According to market research firm In-Stat, HDMI ports are increasingly being adopted in set-top boxes, DVD equipment, and mobile PCs. The firm asserts that portable electronic devices such as camcorders, digital still cameras, and Portable Media Players (PMPs) will be emerging HDMI categories in the near future. HDMI penetration in PMPs alone is expected to approach 10 percent by 2012.

As HDMI enters the portable market, the need for embedded designs that offer low power and integration in a single chip is escalating rapidly.

Evolving technology for the portable market

HDMI carries video, audio, control signals, and copy protection in a single connector. Utilizing transition minimized differential signaling digital communications technology, standard HDMI connectors can carry video with resolutions up to 1080p and with up to eight separate audio channels for 7.1 surround sound, plus a consumer electronics control channel providing remote control functions.

The standard Type A HDMI connector is physically large, measuring about 14 mm wide, and is targeted for traditional home “receive” applications such as DVD players/recorders; set-top boxes for cable TV, satellite TV, and IPTV; video game consoles; audio/video receivers (tuner/amplifiers); and audio/video processing devices.

In 2006, a smaller Type C HDMI connector (Figure 1) was introduced to address the needs of portable applications. For example, when developing an HD camcorder, it is almost impossible for designers to enable consumers to see the HD signal without first transferring it to a PC or intermediate format. Although most camcorders incorporate analog composite or S-video outputs, these only handle standard definition video. Digital camcorders were the first products to adopt the smaller HDMI connectors.

Digital still cameras have historically included analog as well as digital video outputs. However, as 5 to 10 megapixel imaging has become commonplace, it is illogical to squeeze this fine detail through blurry analog connections. Even camera phones now typically incorporate 3 or 5 megapixel image sensors, producing more detail than can be seen over analog video connections, and 8 megapixel camera phones are not far behind.

While the screens on PMPs and portable game players are often limited to less than standard definition – 320 x 240 is common – many of these devices are capable of storing HD recordings for users to watch later on their HDTVs. Music enthusiasts can use HDMI to provide a digital audio connection to listen to portable MP3 recordings on a stereo system even when there is no video available.

Moving functionality from stand-alone ICs to SoCs

HDMI ICs have been available for several years and have gained wide popularity in HD home theater components. But for portable applications, these ICs are often too bulky and power hungry to fit into small devices such as compact cameras and handsets. As the industry moves rapidly to 40/45 nm, designers need options for HDMI connectivity, especially in mobile applications.

To overcome the size and power limitations of stand-alone ICs, designers are increasingly incorporating HDMI functionality onto SoCs, eliminating the need for a separate IC and delivering significant power, space, and cost savings. Putting HDMI functionality onto SoCs allows HDMI to be added to handsets and other products where it would have previously been impossible.

HDMI IP selection criteria

As designers look for the right HDMI IP (controller plus PHY, see Figure 2) for their specific applications, they should take into account several technical and business considerations.

Many IP providers are experienced in either digital or analog IP. HDMI requires expertise in both, so designers should consider an IP provider with a combination of analog and digital expertise. Designers should also look for a pure-play IP company that is familiar with SoC designers’ needs, a company that creates HDMI transmitter and receiver IP specifically with designers in mind. This contrasts with some IP suppliers who take existing designs for their own chips and repurpose them as IP. There is also a concern when a company’s IP business is secondary to its chip business, given that technology nodes for stand-alone systems are not the same as those for high-volume SoCs. Designers should look for a company solely focused on developing leading IP solutions in the most advanced processes.

On the technical side, one major consideration is IP flexibility. Some HDMI IP solutions require integration of the entire HDMI specification, which supports a wide range of formats, data rates, and features, many of which are not required for specific applications. For example, a digital still camera SoC doesn’t need to include High-bandwidth Digital Content Protection (HDCP) for Hollywood movies. Eliminating HDCP results in fewer gates, saves licensing fees, and offers significant power savings. SoC designers should select IP that lets them leverage a subset of the standard, choosing features specific to their application.

Designers can also realize large area and power savings through direct system bus access for video and audio. Many HDMI systems require conversion to Inter-IC Sound (I2S) and Sony/Philips Digital Interconnect Format (SPDIF) via translators. These conversions, which essentially serialize parallel data on the transmit side and reverse it to receive, consume area and power. Designers should look for IP that eliminates this inefficiency, delivering system bus flexibility with internal register access and Direct Memory Access (DMA).

Important technical features that designers should consider include:

·    Direct system bus slave interface via Advanced Peripheral Bus (APB), Advanced High-performance Bus (AHB), or Open Core Protocol (OCP)

·    DMA audio via AHB or OCP

·    Multiple audio in/out options including I2C, SPDIF, 1-bit audio, and parallel audio

·    Color space conversion (RGB to/from YCbCr 4:4:4 and 4:2:2)

·    Video in/out in all CEA-861-D video modes (up to 1080p at 60 Hz)

·    Optional HDCP encryption/decryption with external ROM interface for key storage

(click graphic to zoom)

Paving the way for future innovation

HDMI offers convenience for consumers. A single HDMI connection replaces five separate connections required for component video and stereo audio.

HDMI is the most prevalent digital video interface found on TVs for good reasons. Unlike compressed forms of digital video transmissions, HDMI’s uncompressed signal requires a minimum amount of signal processing in the TV itself. Thus, HDMI costs TV manufacturers less to implement than systems that require MPEG-4 or H.264 decoding, for example. Additionally, by carrying raw picture information, HDMI assures highest possible picture quality.

By adding a low-power, low-area HDMI interface to their SoC designs for portable applications, designers can liberate the HD picture quality already there, which until now was not viewable on a TV. Incorporating HDMI IP onto an SoC can streamline the process of adding HDMI capability to practically any portable audio, video, or imaging device.

Luis Laranjeira is part of the HDMI Product Development and Solution Group at Synopsys. He previously served as director of embedded peripherals and digital IP within MIPS Technologies Chipidea’s IP Connectivity Solutions Business Unit in Maia, Portugal. He is responsible for embedded peripherals business management, including USB, DigRF, HDMI, and MIPI systems. Luis has a master’s degree in Electrical and Electronic Engineering from the University of Porto, Portugal.

Synopsys
llaranj@synopsys.com
www.synopsys.com