How fast can data be read from or written to a Blu-ray disc?
1x speed is defined as 36 Mbps, according to the Blu-ray Disc specs. BD-ROM movies will require a 54Mbps data transfer rate, so its safe to expect the minimum speed to be 2x (72Mbps). Due to the larger numerical aperture (NA) adopted by Blu-ray Disc, Blu-ray has the potential for much higher speeds. The larger NA value will require less recording power and lower disc rotation speed than DVD and HD-DVD to achieve the same data transfer rate. In the past, the media itself limited the recording speed. However, the only limiting factor for Blu-ray is the capabilty of the hardware involved. With a maximum disc rotation speed of 10,000 RPM at the outer diameter, a speed of 12x (about 400Mbps) could be possible. Thus, the Blu-ray Disc Association (BDA) currently has plans to raise the speed to 8x (288Mbps) or possibly more in the future.
