Editing MPEG-1 Audio Layer II (section)

==Technical specifications==
MPEG-1 Audio Layer II is defined in ISO/IEC 11172-3 (MPEG-1 Part 3)

*[[Sampling rate]]s: 32, 44.1 and 48&nbsp;kHz
*[[Bit rate]]s: 32, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320 and 384&nbsp;kbit/s

An extension has been provided in MPEG-2 Audio Layer II and is defined in ISO/IEC 13818-3 (MPEG-2 Part 3)<ref name="mpeg-2-layer-1-2">{{cite web | url=http://mpeg.chiariglione.org/technologies/mpeg-2/mp02-aud/index.htm | title=MPEG-2 Audio Layer I/II | author=Werner Oomen, Leon van de Kerkhof | publisher=chiariglione.org | access-date=2009-12-29}}</ref><ref name="mpeg-audio-frame-header">{{cite web |author=Predrag Supurovic |url=https://www.datavoyage.com/mpgscript/mpeghdr.htm |title=MPEG Audio Frame Header |date=September 1998 |access-date=2009-07-11}}</ref>

*Additional sampling rates: 16, 22.05 and 24&nbsp;kHz
*Additional bit rates: 8, 16, 24, 40 and 144&nbsp;kbit/s
*[[MPEG Multichannel|Multichannel support]] - up to 5 full range audio channels and an LFE-channel (Low Frequency Enhancement channel)

The format is based on successive digital frames of 1152 sampling intervals with four possible formats:
* mono format
* stereo format
* intensity encoded joint stereo format (stereo irrelevance)
* dual channel (uncorrelated) format

=== Variable bit rate ===

MPEG audio may have [[variable bit rate]] (VBR), but it is not widely supported. Layer II can use a method called bit rate switching. Each frame may be created with a different bit rate.<ref name="mpeg-audio-frame-header" /><ref>ISO MPEG Audio Subgroup, [http://mpeg.chiariglione.org/faq/mp1-aud/mp1-aud.htm#15 MPEG Audio FAQ Version 9, MPEG-1 and MPEG-2 BC], retrieved on 2009-07-11.</ref>
According to ISO/IEC 11172-3:1993, Section 2.4.2.3: To provide the smallest possible delay and complexity, the (MPEG audio) decoder is not required to support a continuously variable bit rate when in layer I or II.<ref>[http://www.twolame.org/doc/vbr.html TwoLAME: MPEG Audio Layer II VBR], retrieved on 2009-07-11.</ref>

=== MPEG-2 Audio Layer II ===
While the term MP2 and [[filename extension]] <code>.mp2</code> usually refer MPEG-1 Audio Layer II data, it can also refer to MPEG-2 Audio Layer II, a mostly backward compatible extension which adds support for [[Surround sound|multichannel audio]], [[variable bit rate]] encoding, and additional sampling rates, defined in ISO/IEC 13818-3 as part of [[MPEG-2]] standards.