HDMI
HDMI supports standard, enhanced, or high-definition video, plus multi-channel digital audio on a single cable. It is independent of the various DTV standards such as ATSC, DVB(-T,-S,-C), as these are encapsulations of the MPEG data streams, which are passed off to a decoder, and output as uncompressed video data, which can be high-definition. This video data is then encoded into TMDS for transmission digitally over HDMI. HDMI also includes support for 8-channel uncompressed digital audio. Beginning with version 1.2, HDMI now supports up to 8 channels of one-bit audio. One-bit audio is what is used on Super Audio CDs.
The standard Type A HDMI connector has 19 pins, and a higher resolution version called Type B, has been defined, although it is not yet in common use. Type B has 29 pins, allowing it to carry an expanded video channel for use with high-resolution displays. Type-B is designed to support resolutions higher than 1080p.
TYPE A
Pin Signal Description
      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  control
      14 Reserved  N.C. on device
      15 SCL  DDC clock
16 SDA  DDC data
17 DDC/CEC Ground  
18 +5 V Power  power EDID/DDC
19 Hot Plug Detect  
TYPE B
Pin Signal Description
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 TMDS Data5+  
14 TMDS Data5 Shield  
15 TMDS Data5-  
16 TMDS Data4+  
17 TMDS Data4 Shield  
18 TMDS Data4-  
19 TMDS Data3+  
20 TMDS Data3 Shield  
21 TMDS Data3-  
22 CEC control
23 Reserved (N.C. on device)
24 Reserved (N.C. on device)
25 SCL DDC clock
26 SDA DDC data
27 DDC/CEC Ground  
28 +5V  power EDID/DDC
29 Hot Plug Detect