What actually is a key determining factor but not the only consideration in quality is the “bitrate.” Bits are the information to be inserted into the pixels and the bitrate is the rate of time at which those bits of information are placed into the pixels. The more information or bits applied to the pixel, the denser the image and the higher the quality should be if all other factors are equal. Think in terms of a printer, the more dots-per-inch, the sharper the image. So when you ask someone what is the video quality requirement and they say 4CIF, ostensibly they have not advised you of any “visual” aspect of the quality.

• The original material may be sampled at different frequencies
• The samples may use different numbers of bits
• The data may be encoded by different schemes
• The information may be digitally compressed by different algorithms
• The information may be digitally compressed to different degrees