Buffer Underrun - CD and DVD Recording Issues

CD and DVD Recording Issues

Buffer underruns can cause serious problems during CD/DVD burning, because once the writing is started, it cannot stop and resume flawlessly; thus the pause needed by the underrun can cause the data on the disc to become invalid. Since the buffer is generally being filled from a relatively slow source, such as a hard disk or another CD/DVD, a heavy CPU or memory load from other concurrent tasks can easily exhaust the capacity of a small buffer. Therefore, a technique called buffer underrun protection was implemented by various individual CD/DVD writer vendors, under various trademarks, such as Plextor BurnProof, Nero UltraBuffer, Yamaha SafeBurn, JustLink, and Seamless Link. With this technique, the laser is indeed able to stop writing for any amount of time and resume when the buffer is full again. The gap between successive writes is extremely small.

Another way to protect against the problem, when using rewritable media (CD-RW, DVD-RW, DVD-RAM), is to use the UDF file system, which organizes data in smaller "packets", referenced by a single, updated address table, which can therefore be written in shorter bursts.