Video portables and cameras get HDMI outputs

Doug Bartow, Analog Devices, Inc.

April 13, 2007

Doug Bartow, Analog Devices, Inc.April 13, 2007

The ability to capture high-definition (HD) video in affordable, high-definition camcorders, digital still cameras, and personal media players has created confusion over which display interface is now the best choice. After taking advantage of significant price decreases in LCD-TVs and plasma TVs during 2006, many consumers are interested in upgrading all their video "appliances" to the HD format, so they can enjoy all of their video and images in high definition. While making this transition to high definition with new HD handheld video appliances, it only makes sense to also upgrade to a higher quality interface to connect them to their HD displays.

Several display interfaces are popular with standard definition (SD) video appliances. Commonly found on digital still cameras (DSC) and video camcorders are the analog composite (NTSC, PAL and S-Video) outputs, and sometimes the component (YPbPr) outputs that were used to connect directly to analog CRT-TV displays. IEEE-1394 and USB are digital interfaces that have become popular for connecting video portables to PCs.

Figure 1: HD camcorder block diagram

The HDMI (High-Definition Multimedia Interface), which was developed for connecting HDTVs and DVD players, is a high-bandwidth digital interface that combines audio and video over a single cable. Of all available interface choices, only HDMI offers the bandwidth necessary to support the transfer of uncompressed, pure digital HD audio/video signals between compatible devices.

Until recently, HDMI transmitters were not well suited for battery-powered handheld applications. Designed specifically to meet the requirements of DVD players/recorders, they were too power hungry and physically large for handheld applications. With battery-powered devices, every additional milliwatt is critical because the extra power consumption shortens battery life and adds to the size, weight and cost of the device. "Smaller is beautiful" is the mantra for all handheld device designers, and reducing the size and weight of individual components is an ongoing challenge.

As the availability of in-home HD displays increased, a growing need developed for connecting these good-looking displays with higher quality video and audio interfaces. Price reductions on 6M pixel and greater DSCs, new 1080i HD video camcorders, and personal media players (video iPods) have led to an increase in the number of consumers using these higher quality display sources. The existing analog (component and composite) video and digital (1394 and USB) interfaces require use of compressed digital video formats. The HDMI interface, with its broad acceptance in HDTVs, is the best choice for a higher quality, non-compressed digital interface for these new high-definition handheld devices. HDMI has become the de facto standard for the HD digital interface designed into HDTVs. DVD players/recorders, set-top boxes (STB) for cable TV, and satellite TV and A/V receivers are now available with HDMI interfaces for transferring HD audio and video information to HDTVs. All that was missing were HDMI transmitters that were designed to meet the demanding requirements of battery-powered, handheld devices.

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