifications, it's probably best not to pay much attention to it. For specific details about a particular component's audio and video capabilities, you're better off focusing on the component's feature list. A product's HDMI version by itself doesn't mean that all the latest features have been implemented; it does not guarantee a particular feature set. The reason is that the capabilities listed for each version of HDMI are optional, not mandatory. It's up to each manufacturer to decide which HDMI features to build into its gear.
Do I need to worry about compatibility between HDMI versions?
Only if you're working with components that use the latest HDMI version — currently 1.4, no 2.0-compatible gear is available yet — and want to take advantage of certain features that are new to the latest spec. However, each new HDMI version is backwards compatible with older versions, so your older and newer HDMI-equipped components can generally still work together. So even if you use a 1.2 cable on 1.4 gear, or a 1.4 cable on 1.1 gear, you'll still get a great high-def picture and sound.
So what are the differences between different HDMI versions? Take a look at our summary of HDMI's evolution below:
HDMI 1.0: The original spec called for a single-cable digital audio/video connection with 165MHz bandwidth and a maximum bitrate of 4.9Gbps (enough for 1080p video). Two-channel audio only. Released December, 2002.
HDMI 1.1: Added multichannnel audio support for DVD-Audio (up to 5.1 channels). Released May, 2004.
HDMI 1.2: Added support for multichannel one-bit audio formats like SACD (Super Audio CD). Included support for HDMI connectors on personal computers. Required displays with HDMI 1.2 or later to support future low-voltage devices. Released August, 2005.
HDMI 1.2a: Fully specified the Consumer Electronic Control (CEC) features and command sets for remote control functions. Required cable manufacturers to submit longer cable lengths for additional testing for spec compliance. For a device to pass 1.2a testing, all of its HDMI connectors required inspection and approval by HDMI Licensing, LLC. Released December, 2005.
HDMI 1.3: Increased bandwidth to 340MHz and the maximum bitrate to 10.2 Gbps (plenty for 3D video). Adopted the "Deep Color" standard, which supports 10-bit, 12-bit, and 16-bit color for over one billion possible colors — previous versions were limited to 8-bit. (Note: Because color information is based on three primary colors — red, green and blue — you'll sometimes see 1.3's enhanced color depth described as 30-bit, 36-bit, and 48-bit.) Added support for the "xvYCC" extended-gamut color space standard (also known as x.v.Color), which supports 1.8 times as many colors as existing HDTV signals. (No commercially available video content currently uses Deep Color or x.v.Color.) Added ability to output new lossless compressed digital audio formats (Dolby® TrueHD and DTS-HD Master Audio™) for decoding by a compatible A/V receiver. Incorporated automatic "lip sync" control for perfect audio/video timing (sometimes an issue when audio is sent to a surround receiver or processor and video is delivered directly to the display). Also made available a new mini-connector for use with smaller devices such as digital cameras and camcorders. Released June, 2006.
The 1.3 spec has been recently updated to 1.3a, followed by 1.3b. However, for consumers, there is no difference between versions 1.3, 1.3a or 1.3b. These are minor revisions that relate to manufacturing and testing issues and do not affect features or functionality.
|Considering upgrading to a 4K TV? Any good-quality HDMI cable labeled "high-speed" should be able to carry 4K video signals.. (AudioQuest Chocolate pictured above)|
HDMI 1.4: Added Ethernet capability. If one HDMI 1.4 device is connected to your home network, it can share that connection with other Internet-ready HDMI 1.4 devices via a 1.4 HDMI cable. Note: As of 9/21/13 we are unaware of any components that support Ethernet over HDMI. Also included the capability to send audio from your TV's tuner back to your home theater receiver. Called an "audio return channel," it's ideal for folks who get their high-def programs over the air using an antenna and want to be able to enjoy surround sound with those TV shows. Released May, 2009.
HDMI 2.0: Increased maximum bitrate to 18 Gbps to support new formats such as 4K video (3840 x 2160 pixels) at up to 60 frames per second. (The 1.4 spec also supports 4K video but only up to 30 frames per second.) HDMI 2.0 also supports up to 32 audio channels, as well as dynamic auto lip-sync, plus new extensions to the CEC control set. Released September, 2013.
Will I need a special "4K-compatible" HDMI cable?
No, you won't need to upgrade to "4K-compatible" HDMI cables. Current HDMI cables that are labeled "high speed" should be able to handle the increased bandwidth of 4K video signals.
HDMI connection issues, solutions and workarounds
Different HDMI versions may cause some interoperability issues — for example, you generally won't be able to get HDMI 1.4 features with non-1.4 gear and cables. See our HDMI 1.4 questions below for more details.
Some problems are also caused by a manufacturer's improper or incomplete implementation of the technology. Some incompatibilities in the digital "handshake" of the HDCP copy-protection code still exist between HDMI-connected components, especially when routed through an HDMI-equipped home theater receiver. Whenever problems like these are discovered, the HDMI standards group contacts the manufacturer and requires that the issue be resolved. In some cases, products have been recalled.
