Constant angular velocity

<h2 id="dimensions">Dimensions</h2>

<p>In case of a 12 cm standard diameter disc, data at the outermost edge (6 cm from center) is accessed at 2.4 times the speed of data at the inner edge of the data-containing program area (2.5 cm from center).<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a>
</p><p>For a <a href="/facts/MiniCD/BxSG8aP5">miniature disc</a> with a diameter of 8 cm (radius of 4 cm), the speed ratio of outer to inner data edge is 1.6.
</p><p>This means that, for example, if a disc is accessed at a constant angular velocity of ×24, the equivalent <a href="/facts/Linear_velocity/Q3o1LVDe">linear velocity</a> is ×24 while accessed at the outermost edge of the data area while being ×10 at the innermost data area.
</p>
<h2 id="uses">Uses</h2>

<p><a href="/facts/Gramophone_record/ccuFV9Af">Gramophone records</a> have always used CAV, including <a href="/facts/Capacitance_Electronic_Disc/NSJJq3DI">CEDs</a> which provide video signals.
</p><p>Some high-speed CD and DVD drives can use CAV.[<i>specify</i>] It allows for shorter <a href="/facts/Access_time/Ckb7x4f6">access times</a> because the rotation speed (angular velocity) does not need to be changed when the laser seeks across the disc, similarly to the <a href="/facts/Disk_read-and-write_head/WdpxUpjK">magnetic head</a> of a <a href="/facts/Hard_disk_drive/kekLSGSE">hard disk drive</a>. With a given angular (rotation) speed, the linear speed at the outermost track is nearly 2.4 times as fast as that of the innermost track.
</p><p>CAV was used in the <a href="/facts/LaserDisc/nU4WJhDM">LaserDisc</a> format for interactive titles; it was also used with <a href="/facts/Special_edition/femghLFN">special editions</a> of certain films.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> CAV allowed for perfect still frames, as well as random access to any given frame on a disc. Playing time, however, was 30 minutes on each side (these discs are also known as "standard play"), as opposed to 60 minutes on each side for CLV-based discs ("extended play").
</p><p>CAV is used with the <a href="/facts/Nintendo_optical_disc/Kh5UeX5j">Nintendo GameCube Game disc and Wii Optical disc</a>, the <a href="/facts/Xbox_(console)/2FuQrJeX">original Xbox</a> discs, and Sega's <a href="/facts/GD-ROM/SSqNquk6">GD-ROM</a>.
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<h3>Partial constant angular velocity (P-CAV)</h3>
<p>If the used media (e.g. <a href="/facts/DVD-RAM/BKNMvYT8">DVD-RAM</a> variants) has a linear (writing) speed limitation that can not be attained with physically supported angular (rotation) speeds at the inner edge of the recordable area, the disc writing can start off with a constant angular velocity, until the increasing linear velocity has reached the writing speed limitation of the disc.
</p><p>At that point, the drive transitions into writing with a constant linear velocity.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a>
<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a>
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<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Constant_linear_velocity/UJdUk4rv">Constant linear velocity</a> (CLV)</li>
<li><a href="/facts/Zone_bit_recording/oMB8bRnM">Zone bit recording</a> (ZCAV)</li>
<li><a href="/facts/Optical_storage_media_writing_and_reading_speed/k6zs0rJh">Optical storage media writing and reading speed § Various optical disc formats writing/reading speeds</a></li></ul>

<h2 id="external-links">External links</h2>
<ul><li><a href="http://www.pcguide.com/ref/hdd/geom/tracksZBR-c.html">http://www.pcguide.com/ref/hdd/geom/tracksZBR-c.html</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Christodoulakis, S.; Ford, D. A. (1989). "File organizations and access methods for CLV disks". SIGIR Forum. 23: 152–159. doi:10.1145/75335.75350. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Press, Larry (2003). "Optical storage". Encyclopedia of Computer Science. John Wiley and Sons Ltd.: 1336–1339. ISBN 0470864125. <a href="0470864125" target="_blank">0470864125</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>"FUNDAMENTOS DE HARDWARE. – Page 37 of 45 (graphic)". Archived from the original on 2022-02-23. Retrieved 2020-07-13. <a href="https://web.archive.org/web/20220223102343/https://docplayer.es/74808946-fundamentos-de-hardware.html" target="_blank">https://web.archive.org/web/20220223102343/https://docplayer.es/74808946-fundamentos-de-hardware.html</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
<li id="fn:4"><p>"The Criterion Collection: Ghostbusters". voyagerco.com. Voyager Media Store. Archived from the original on 1997-02-13. Retrieved 2012-04-30. <a href="https://web.archive.org/web/19970213145931/http://www.voyagerco.com/criterion/catalogpage.cgi?ghostbusters" target="_blank">https://web.archive.org/web/19970213145931/http://www.voyagerco.com/criterion/catalogpage.cgi?ghostbusters</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li>
<li id="fn:5"><p>QPxTool glossary: P-CAV (partial constant angular velocity) <a href="https://qpxtool.sourceforge.io/glossar.html#p_cav" target="_blank">https://qpxtool.sourceforge.io/glossar.html#p_cav</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li>
<li id="fn:6"><p>"CDRLabs.com - Samsung SE-208GB Portable 8x DVD Writer - Reviews". CDRLabs. 2014-12-03. Retrieved 9 August 2020. <a href="http://www.cdrlabs.com/reviews/samsung-se-208gb-portable-8x-dvd-writer/print.html" target="_blank">http://www.cdrlabs.com/reviews/samsung-se-208gb-portable-8x-dvd-writer/print.html</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li>
</ol>

Constant angular velocity open-in-new

Constant angular velocity