4.3. DVD±RW Writing Methods
Disc at Once (DAO) – A DVD writing process in which the entire DVD is recorded in one session, and data cannot be added after the recording is finished. This differs somewhat from the CD-R DAO method because the lead-in area, data area, and lead-out area are all written sequentially.
Session at Once (SAO) – A writing process which is similar to DAO, where information is written in a session, but allowing for record further recording at a later time. This mode provides for greater control of the recording process than Packet Writing (PW) or TAO, and more disc space can be utilized because there is no need for gaps between tracks.
Incremental Recording (IR) – A writing process that is similar to the Session at Once (SAO) CDR writing method; files may be added directly to the DVD-R disc one recording at a time, instead of record- ing the files to a hard drive before writing the disc. The minimum recorded size, though, must be at least 32KB (even if the file to be recorded is smaller than that), and capacities and write speeds are decreased due to the overhead of combined lead-in/out areas and data. Also, the disc must be finalized before it may be played back by a drive other than the drive recording the disc.
Multi-Border Recording (MBR) – A writing process that is very similar to IR, MBR allows you to make an IR disc and then play the disc back on a device that recognizes this type of recording method. MBR creates a very short boundary zone around a recording ses- sion so a compatible player or DVD-ROM drive does not attempt to play beyond the border of the recorded area, instead allowing the unfinished disc to be read by a player that supports this recording method.
Restricted Overwriting (RO) – With this method, if a disc has already been written to, new data segments can be randomly inserted any- where within the recorded boundary. New data, however, can only be added to an area of the disc that has already been recorded over and from the point where the last session was stopped.
Packet Writing (PW) – A drag-and-drop writing process that is very useful for data backup. Buffer underrun* is impossible in this mode, because the data is written in “packets” of a few KBs. Packet Writing is a CPU-intensive process because it constantly checks the avail- able space on the disc.
*Buffer Underrun – The recording of a disc is a system-intensive ap- plication, and the rewritable drive needs a constant stream of data. A buffer underrun occurs when the stream of data to the rewritable drive is not fast enough to keep the rewritable drive’s buffer full, causing an error in the recording process. If this problem occurs often, turn down the recording speed.
