Analog to Digital Conversion (or Converter). Also referred to as digitization or quantization. The conversion of analog signals into digital data, normally for subsequent use in digital equipment. For TV, samples of audio and video are taken, the accuracy of the process depending on both the sampling frequency and the resolution of the analog amplitude information: how many bits are used to describe the analog levels. For TV pictures with modern cameras 14 bits or higher is normally used behind the image sensor; for sound, 16, 20 or 24 bits are common. The ITU-R BT.601 standard defines the sampling of SD video components based on 13.5 MHz, and AES/EBU defines sampling of 44.1 (used for CDs) and 48 kHz for audio. For pictures the samples are called pixels, which contain data for brightness and color. HD and UHD video formats use higher sampling rates and generally more bit depth.