Glossary of digital audio
# Glossary of digital audio

## A~C

### AAC

    Advanced Audio Coding is a standardized, lossy compression and encoding scheme for digital audio. Designed to be the successor of the MP3 format, AAC generally achieves better sound quality than MP3 at similar bit rates.

### AC-3

    Audio Coding 3 is a 6-channel, audio file format by Dolby Laboratories that usually accompanies DVD viewing. It operates 5 channels for normal range speakers (20 to 20,000 Hz) and the 6th channel reserved for low-frequency (20 to 120 Hz) sub-woofer operation. AC3 increases fidelity over its previous surround sound standard, Pro-logic, with independent tracks for each of the 6 speakers, a 16-bit depth at 48 kHz sampling rate with a maximum bit rate of 640 kbit/s.

### AIFF

    Audio Interchange File Format is an audio file format standard used for storing sound data for personal computers and other electronic audio devices. The format was developed by Apple Computer.

### ALAC

    Apple Lossless Audio Codec is an audio codec developed by Apple Inc. for lossless data compression of digital music.

### Audio bit depth

    Bit depth or sample resolution is the number of bits of information recorded for each sample. Bit depth directly corresponds to the resolution of each sample in a set of digital audio data. Common examples of bit depth include CD quality audio, which is recorded at 16 bits, SACD with effective 20-bit resolution, and DVD-Audio, which can support up to 24-bit audio.

### Bit rate

    Represents the amount of information, or detail, that is stored per unit of time of a recording. Common examples of bit rates include MP3 which is recorded at 128–320 kbits/s, CD quality audio (LPCM) which is recorded at 1,411.2 kbit/s, SACD (DSD) which is recorded at 5,644.8 kbit/s, and DVD-Audio (MLP), which is recorded at 18,000 kbit/s.

### CD

    Compact Disc is a 16-bit, 44.1 kHz system, giving a frequency response of 5 to 22,000 Hz and 96 dB dynamic range.

## F–Z

### FLAC

    Free Lossless Audio Codec is a codec (compressor-decompressor) which allows digital audio to be losslessly compressed such that file size is reduced without any information being lost.

### LPCM

    Linear PCM is Pulse-code modulation (PCM) with linear quantization.

### MKV

    Matroska Multimedia Container is an open standard free container format, a file format that can hold an unlimited number of video, audio, picture, or subtitle tracks in one file.

### MLP

    Meridian Lossless Packing, also known as Packed PCM (PPCM), is a proprietary lossless compression technique for compressing PCM audio data developed by Meridian Audio, Ltd. MLP is the standard lossless compression method for DVD-Audio content (often advertised with the Advanced Resolution logo) and typically provides about 1.5:1 compression on most music material. All DVD-Audio players are equipped with MLP decoding, while its use on the discs themselves is at their producers' discretion. To store 5.1 tracks in 88.2 kHz / 20-bit, 88.2 kHz / 24-bit, 96 kHz / 20-bit or 96 kHz / 24-bit on a DVD disc, the use of MLP compression is mandatory.

### MP3

    MPEG-1 or MPEG-2 Audio Layer III is a patented encoding format for digital audio which uses a form of lossy data compression.

### PCM

    Pulse-code modulation is a method used to digitally represent sampled analog signals. It is the standard method of storing audio in computers and various Blu-ray, DVD and Compact Disc formats. PCM supports bit rates up to 1,534 kbit/s, sampling rates up to 48.0 kHz, and bit depths up to 24 bits.

### Sampling rate

    Sampling rate or sampling frequency is the number of samples per unit of time (usually seconds) taken from a continuous signal to make a discrete signal. Common examples of sampling rates include CD quality audio, which is recorded at 44.1 kHz, SACD which is recorded at 2.8224 MHz and DVD-Audio, which can support 96 kHz and higher.

### SACD

    Super Audio CD is a format capable of delivering a dynamic range of 120 dB from 20 to 20 kHz and an extended frequency response up to 100 kHz, although most currently available players list an upper limit of 80–90 kHz and 20 kHz is the upper limit of human hearing.

### WAV

    Waveform Audio File Format is a Microsoft and IBM audio file format standard for storing an audio bitstream on PCs.