Beyond the initial handshake, there are other possibilities for miscommunication between components. At the beginning of the article, I mentioned that HDMI supports two-way communication between a video source and a TV. Part of that digital conversation is known as "EDID" (Extended Display Identification Data), which describes the TV's capabilities to the source component. EDID info typically includes the manufacturer name, product type, screen resolution, and color depth. Thanks to EDID, two devices can not only talk to each other, they'll actually know whom they're talking to. And that makes auto-configuration possible, which simplifies your setup process.
Keeping all that in mind, here are some of the most common HDMI connectivity issues we've heard about from customers, along with possible solutions or workarounds:
Getting HDMI 1.4 features
Can't get Audio Return Channel from TV to receiver
Make sure your TV and home theater receiver are both HDMI 1.4 components, and that they both support the Audio Return Channel. This may surprise you, but most TVs with 1.4-rated HDMI inputs only support Audio Return Channel on one of those inputs. Next, be sure you're using a 1.3 or 1.4 HDMI cable. (It's confusing, but equipment that's 1.3 and below won't support new HDMI 1.4 features; however, HDMI 1.3 cables can support some of them, namely the audio return channel.)
HDMI and 3D TV
|If you want to watch 3D TV, every component in your system needs to be capable of carrying 3D video signals, and they all need to be connected via HDMI.|
When I try to play my 3D Blu-ray movie, my TV's screen goes blank
The problem is likely that one of the components in your system doesn't support 3D video. For example, if you try to play a 3D Blu-ray movie on a TV that can't display 3D, the TV won't know what to do with the signal and the screen will be blank.
The same thing can happen if you're routing your 3D Blu-ray player's video signal through a non-3D home theater receiver. The receiver won't be able to pass 3D video on to your TV, resulting in an empty screen.
Many 3D Blu-ray players require you to choose between 3D and 2D viewing when you load a Blu-ray disc. If you choose 3D, the player switches to 3D mode, and you have a short amount of time to confirm your selection. If you don't confirm, the player assumes you might not be able to see the image, and reverts back to 2D.
When I try to watch a regular 2D movie, my 3D TV's screen goes blank
If your TV is set to display video in 3D only, it may not be able to accept a regular 2D signal. Go into your TV's display menus and select "Auto" (or something similar) &mdash that tells the TV to display any incoming signals, 2D or 3D, rather than only 3D.
Common HDMI "handshake" issues
No picture or sound using HDMI from DVD player to TV
Some video components come from the factory with the HDMI output set to "off." You can switch it to "on" via the player's setup menu, or sometimes by pressing the "HDMI" button on the component's front panel or remote.
No sound when using the HDTV's HDMI input
Most TVs lack built-in decoding for Dolby Digital and DTS surround sound, and can only play 2-channel audio. But many HDMI-equipped video components come from the factory set up to send multichannel audio. Usually, just changing the component's audio setting to "2-channel (PCM)" solves the problem.
No picture when connecting a cable box to an HDTV
This is usually the fault of the cable box, since some local cable providers may not have upgraded their customers' equipment with new firmware or new boxes to make them fully compliant and compatible with HDMI-equipped TVs and A/V receivers. Customers should report problems to their local cable providers. As with most HDMI-related connectivity issues, one effective workaround is to use component video connections and optical or coaxial digital audio connections.
No closed captions displayed when using HDMI connections
Unfortunately, the HDMI spec doesn't include any requirement for carrying closed captioning data. So, if you connect a video component like an HD cable or satellite receiver or DVD/Blu-ray player to your HDTV using HDMI, you won't see conventional closed captions. If you need to view closed captions from your cable or satellite box, use a component video connection — the closed captions will pass through and you'll still enjoy a high-def picture.
A related issue is that many DVDs and Blu-ray discs simply aren't encoded with closed captioning data. However, most discs are encoded with subtitles, which are similar to closed captions, and subtitles are compatible with HDMI. In fact, a growing number of content providers are using a particular type of subtitling called "Subtitling for Deaf and Hard of Hearing," which is optimized for people with hearing disabilities. While not all discs include subtitles, virtually all DVD and Blu-ray players are capable of decoding subtitles if they're present.
Can't get multichannel audio with an A/V receiver connected between the video source and an HDTV
We've mentioned HDMI's intelligent two-way communication between components, but sometimes it actually contributes to hookup problems. Normally, the display tells the source device about its video and audio capabilities. Virtually all TVs are limited to 2-channel audio playback. Since many A/V receivers employ a "repeater" type of HDMI switch, the receiver simply passes the 2-channel information to the source, despite the receiver's multichannel capabilities. So, the player sends only 2-channel audio to the receiver, rather than high-quality surround sound.
One handy workaround would be to simply run a separate optical or coaxial cable for audio. Unfortunately, many HDMI-equipped components are designed to turn off digital audio outputs when the HDMI output is in use. We have found that some models do this and some don't (even from the same brand), and going forward, we expect to see more models switching off their digital audio outputs.
Another receiver-related HDMI sound issue: some older HDMI-equipped receivers aren't designed to pass audio through their HDMI connections — they perform video switching only. To get multichannel audio from these receivers, you need to connect an optical or coaxial digital cable from your video source to the receiver. Only a few entry-level receivers still have this limitation, but it's something to be aware of.