HD is the term used to differentiate the systems that generate, transmit or support HD content (High Definition) with those of standard definition or low definition (SD).

HD resolutions are usually at least 1280 x 720 pixels by taking the ratio "width x height". Being the height, 720 pixels, which make high resolution.

The English acronym "HDMi" refers to "High Definition Multimedia Interface", that is, it corresponds to the initials of high definition multimedia interface.

The HDMi interface allows the transmission of video and audio between different devices, supporting the video resolutions 480i, 480p, 576i, 576p, 720p, 1080i, 1080p, 1440p, 1600p.

Different versions of HDMi

HDMi 1.0
- December 2002.
- Maximum transfer of 4.9 Gbit / s.
- Support up to 165 Mpixels / s in video mode (1080p 60Hz or UXGA) and 8 channels / 192 kHz / 24-bit in audio mode.

HDMi 1.2
- August 2005.
- Added support for One Bit Audio, used in Super Audio CD, up to 8 channels.
- HDMi Type A availability for PC connectors.

HDMi 1.3
- June 2006
- Bandwidth at 340 MHz.
- 10.2 Gbit / s data rate.
- Dolby TrueHD and DTS-HD,

HDMi 1.4
- Send high definition video and audio,
- 3D data and video.
- FullHD to XHD (eXtended High Definition) up to 4096 × 2160 pixels (24 frames per second) or 3840 × 2160 to (30 frames per second).
- Audio return channel that will require fewer cables to have a surround sound system connected to the television.
- Ethernet connection built into the cable itself with speeds of up to 100 Mbit / s.

HDMi 2.0
- September of 2013
- Bandwidth up to 18 Gbit / s
- 4K @ 50/60 (2160p) video
- Up to 32 audio channels for a multi-dimensional immersive experience
- Up to 1536kHz audio frequency for maximum sound fidelity
- Simultaneous delivery of 2 streaming video for multiple users on the same screen
- Audio streaming up to 4 users
- Support Theater Angle 21: 9 radio
- Dynamic synchronization of video and audio in streaming
- CEC command extensions to control multiple devices from a single point.


Types of HDMi

Type A (in image 1): It is the most standard connector used in almost all devices.
Type B (in image 2): It is a very little used connector.
Type C (in image 3): It is a connector widely used in tablets, smartphones and other devices.
Type D (in image 4): It is a connector used in smartphones.
Type E (in image 5): It is a connector used in vehicle connectivity.

The term VGA (Video Graphics Array or Video Graphics Adapter) is a graphics display system for PCs developed by IBM. VGA has become one of the standards for the PC image. In text mode, VGA provides a resolution of 720 by 400 pixels. In graphics mode, the resolution is either 640 by 480 (with 16 colors) or 320 by 200 (with 256 colors). The color palette is 262,144.Unlike earlier graphic standards for PCs - MDA, CGA, EGA and VGA - uses analog signals rather than digital signals. Since its introduction in 1987, several other standards have been developed that offer greater resolution and more colors (SVGA, XGA ...), but VGA remains the denominator used. All personal computers manufactured today still have support VGA, and possibly some other more advanced connection.

NTSC and PAL are the two coding systems for television signals, each other, they are totally incompatible. NTSC is mainly used in the United States, while the PAL system is one that is typically used in Europe. PAL: 720 x 576 pixels and 25 frames per second NTSC: 720 x 480 pixels and 29.9 frames per second.