[MacDV] "The device drained its buffer without burn underrun protection."

Michael Winter winter at mac.com
Mon Dec 12 07:23:07 PST 2005


On Dec 11, 2005, at 8:03 AM, Norm Loomer wrote:

> I'm trying to use Disk Utility to burn copies of a DVD disk image.  
> Three times in a row--with two different blank DVDs--the disk has  
> ejected and I have received the message, "The device drained its  
> buffer without burn underrun protection." What does that mean, and  
> what can I do about it?

Short answer, the computer couldn't keep up with the DVD drive, so  
slow the drive down (reduce burn speed) or speed the computer up  
(quit other programs).

In order to burn data to a disk, the computer sends the information a  
little at a time to the CD/DVD burner. The burner has a little bit of  
memory to hold the data (its buffer). The drive pulls data out of the  
buffer to burn to disk. So, from a data flow perspective, data goes  
from computer -> drive's buffer -> DVD.

What can happen is that the computer, for some reason, can't put data  
into the buffer faster than the drive can take it out and burn it.  
When that happens, you get a buffer underrun, there's no data  
available for the drive to write to the disk when it needs it. Any  
interruption like that results in a failed burn. To prevent that, you  
need to prevent the drive from burning to disk faster than the  
computer can send it the data. The best way to do that is to slow  
down the burn speed, If that doesn't work, turn off all other  
programs that may be slowing the computer down.

Underrun protection is a feature of some newer (actually been around  
for years) drives that, combined with the right software, allows the  
drive to recover and continue burning the disk even after an underrun  
occurs.

-Mike




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