HDMI
The High-Definition Multi-media Interface (HDMI) is an industry-supported, uncompressed, all-digital audio/video interface. HDMI provides an interface between any compatible digital audio/video source, such as a set-top box, DVD player, and A/V receiver and a compatible digital audio and/or video monitor, such as a digital television (DTV).
HDMI supports standard, enhanced, or high-definition video, plus multi-channel digital audio on a single cable. It transmits all ATSC HDTV standards and supports 8-channel digital audio, with bandwidth to spare to accommodate future enhancements and requirements.
A high-bandwidth version of the standard 19-pin Type A HDMI connector, called Type B, has been defined, although it is not yet in common use. This has 29 pins, allowing it to carry an expanded video channel for use with high-resolution displays.
Type A HDMI is backwards-compatible with the single-link Digital Visual Interface (DVI) used on computer monitors and graphics cards. This means that a DVI source can drive an HDMI monitor, or vice versa, by means of a suitable adapter or cable, but the audio and remote control features of HDMI will be unavailable. Type B HDMI is similarly backwards-compatible with dual-link DVI.
The HDMI Founders include leading consumer electronics manufacturers Hitachi, Matsushita Electric Industrial (Panasonic), Philips, Sony, Thomson (RCA), Toshiba, and Silicon Image. Digital Content Protection, LLC (a subsidiary of Intel) is providing High-bandwidth Digital Content Protection (HDCP) for HDMI. In addition, HDMI has the support of major motion picture producers Fox, Universal, Warner Bros. and Disney, and system operators DirecTV, EchoStar (Dish Network) as well as CableLabs.
Technical Specifications
TMDS channel
- Carries audio, video and auxiliary data.
- Signalling method: According to DVI 1.0 specification. Single-link (Type A HDMI) or dual-link (Type B HDMI).
- Video pixel rate: 25 MHz to 165 MHz (Type A) or to 330 MHz (Type B).
- Pixel encodings: RGB 4:4:4, YCbCr 4:2:2, YCbCr 4:4:4.
- Audio sample rates: 32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz, 176.4 kHz, 192 kHz.
- Audio channels: up to 8.
DDC channel
- Allows source to interrogate capabilities of sink.
- I²C signalling with 100 kHz clock.
- E-EDID data structure according to EIA/CEA-861B and VESA Enhanced EDID.
Consumer Electronics Control (CEC) channel (optional)
- Used for remote control functions.
- One-wire bidirectional serial bus.
- Defined in HDMI Specification 1.0.
Content Protection
- According to High-Definition Content Protection (HDCP) Specification 1.10.
Connector Detail
Connector example: Molex 500254-1907
Type A Connector Pin Assignment
| Pin | Signal Assignment | Pin | Signal Assignment |
| 1 | TMDS Data2+ | 2 | TMDS Data2 Shield |
| 3 | TMDS Data2– | 4 | TMDS Data1+ |
| 5 | TMDS Data1 Shield | 6 | TMDS Data1– |
| 7 | TMDS Data0+ | 8 | TMDS Data0 Shield |
| 9 | TMDS Data0– | 10 | TMDS Clock+ |
| 11 | TMDS Clock Shield | 12 | TMDS Clock– |
| 13 | CEC | 14 | Reserved (N.C. on device) |
| 15 | SCL | 16 | SDA |
| 17 | DDC/CEC Ground | 18 | +5V Power |
| 19 | Hot Plug Detect |