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光驱一般用倍速表示其传输速率。在制定标准时,把150K字节/秒的传输率定为标准,后来光驱的速率越来越快,就出现了倍速、四倍速直到现在的32倍速、40倍速甚至50倍速(其传输速率为150×50=7500K字节/秒)。以前光驱采用恒定线速度CLV(Constant Line Velocity)的读盘方式,即光驱阅读光盘内圈时,光盘旋转得很快,而光驱阅读光盘外圈时,光盘旋转速度放慢。高速光驱(30倍速或以上)的工作方式有两种:CAV(Constant Angular Velocity,恒定角速度)和PCAV(Partial-CAV,局部恒定角速度)。采用恒定角速度CAV的读盘方式时不论光驱在阅读光盘的内圈还是外圈,光盘都以恒定的速度旋转,光盘内圈的周长无论何时都会小于外圈,而光盘上存取数据区域的密度是恒定的,愈长的周长意味着愈多的数据,也就是说采用CAV技术的光驱在读取盘片外圈和内圈时的传输率不一样,这样的光驱只有在读光盘外圈时才基本达到其标称速
Optical drive generally use double speed that its transfer rate. In the development of standards, the transfer rate of 150K bytes / sec as the standard, and later the optical drive faster and faster, there was a double speed, quadruple speed until now 32 times, 40 times or even 50 times the speed (the transfer rate of 150 × 50 = 7500K bytes / second). In the past, the optical disc drive used a Constant Line Velocity (CLV) read mode. That is, when the optical disc drive reads the inner circle of the optical disc, the optical disc rotates very fast. When the optical disc drive reads the outer circle of the optical disc, the rotation speed of the optical disc is slowed down. There are two ways to work with a high-speed optical drive (30x or faster): Constant Angular Velocity (CAV) and Partial-CAV (PCAV). When using constant angular velocity CAV read mode, the optical disc rotates at a constant speed regardless of whether the optical disc drive is reading the inner or outer ring of the optical disc. The circumference of the inner circumference of the optical disc is smaller than the outer radius at any time, and the data area The density is constant, the longer the circumference means more data, that is to say using the CD-ROM drive CAV technology in reading the disc outer ring and the inner ring when the transfer rate is not the same, this drive only in the CD-ROM Only when the ring reached its nominal speed