CD Burning Problem: Buffer Underrun Guide
July 16, 2002
by Chris Pun
I ran into an article the other day that felt interesting and would like to share with all our TekGuide.net viewers.
Buffer Underrun Errors - How to waste CDR:s
When burning audio-cd's it is absolutely critical that the data-stream from the harddrive to the CD-writer is as continious
as possible. The CD-writer has an internal memory-buffer to compensate for small gaps, but if your harddrive or your CPU is
interrupted for to long, the CD-writer will run out of data. Because the CD-writer cannot wait, this will cause gaps and noise
in the music, or in the worst case, it will ruin the entire disc. Buffer Underrun errors are a common problem when burning CDs.
The source of the problem
So, why is the CPU interrupted? Windows is a multi-tasking operation system, meaning it can run many programs
simultaneously. The CPU, however, can only do one thing at a time. To solve this problem, Windows divides the CPU-time into
small slices and gives each running program a short period of time to execute, before the CPU is handed over to the next
program. The more programs you run, the smaller each time-slice gets. If the slices are to small, there may not be enough time
for the burning-software to fill the buffer on the CD-writer.
What about the harddrive? Just like the CPU, the harddrive cannot read everything at the same time. If, for example, some
antivirus software or a screensaver starts in the middle of your cd-burning-session, the harddrive may get occupied with other
things and stop reading CD-data.
What can you do to prevent "buffer underrun errors"? There are a few things you should always do before burning audio-CDs:
1. Reboot the computer before you begin to make sure the operating system is completely stable (You never know after running
a few games).
2. Terminate all programs but the cd-burning-software.
3. Don't use your CD-writers maximum burnings speed if you have get any gaps or jumps in the music. If your writer can burn
at 4x use 2x, if can handle 8x use 4x and so on. This way, the CPU will only have to send half as much data to keep the buffer
full. Making the whole process less sensitive to errors.
4. Try increasing the priority of the CD-burning software. You may have to try a few different settings before you find the
optimal priorities for your system.
5. Always cache to harddrive before burning.
Here's where I received the