What is HDMI High Definition Multi-Media Interface?

- an overview or tutorial defining HDMI, the high definition multimedia interface widely used for home audio and video applications.

The High-Definition Multimedia Interface, HDMI is an interface that is widely used for audiovisual equipment. In recent years HDMI has grown in popularity because it offers much better performance, and as a result many HDMI leads are sold to enable systems such as home television and home theatre systems to be connected together.

The HDMI interface has a far higher specification than previous interconnection systems that were used. As a result HDMI is used for the new High Definition, or HD television systems and Blu-Ray DVD players that are now becoming standard in many countries. The performance of the HDMI interface means that the system is well suited to the very high data rates that now need to be transferred between units within home television, video and theatre systems.

The very high data rates of 5 Gbps (5 Giga bit per second) achievable using HDMI provide more than twice the bandwidth needed to transmit multi-channel audio and video. Accordingly this means that HDMI will be available for many years to come.

HDMI connectors and pin connections

There are four types of connectors defined under the HDMI standards. The pin connections for the majority of HDMI connectors are given below.

Pin number Signal
1 TMDS Date 2+
2 TMDS Data 2 shield
3 TMDS Data 2-
4 TMDS Data 1+
5 TMDS Data 1 shield
6 TMDS Data 1-
7 TMDS Data 0+
8 TMDS Data 0 shield
9 TMDS Data 0-
10 TMDS Clock+
11 TMDS Clock shield
12 TMDS Clock-
13 CEC
14 HEC Data-
15 SCL (Serial Clock for DDC
16 SDA (Serial Data Line for DDC
17 DDC / CEC / HEC Ground
18 +5 V Power (50 mA max)
19 Hot Plug Detect (1.3) / HEC Data+ (1.4)

Pin connections for Type A HDMI connector.