Digital formats represent analog phenomena or digital constructions through binary code.
Binary code consists of ÓbitsÓ made from a series of digits, each digit being either 0 or 1.
Numerical bit designations (16 bits, 24 bits, etc.) refer to the number of digits used for each bit.
The number of possible values for a bit is limited by the number of distinct variations the digits can construct together. 1 bit can contain 1 of 2 values, while 2 bits can contain any of 4 possible values.
The frequency response, dynamic range and fidelity or quality of digital sound is limited by the bit rate of its format, and its sampling rate.
The sampling rate represents the number of times per second the soundŐs waveform is analyzed (or in the case of digital synthesis, constructed) and converted to a bit of code. The highest frequency that can be sampled is one-half that of the sampling rate.
The number of possible values for each bit are limited by the bit rate.
Audio CDs use a 44.1k sampling rate at 16 bits. DV samples audio at either 48k/16 bit or 32k/12 bit. Professional digital audio systems generally use sampling rates of 48 or 96k and bit rates of 16 or 24 bits.
The fidelity or quality of digital images is likewise limited by an image formatŐs channel structure, bit rate, and resolution.
Resolution is determined by how many discreet sites are assigned in a grid to the image. Each of these sites has a value that is then represented by a bit of code. The sites are commonly referred to as pixels. The more pixels within a given area, the higher the resolution of the photo.
Bit rate determines the possible values for each of those pixels.
RGB images use three independent grayscale channels. At 8 bits per channel, this produces millions of possible color combinations.
YUV images, commonly found in video formats, use one channel for grayscale values and two to represent color values. The U and V channels are often sampled at a reduced resolution to save space and bandwidth, since the eye is more sensitive to light than to color. DV and HDV, for example, samples video at 4:1:1 Đ the color channels are sampled at 1/4 the resolution of the luminance channel.
Digital Video formats also deal with temporal resolution, usually expressed in terms of frame rate and a designation as to whether each frame is interlaced (created from two half-resolution frames occurring at adjacent time units) or progressive (created from a single, full-resolution image).