What is meant by codec

Audio codec

A Audio codec (also: audio codec) is a computer program that compresses or decompresses digital audio data using a specified audio format (or streaming audio format).

In certain contexts, the term "audio codec" can also refer to a hardware device or a sound card. In this case the device is meant that encodes an analog audio signal.

The most popular audio codecs include the following.

Audio codecabbreviationdescription
MPEG-1 Layer 3MP3An official compression standard. So MP3 is a compression technique, not a special codec. There are many codecs for MP3.
  • lame offers an encoder that produces very good quality MP3 files. Both transcode and mencoder use lame for audio compression.
  • MP3 codec from the Fraunhofer Society
MPEG-4 Part 3AACCodecs
    • Psytel AAC (predecessor of Nero Digital Audio)
    • FAAC (Open Source AAC Encoder) and FAAD2 (the corresponding decoder)
other MPEG audio codecs
AC3An official audio compression standard. Almost all DVDs contain AC3 encoded audio tracks. There are decoders for both Windows and Linux that work with AC3 audio within AVI files. The advantage is that no recompression is necessary (recompression is always associated with a loss of quality) and that multi-channel sound (Dolby Surround and the like) is retained. The disadvantage

is that AC3 audio takes up more storage space than MP3 encoded audio.

Real audioRA
Windows Media AudioWMA
Ogg VorbisVorbisAn open source audio compression codec. The advantages are a better quality-to-size ratio compared to MP3 and multi-channel support. Unfortunately, Vorbis audio cannot be properly embedded in AVIs.
Free Lossless Audio CodecFLAC

Mplayer

Under Mplayer, the following are the most important audio codecs.

  • MPEG layer 2 and layer 3 (MP3) audio (built-in code, with MMX / SSE / 3DNow! Optimizations)
  • MPEG layer 1 audio (built-in code, with Libavcodec)
  • Windows Media Audio 9 (WMAv3) (with the DMO DLL)
  • AC3 Dolby Audio (built-in code, with MMX / SSE / 3DNow! Optimizations)
  • Ogg Vorbis audio codec (built-in library)
  • RealAudio: DNET (AC3 with low bit rate), Cook, Sipro, Atrac
  • QuickTime: Qualcomm and QDesign audio codecs
  • VIVO Audio (G723, Vivo Siren)
  • Voxware Audio (using the DirectShow DLL)
  • alaw, MSGSM, PCM, and other simple, legacy audio formats

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