Pulse-code modulation: Difference between revisions

Revision as of 13:05, 29 January 2023

Revision as of 20:04, 25 February 2023

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| screenshot =

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| extension = .L16, .WAV, .AIFF, .AU, .PCM<ref name="rfc2586">{{cite documentjournal|first1=Harald Tveit |last1=Alvestrand |last2=Salsman |first2=James |url=http://tools.ietf.org/html/rfc2586 |title=RFC 2586 – The Audio/L16 MIME content type |date=May 1999 |publisher=The Internet Society |doi=10.17487/RFC2586 |access-date=2010-03-16}}</ref>

| mime = audio/L16, audio/L8,<ref name="rfc4856">{{cite documentjournal|first=S. |last=Casner |url=http://tools.ietf.org/html/rfc4856#page-17 |title=RFC 4856 – Media Type Registration of Payload Formats in the RTP Profile for Audio and Video Conferences – Registration of Media Type audio/L8 |date=March 2007 |publisher=The IETF Trust |doi=10.17487/RFC4856 |access-date=2010-03-16}}</ref> audio/L20, audio/L24<ref name="rfc3190">{{cite documentjournal |last1=Bormann |first1=C. |last2=Casner |first2=S. |last3=Kobayashi |first3=K. |last4=Ogawa |first4=A.

|url=http://tools.ietf.org/html/rfc3190 |title=RFC 3190 – RTP Payload Format for 12-bit DAT Audio and 20- and 24-bit Linear Sampled Audio |date=January 2002 |publisher=The Internet Society |doi=10.17487/RFC3190 |access-date=2010-03-16}}</ref><ref>{{cite web |url=https://www.iana.org/assignments/media-types/audio/ |title=Audio Media Types |publisher=Internet Assigned Numbers Authority |access-date=2010-03-16}}</ref>

| type code = "AIFF" for L16,<ref name="rfc2586" /> none<ref name="rfc3190" />

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| open = Yes

| free = Yes<ref name="LOC_LPCM">{{cite web |title=Linear Pulse Code Modulated Audio (LPCM) |date=April 19, 2022 |url=https://www.loc.gov/preservation/digital/formats/fdd/fdd000011.shtml |publisher=[[Library of Congress]] |access-date=2022-09-05}}</ref>

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==Standard sampling precision and rates==

Common sample depths for LPCM are 8, 16, 20 or 24 bits per [[sample (signal)|sample]].<ref name="rfc2586" /><ref name="rfc4856" /><ref name="rfc3190" /><ref>{{cite documentjournal |url=http://tools.ietf.org/html/rfc3108#page-62 |title=RFC 3108 – Conventions for the use of the Session Description Protocol (SDP) for ATM Bearer Connections |date=May 2001 |access-date=2010-03-16|last1=Mostafa |first1=Mohamed |last2=Kumar |first2=Rajesh |doi=10.17487/RFC3108 }}</ref>

LPCM encodes a single sound channel. Support for multichannel audio depends on file format and relies on synchronization of multiple LPCM streams.<ref name=LOC_LPCM/><ref>{{Cite web|publisher=Library of Congress |url=https://www.loc.gov/preservation/digital/formats/fdd/fdd000016.shtml |title=PCM, Pulse Code Modulated Audio |date=April 6, 2022 |access-date=2022-09-05}}</ref> While two channels (stereo) is the most common format, systems can support up to 8 audio channels (7.1 surround)<ref name="rfc4856"/><ref name="rfc3190"/> or more.

Common sampling frequencies are 48 [[hertz|kHz]] as used with [[DVD]] format videos, or 44.1&nbsp;kHz as used in CDs. Sampling frequencies of 96&nbsp;kHz or 192&nbsp;kHz can be used on some equipment, but the benefits have been debated.<ref>{{Cite web|last=Christopher|first=Montgometry|title=24/192 Music Downloads, and why they do not make sense|url=http://people.xiph.org/~xiphmont/demo/neil-young.html|url-status=dead|archive-url=https://web.archive.org/web/20140906115306/http://people.xiph.org/~xiphmont/demo/neil-young.html|archive-date=2014-09-06|access-date=2013-03-16|publisher=Chris "Monty" Montgomery}}</ref>