pvadbx;146005 Wrote: > So the speed of the transport motor is constantly changing to keep the > small buffer at an appropriate level?
This is how CD and DVD player's work. The data is recorded at "constant linear velocity"- i.e. each bit on the disc is physically the same size, so at the start of the disc when the laser is reading near the spindle, the disc spins very fast. As the laser moves away from the spindle, the disc slows down. The speed is constantly decreasing as the disc is played/recorded. This is why those high end belt drive CD players with 5 kg platters that rotate with the disc seem very strange. The motor that drives that assembly is going to have to do a lot of work to get the right speed, mainly acting as a controlled brake once the disc has been spun up to starting speed. All that mechanical stuff can be done away with by using a cheap CDROM drive dumping the data into a buffer. The mechanism that moves the laser and focuses it is very slow compared to the head positioners in a HDD. That is probably why DVDs don't use a HDD storage/EC type scheme. Also, there is limited capacity in the discs to store all that extra ED/EC info. TD -- tyler_durden ------------------------------------------------------------------------ tyler_durden's Profile: http://forums.slimdevices.com/member.php?userid=2701 View this thread: http://forums.slimdevices.com/showthread.php?t=28621 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
