HDMI

HIGH DEFINITION MULTIMEDIA INTERFACE

INTRODUCTION

It is a connector between high definition devices such as Blu-ray disc, a video game console to a compatible digital audio or video monitor such as digital television.

GENERAL

HDMI encodes the video data into TMDS for transmission digitally over HDMI.

TMDS is a channel which carries video, and/or audio through one of three modes;

1. Video Data Period:The pixel of an active video are

transmitted.2. Data Instant Period:

Audio are transmitted with a series of packets.

3. Control Period:Occurs between video and data

island periods.

Different versions of HDMI have been introduced, from HDMI 1.0 to 1.3. Same cable is being used but there is difference in throughput.

HDMI VS DVI

DVI used for carrying digital video on modern computer monitors and graphic cards. HDMI is backward compatible with DVI and vice versa; but

Audio and remote control features of HDMI will not be available.

Without support of HDCP on display, the signal source, prevent end user from viewing or recording certain restricted contents.

SPECIFICATIONS

The are electrical and mechanical requirements of the cable and connectors.

Connectors:HDMI specifications include three

connectors intended for different markets.

a. Standard type A HDMI connectors has 19 pins with bandwidth to support SDTV, EDTV & HDTV modes.

b. A high resolution type B HDMI 1.0 connector has 29 pin.

which allows to carry an expanded video channel for use with very high resolution displays.

c. A type C mini connector, intended for portable devices but has the same 19 pins.

Cable:HDMI cables are available for

type A to type C. It is used to carry video, audio and devices controlling signals.

TMDS Channel:Carries videos, audios through

three modes;Video Data PeriodData Island PeriodControl Period

CEC Channel:It is optional to implement,

but wiring is necessary, the channelUses a industry standard protocol.Used for remote control functions.

Is a one-wire bidirectional serial bus.Defined in HDMI 1.0, updated in

HDMI 1.2a and again in 1.3a.

VERSIONS

HDMI 1.0: December 2002Single cable digital audio/video

connection, maximum of 4.9 Gbits/sec.HDMI 1.1: May 2004

Added support for DVD audio.HDMI 1.2: August 2005

Added support for one bit Audio, used on super audio CDs, up to 8 channels.

The availability of HDMI type A connector.

HDMI 1.2a: December 2005Fully specifies consumer

electronics control (CEC) features.HDMI 1.3: June 2006

Increased bandwidth to 10.2 Gbits/sec.

Availability of a new mini-connector for devices (type C).

HDMI 1.3a: November 2006Cable modification for type C.Source termination is

recommended.HDMI 1.3b:

Testing specification (happening) released on 26 march 2007.

CABLE LENGTH

No specific cable length. HDMI 1.3 introduces 2 kinds of cables

to reduce the confusion about which cable supports which video format. Category 1:

Standard or HDTV 28, AWG about 5 meter long

Category 2: High speed/greater than HDTV Higher quality, 24 AWG about 12-15 meter.

HDMI & HD OPTICAL MEDIA PLAYER

HD DVD, Blu-ray disc uses Dolby Digital plus, Dolby True HD and DTS-HD master Audio having very high bitrates.

HD DVD, Blu-ray permit “interactive audio”.

CRITICISM

Connector are not robust as previous display connectors. Tripping over a cable plugged into an HDMI port can easily damage the port.

Lack of security mechanism built on connectors and plug are more prone to physical and/ or electrical damage.

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