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Core Video
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<h2 id="overview">Overview</h2> <p>Core Video provides both a buffering model and a playback synchronization solution within its processing pipeline. A video source provides a decompressed data stream to be rendered as images within a visual context in <a href="/facts/Quartz_2D/hGTBq5eR">Quartz 2D</a>. Core Video can be thought of as the link between this video source and its display context. Rendered images can be further processed by <a href="/facts/Core_Image/ar5faNSS">Core Image</a> before being composed into a final scene with <a href="/facts/Quartz_Compositor/etoHysmD">Quartz Compositor</a>. As part of the composition process, Core Video maintains a <i>frame buffer</i>, keeping a pool of rendered, composed frames ready for playback. To ensure smooth playback, Core Video uses a high-priority thread to maintain its frame buffer. This <i>display link</i> runs independently from the application which invokes video playback, and it compensates for different display refresh rates and latency.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> </p><p>Because QuickTime 7 employed Core Video, it was the first version of QuickTime to implement the rendering capability of Quartz. Previous versions of QuickTime used <a href="/facts/QuickDraw/a3QlTctp">QuickDraw</a> for rendering. Although Core Video typically interacts with QuickTime, it can interact with any video source.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> </p><p>Core Video benefits from graphics processor (GPU) rendering and composition provided by Quartz GL, Core Image, and <a href="/facts/Quartz_Extreme/etoHysmD">Quartz Extreme</a>, since final playback is composed on an OpenGL surface.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> </p> <h2 id="history">History</h2> <p>Although Core Video was introduced with the release of <a href="/facts/Mac_OS_X_v10.4/q6vKCpvq">Mac OS X v10.4</a>, it is included in the installation of QuickTime 7 on Mac OS X; thus, Core Video is available for Mac OS X 10.3.9 with QuickTime 7 installed as well.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> </p><p>In Mac OS X 10.4, Core Video is implemented as part of the QuartzCore framework; in Mac OS X 10.5 and later, it resides in its own framework.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> </p> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>"Mac Dev Center - Core Video Programming Guide - Introduction to Core Video Programming Guide". Retrieved September 24, 2009. <a href="https://developer.apple.com/mac/library/documentation/GraphicsImaging/Conceptual/CoreVideo/CVProg_Intro/CVProg_Intro.html" target="_blank">https://developer.apple.com/mac/library/documentation/GraphicsImaging/Conceptual/CoreVideo/CVProg_Intro/CVProg_Intro.html</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>"Mac Dev Center - Core Video Programming Guide - Core Video Concepts". Retrieved September 24, 2009. <a href="https://developer.apple.com/mac/library/documentation/GraphicsImaging/Conceptual/CoreVideo/CVProg_Concepts/CVProg_Concepts.html#//apple_ref/doc/uid/TP40001536-CH202-BABJDFHJ" target="_blank">https://developer.apple.com/mac/library/documentation/GraphicsImaging/Conceptual/CoreVideo/CVProg_Concepts/CVProg_Concepts.html#//apple_ref/doc/uid/TP40001536-CH202-BABJDFHJ</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>"Mac Dev Center - Core Video Programming Guide - Introduction to Core Video Programming Guide". Retrieved September 24, 2009. <a href="https://developer.apple.com/mac/library/documentation/GraphicsImaging/Conceptual/CoreVideo/CVProg_Intro/CVProg_Intro.html" target="_blank">https://developer.apple.com/mac/library/documentation/GraphicsImaging/Conceptual/CoreVideo/CVProg_Intro/CVProg_Intro.html</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>"Mac Dev Center - Core Video Programming Guide - Introduction to Core Video Programming Guide". Retrieved September 24, 2009. <a href="https://developer.apple.com/mac/library/documentation/GraphicsImaging/Conceptual/CoreVideo/CVProg_Intro/CVProg_Intro.html" target="_blank">https://developer.apple.com/mac/library/documentation/GraphicsImaging/Conceptual/CoreVideo/CVProg_Intro/CVProg_Intro.html</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>"Mac Dev Center - Core Video Programming Guide - Introduction to Core Video Programming Guide". Retrieved September 24, 2009. <a href="https://developer.apple.com/mac/library/documentation/GraphicsImaging/Conceptual/CoreVideo/CVProg_Intro/CVProg_Intro.html" target="_blank">https://developer.apple.com/mac/library/documentation/GraphicsImaging/Conceptual/CoreVideo/CVProg_Intro/CVProg_Intro.html</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>"Mac Dev Center - Mac OS X Technology Overview - Graphics and Multimedia Technologies". Retrieved September 24, 2009. <a href="https://developer.apple.com/mac/library/documentation/MacOSX/Conceptual/OSX_Technology_Overview/GraphicsTechnologies/GraphicsTechnologies.html#//apple_ref/doc/uid/TP40001067-CH273-SW21" target="_blank">https://developer.apple.com/mac/library/documentation/MacOSX/Conceptual/OSX_Technology_Overview/GraphicsTechnologies/GraphicsTechnologies.html#//apple_ref/doc/uid/TP40001067-CH273-SW21</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> </ol>