HDMI Audio

HDMI (High Definition Multimedia Interface) was created to provide an interface for transmitting uncompressed digital video. It was adopted as a digital option to long-standing analog video standards such as S-Video, RF coaxial cable, and VGA. The HDMI standard refers to cables implementing HDMI that connect set top boxes, HD DVD players, Blu-ray Disc players, computers, the Xbox 360, and Playstation 3 to other devices such as HD televisions and computer monitors.

What Formats Does HDMI Support?

HMDI is capable of transporting or transferring all uncompressed video formats including up to 8 channels of compressed/uncompressed digital audio in addition to a CEC (Consumer Electronic Control) connection. The CEC is a unique addition to the HDMI standard that permits compatible devices to control each other. More importantly, it lets the consumer use a single remote control for multiple electronic devices. Since HDMI supports all video standards, there is no loss of video quality when converting Digital Visual Interface (DVI) video or ATSC to HDMI. HDMI requires closed caption streams to be decoded as an image in the video prior to being sent over an HDMI cable that limits caption styles that can be shown on HDMI devices.

When Was HDMI Adopted?

Although approved as a standard before 2003, the first HDMI supported products were distributed in 2003. In 2005, the standard became more popular in Europe and other countries, and started to be included on camcorders and digital cameras in 2006. HDMI exceeded DVI in popularity in 2008 and is currently supported on the majority of devices that can display or record digital images/video.

What Does the HDMI Specification Define?

The HDMI specification provides definitions for the mechanical requirements, signals, protocols, and electrical interfaces for supporting devices. As computer and video technology improves, the HDMI standard is revised to support increasingly complex video formats and quality. For example, the original HDMI standard supported a maximum pixel clock rate of 165 MHz which could transfer video displays up to 1920 x 1200 pixels at a 60 Hz rate. The next update of HDMI (1.3) increased the maximum clock rate to 340 MHz and had displays of up to 2560 x1600 resolution on a single link. More recently, HMDI connections support a Type A/C single link or Type B dual link connection.

What Type of Audio Does HDMI Support?

Up to 8 channels of uncompressed audio can be included in an HDMI connection. The sample sizes can range from 16 bit to 24 bit and can currently be sampled at rates of 32 kHz, 44.1 kHz, 88.2 kHz, 96 kHz, 176.4 kHz, and 192 kHz. HDMI also supports Dolby Digital, DTS, and on-bit DSD audio streams. HDMI’s standard release 1.3 increased the quality of digital audio. It can now be transmitted over an HDMI connection by supporting “lossless” compressed audio streams.

What Are the HDMI Connector Types?

There are several types of HDMI connections defined in the original and subsequently released specifications. The Type A and B connections were defined in the original standard and have 19 and 29 pins respectively, with the Type B connection being able to carry twice the bandwidth of a Type A connection. The Type C connector was defined in the HDMI 1.3 spec and is intended for use with portable devices but has a 19 pin connection similar to the Type A connection. The Type D HDMI connector was defined in the HDMI 1.4 specification. It has a 19 pin connector, but has a size equivalent to the Type C connection. The 1.4 spec also defined a special automotive HDMI connection system.

The Future of HDMI

In 2010, HDMI released an update to the 1.4 standard in order to lay the groundwork for supporting 3D video formats. Manufacturers have been quicker to update consumer electronic products with the latest standards of HDMI in order to provide shoppers with the latest choices for video support on personal electronics.