Let Us Understand The Basic TermsMultimedia-combination of different content forms.

Interface-point of interaction between two systems or work groups.

High definition- refers to video having resolution substantially higher than traditional television systems.

Definition And Need Of HDMIHDMI is a compact audio/video interface for transmitting uncompressed digital data.

HDMI connects digital audio/video sources.

It’s a single cable and user friendly that replaces the maze of cables.

Overview of HDMI High quality sound or vision without compression of a video or audio signal.

HDMI pictures are smoother and sharp. Sound is also crisp and taut, without any distortion.

HDMI works well with fixed-pixel displays such as LCD, plasma or DLP screens and projectors.

A HDMI cable allows to match pixel-by pixel the native resolution of the screen such as 16:9 or 4:3.

HDMI signals are digital in nature. TVs and radios operate on analog signals.

HDMI has some built-in smarts.

Versions of HDMI

HDMI 1.0 - combines digital video signal with 2 channel audio signal.

HDMI 1.1 - transfer Dolby Digital, DTS, and DVD-Audio surround signals,7.1 channels of PCM audio.

HDMI 1.2 - to transfer SACD signals in digital form from a player to a receiver.

HDMI 1.3 - increase the video bandwidth, transfer color depths up to 48-bits, the 1080p resolution in use today.

HDMI VS DVI

HDMI Technology does not incorporates

content security that is called High Definition Content Protection.

That DVI can only support digital video on a single cable.

DVI HDMI technology incorporates

content security that is called High Definition Content Protection.

HDMI can support audio and video on the same cable.

Pin Configurations

Pin Descriptions

TMDS Channel/TMDS Clock

It was developed by Silicon Image.

Transfer huge amounts of data through a shielded cable.

each are capable of transfer rates up to 3.4Gbps a total 10.2Gbps.

Up to 48-bit resolution.

pixel clock for timing the data stream.

DDC channel & EDID chip

determine the audio / visual capabilities .

achieved by reading from an EDID ROM chip.

automatically adjust the video and audio output.

HDCP utilizes the DDC channel to initiate a "handshake“.

CEC-Consumer Electronics Control

One Touch Play.

System Standby.

One Touch Record.

Deck Control.

Tuner Control.

Content Protection - HDCP

by encrypting the digital content being sent from the source to the receivers.

the source and receivers initiate a "handshake" and validate that each device is an authorized one.

exchanges a special key called a Key Selection Vector or KSV.

XOR operation is applied to encrypt each decoded pixel with a 24-bit number.

Hot Plug Detect Signal

high voltage level when the E-EDID is not available for reading.

asserted only when the +5V Power line from the Source is detected.

A Source may use a high voltage level to initiate the reading of E-EDID data.

An HDMI Sink indicate any change of the E-EDID by driving a low voltage level for at least 100 msec.

HDMI Block Diagram

Explanation

follow all of the rules for an HDMI Sink and HDMI Source.

four differential pairs that make up the TMDS data and clock channels.

DDC is used for configuration and status exchange between a single Source and a single Sink.

CEC protocol provides high-level control functions .

HDMI Plugs/connectors

TYPE A -Nineteen pins, with bandwidth to support all SDTV, EDTV, and HDTV modes.

TYPE B - This connector (21.2 mm × 4.45 mm) has 29 pins and can carry double the video bandwidth of Type A.

TYPE C - all positive signals of the differential pairs are swapped with their corresponding shield.

TYPE D - shrinks the connector size to something resembling a micro-USB connector.

Encoder/Decoder

Explanation

TMDS Clock channel constantly runs at the pixel rate of the transmitted video.

each of the three TMDS data channels transmits a 10-bit character.

The input stream to the Source‘s encoding logic will contain video pixel, packet and control data.

These data items are processed in a variety of ways .

are presented to the TMDS encoder as either 2 bits of control data, 4 bits of packet data or 8 bits of video data per TMDS channel.

encodes one of these data types or encodes a Guard Band character on any given clock cycle.

Advantages

Higher Quality.

Intelligence.

Authentication and Encryption.

Deep Colors.

No Compression.

Dolby/DTS.

Disadvantages

Distance Limitations

Switching Delays

Field Termination

Costly

Applications

Blu ray discs/HD DVD players

Personal computers

Wireless HDMI with low-latency, lossless H.264 video codec

Relationship with Display Port