Perceptual audio coder

Perceptual audio coder

Perceptual Audio Coder (PAC) is an algorithm, like MPEG's MP3 standard, used to compress digital audio by removing extraneous information not perceived by most people. It is used by Sirius Satellite Radio for their DARS service, and iBiquity initially tested it for their IBOC digital radio upgrade for FM and AM, but chose an MPEG4-derived codec instead.

The PAC originally developed by Elemedia, a subsidiary of Bell Labs, has a flexible format and bitrate. It provides efficient compression of high-quality audio over a variety of formats from 16 kb/s for a monophonic channel to 1024 kb/s for a 5.1 format with four or six auxiliary audio channels, and provisions for an ancillary (fixed rate) and auxiliary (variable rate) side data channel. For stereo audio signals, it is claimed that it provides near compact disc (CD) quality at about 56-64 kb/s, with transparent coding at bit rates approaching 128 kb/sFact|date=February 2007. In the 1993, ISO-MPEG-2 5-channel test, PAC demonstrated the best decoded audio signal quality available from any algorithm at 320 kb/s, far outperforming all algorithms, including the layer-II and layer-III backward compatible algorithms.Fact|date=February 2007

Over the years PAC has evolved considerably. A known software implementation of this codec is CelestialTech's [ AudioLib] . Later, it was considerably improved and renamed to ePAC (enhanced Perceptual Audio Coder) by Lucent. It's available in the [ AudioVeda] music library manager.

The non-capitalized term is used to describe lossy compression codecs that utilize perceptual coding techniques for audio.

Wikimedia Foundation. 2010.

Поможем решить контрольную работу

Look at other dictionaries:

  • Audio compression (data) — For processes which reduce the amount of time it takes to listen to and understand a recording, see time compressed speech. Audio compression is a form of data compression designed to reduce the size of audio files. Audio compression algorithms… …   Wikipedia

  • Advanced Audio Coding — AAC redirects here. For other uses, see AAC (disambiguation). Advanced Audio Codings iTunes standard AAC file icon Filename extension .m4a, .m4b, .m4p, .m4v, .m4r, .3gp, .mp4, .aac Internet media type audio/aac, audio/aacp, au …   Wikipedia

  • Codificacion perceptual — Codificación Audio Perceptual (CAP) en inglés (Perceptual Audio Coding PAC) es un algoritmo como el estándar MP3 de MPEG usado para comprimir audio digital removiendo información extraña no perceptible por la mayoría de la gente. Éste es usado en …   Wikipedia Español

  • MPEG-1/2 Audio Layer 3 — « MP3 » redirige ici. Pour l’album de M. Pokora, voir MP3 (album). Le MPEG 1/2 Audio Layer 3, plus connu sous son abréviation de MP3, est la spécification sonore du standard MPEG 1/MPEG 2, du Moving Picture Experts Group (MPEG). C est… …   Wikipédia en Français

  • Mpeg-1/2 audio layer 3 — Le MPEG 1/2 Audio Layer 3, plus connu sous son abréviation de MP3, est la spécification sonore du standard MPEG 1, du Moving Picture Experts Group (MPEG). C est un algorithme de compression audio (voir aussi codec) capable de réduire… …   Wikipédia en Français

  • DVD-Audio — Type de média Disque optique Codage MLP ou LPCM Capacité jusqu à 8,5 Go Mécanisme de lecture laser semiconducteur à longueur d onde de 640 nm Développé par DVD Forum Utilisé pour …   Wikipédia en Français

  • HD Radio — HD Radio, which originally stood for Hybrid Digital , is the trademark for iBiquity s in band on channel (IBOC) digital radio technology used by AM and FM radio stations to transmit audio and data via a digital signal in conjunction with their… …   Wikipedia

  • Sirius Satellite Radio — Infobox Company company name = Sirius Satellite Radio company company type = Division of Sirius XM Radio company slogan = The Best Radio on Radio foundation = May 17, 1990 (as Satellite CD Radio, Inc.) location = New York City, New York, United… …   Wikipedia

  • EPAC — Enhanced Perceptual Audio Coder (Academic & Science » Electronics) …   Abbreviations dictionary

  • Data compression — Source coding redirects here. For the term in computer programming, see Source code. In computer science and information theory, data compression, source coding or bit rate reduction is the process of encoding information using fewer bits than… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”