Similarly, for image and video files, bit depth is used to determine the resolution of a picture. The higher the bit depth — 24 bit versus 16 bit, for example — the better the image.
Bit Depth vs. Bit Rate
Bit depth is often confused with bit rate, but they are different. Bit rate, which is measured in kilobits per second, is the data throughput per second when sound is played back, not the resolution of each discrete sample that makes up the audio waveform. Bit depth is sometimes referred to as the sample format or audio resolution.
Bit Depth and Sound Quality
The unit of measure for bit depth is binary digits (bits); for every 1-bit increase, the accuracy doubles. The bit range is an important integer that determines how good a recording sounds. If the bit depth is too low, the recording is not accurate, and a lot of quiet sounds are lost. MP3s stored in your music library that have been converted from analog audio to digital audio signals using pulse code modulation (PCM) with a high bit depth contain a wider spectrum of frequencies than ones encoded with low bit depths. The high-bit-depth recordings are far more accurate on playback, particularly in areas of songs that contain quiet harmonics. Using too low a bit depth can lead to lost frequencies and low-quality recordings. Bit depth is only relevant in the scope of a PCM signal. Lossy compression audio formats do not have bit depths.
Bit Depth and Dynamic Range
Having the right bit depth is a critical aspect to consider to reduce the amount of background noise. Every recording has a degree of signal interference called the noise floor, which is kept to a minimum with a sufficiently high bit depth. This phenomenon occurs because the dynamic range — the difference between the loudest and quietest sounds — is much higher than the noise floor, allowing the difference to keep noise to a minimum. Bit depth also determines how loud a recording can be. For every 1-bit increase, the dynamic range increases by about 6 decibels. Audio CD formats use a bit depth of 16, which equates to 96 dB of dynamic range. If DVD or Blu-ray is used, the sound quality is higher because the bit depth is 24, which gives 144 dB of dynamic range.
