AC3 (AC-3) audio format:
The AC-3 algorithm (short for Arc Consistency Algorithm #3) is one of a series of algorithms used for the solution of constraint satisfaction problems (or CSP's). It was developed by Alan Mackworth in 1977. The earlier AC algorithms are often considered too inefficient, and many of the later ones are difficult to implement, and so AC-3 is the one most often taught and used in very simple constraint solvers.

Dolby Digital is the common version containing up to six discrete channels of sound. The most elaborate mode in common usage involves five channels for normal-range speakers (20 Hz – 20,000 Hz) (right front, center, left front, right rear and left rear) and one channel (20 Hz – 120 Hz allotted audio) for the subwoofer driven low-frequency effects. Mono and stereo modes are also supported. AC-3 supports audio sample-rates up to 48 kHz. Batman Returns was the first film to use Dolby Digital technology when it premiered in theaters in Summer 1992. The Laserdisc version of Clear and Present Danger featured the first Home theater Dolby Digital mix in 1995.

This codec has several aliases, which are different names for the same codec:
* Dolby Digital
* DD (an abbreviation for Dolby Digital, often combined with channel count; for instance, DD 2.0, DD 5.1)
* AC-3 (Audio Codec 3, Advanced Codec 3, Acoustic Coder 3. These are backronyms. However, Adaptive Transform Acoustic Coding 3, or ATRAC3, is a separate format developed by Sony)
* ATSC A/52 (name of the standard)

AC3(AC-3) converter:ac3 audio converter software
AC3 Converter is a powerful audio converter. Which can batch-convert audio formats AC3,MPC(MusePack),WMA ,MP3, WAV, APE, AAC(used by iTunes),FLAC(lossless compression),MP2,MP4,M4A, OGG,TTA,ofr(OptimFROG),SPX(Speex),Ra(Real audio), and WavePack
from one to another.