Editing MPEG-1 (section)

===MPEG-2 audio extensions===
The [[MPEG-2]] standard includes several extensions to MPEG-1 Audio.<ref name=audio_tutorial/> These are known as MPEG-2 BC – backwards compatible with MPEG-1 Audio.<ref name="mpeg-audio-faq-bc">{{cite web |url=http://mpeg.chiariglione.org/faq/mp1-aud/mp1-aud.htm |title=MPEG Audio FAQ Version 9 – MPEG-1 and MPEG-2 BC |author=ISO |date=October 1998 |publisher=ISO |access-date=2016-11-11 |url-status=dead |archive-url=https://web.archive.org/web/20100218081343/http://mpeg.chiariglione.org/faq/mp1-aud/mp1-aud.htm |archive-date=2010-02-18 }}</ref><ref name="mpeg-audio">{{cite web |url=http://mpeg.chiariglione.org/faq/audio.htm |title=MPEG Audio FAQ Version 9 - MPEG Audio |author=D. Thom, H. Purnhagen, and the MPEG Audio Subgroup |date=October 1998 |access-date=2016-11-11 |url-status=live |archive-url=https://web.archive.org/web/20110807233226/http://mpeg.chiariglione.org/faq/audio.htm |archive-date=2011-08-07 }}</ref><ref name="mpeg-bc">{{cite web|url=http://www.mpeg.org/MPEG/audio/aac.html |archive-url=https://web.archive.org/web/20070831110756/http://www.mpeg.org/MPEG/audio/aac.html |url-status=dead |archive-date=2007-08-31 |title=AAC |author=MPEG.ORG |access-date=2009-10-28 }}</ref><ref name="iso13818-7-2006-pdf">{{citation |url=http://webstore.iec.ch/preview/info_isoiec13818-7%7Bed4.0%7Den.pdf |title=ISO/IEC 13818-7, Fourth edition, Part 7 – Advanced Audio Coding (AAC) |author=ISO |date=2006-01-15 |access-date=2016-11-11 |url-status=live |archive-url=https://web.archive.org/web/20090306055335/http://webstore.iec.ch/preview/info_isoiec13818-7%7Bed4.0%7Den.pdf |archive-date=2009-03-06 }}</ref> MPEG-2 Audio is defined in ISO/IEC 13818-3.

*[[MPEG Multichannel]] – Backward compatible 5.1-channel [[surround sound]].<ref name=sydney93/>
*[[Sampling rate]]s: 16000, 22050, and 24000&nbsp;Hz
*[[Bitrate]]s: 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144 and 160&nbsp;kbit/s

These sampling rates are exactly half that of those originally defined for MPEG-1 Audio. They were introduced to maintain higher quality sound when encoding audio at lower-bitrates.<ref name=sydney93/> The even-lower bitrates were introduced because tests showed that MPEG-1 Audio could provide higher quality than any existing ({{circa|1994}}) very low bitrate (i.e. [[Speech coding|speech]]) audio codecs.<ref name=singapore94>{{Citation|first=Leonardo |last=Chiariglione |title=Press Release |date=November 11, 1994 |publisher=[[International Organization for Standardization|ISO]]/[[International Electrotechnical Commission|IEC]] |url=http://mpeg.chiariglione.org/meetings/singapore94/singapore_press.htm |archive-url=https://web.archive.org/web/20100808100029/http://mpeg.chiariglione.org/meetings/singapore94/singapore_press.htm |url-status=dead |archive-date=August 8, 2010 |access-date=2008-04-09 }}</ref>