Both component video and HDMI are video standards of high quality interface with varying resolution. HDMI stands for High Definition Multimedia Interface. It is one of the latest forms of video standards and delivers digital high definition content through a single cable. The technology is a product of seven companies who were looking for a way to transfer digital data without the use of many cables and without compromising the picture quality. The companies are Hitachi, Panasonic, Sony, Toshiba, Philips, Thomson and Silicon Image. It is a follow up to earlier interface versions like composite video, S-video and component video.
The HDMI makes use of a plug and cable, which is more like a USB cable. The plug has 19 pins and is used to connect high definition visual devices and high resolution multi channel devices. This includes HD DVR, HDTV, HD camcorders, home theatres, Blue-ray players, etc. The 19 pins plug is the standard number, although some later models have 28 pins. Through the HDMI, HD video is transmitted uncompressed and this removes the need for two conversions of the content (from digital to analogue and then back to digital again). This ensures there is no loss of image quality and content. HDMI has an impressive bandwidth of 5 gigabits per second, which is more than the required amount needed to transmit high quality video and audio content. It has 8 audio channels, all supported with one cable, and can also support high resolution surround, like Dolby True HD, DTs and HD Master.
Composite video, on the other hand, transmits its content in analogue format. This is the major difference between the two methods. Composite video is an earlier technology and only supports video. For audio transmission, audio cables will be needed. It transmits video through three signals. The first signal is called the luminance signal and is called the Y component. This signal carries the brightness or the black and white aspect of the content. The other two signals are known as the color difference signals. These indicate how much blue and red there is in the luminance. The blue component is the B-Y while the red component is the R-Y. The two provide the green component.
Although the quality of composite video is almost the same as that of HDMI with very little noticeable difference, the fact that component video uses the analogue format compromises the quality. This is because the video has to undergo two conversions. Its inability to transmit audio content also gives rise to the need for additional audio cables.