How to convert HDMI to VGA or VGA to HDMI
Today's video technology is moving away from analog (VGA) for a digital connection format (HDMI, DVI, DisplayPort). However, there are still situations where you need to change between display technologies, usually due to differing ports on a computer and display. Video signals may be adapted in either direction (HDMI to VGA or VGA to HDMI), but there are certain limitations and expense differences.
VGA to HDMI
In some situations, it may be necessary to send a VGA signal from a computer to an HDMI port on a newer display device. Using a VGA to HDMI Scaler/Converter, like the one shown in the picture above, lets you connect your computer to any device requiring an HDMI connection.
If your computer only has a VGA connection and you have a desktop computer, you may also consider upgrading the video card in the computer.
HDMI to VGA
An HDMI to VGA converter may be a cheaper cable that connects an HDMI signal from a computer to a VGA connection on an older display. Because VGA is an older technology, this option should be avoided unless there is no other alternative.
An HDMI cable can send an audio and video signal over the same cable. However, a VGA cable can only accept a video signal. To get audio and video, purchase a converter with a VGA connector and an audio cable or USB with audio capability.
Signal quality considerations
Whenever you convert one signal to another, the signal of lesser quality always determines the final output quality. For example, VGA is an analog signal (subject to interference and signal loss in transit), whereas HDMI is digital (higher fidelity, no signal loss). As such, the VGA signal will be the limiting factor of the final output signal.
In other words, converting VGA to HDMI will not improve the signal quality of the original output. Similarly, Converting HDMI to VGA will possibly entail a small loss of signal quality.