[plug] Buffer full

[Dennis Plester]

Nigel wrote:

"Hi list,

Lately I have been using gdrdao (a front end for cdrdao) to burn VCDs.
Today when i went to write the CD I got a buffer underrun error. On looking
at gdrdao, I now see see that the buffer size is set to 0. I tried rebooting
the machine (i wanted to do a new kernel compile anyways), and running it as
soon as I started X to see if any other programs might be causing the
problem. No luck.
Anyone have any ideas what might cause this. The rest of the system seems
fine. The only thing i've been playing with recently is putting vmware on.
Nigel"
I have no experience with gdrdao or cdrdao, but I've done a lot of burning
in my time in both windows and Linux. Was the buffer size set to a different
value rather than 0 before, or have you only just noticed it. Usually when
you get buffer underruns, the problem is associated with the buffer inside
the burner itself, which is fixed and totally unrelated to any settings in
the burning software, or the operating system. Most burners have 2 - 4 MB
but some of the faster burners have more.
Many burning programs also allow you to set up an additional buffer, using
some of your system RAM, which is what you are referring to. Xcdroast for
example, sets a 4MB buffer of its own by default, but I've had it set to
zero previously, and yet I still successfully burnt CDs without a problem as
my burner, like all burners has its own buffer anyway. Setting additional
buffer capacity simply gives you more time for the harddisk to catch up with
the burner before the flow of information gets broken.
There are many reasons for buffer underruns. The first thing to do is to
shutdown all unnecessary services and programs at the time of burning, and
disable screen savers and network connections if the problems continue.
Another option is to reduce the burn speed. If your computer can't keep up
at 4x, try 2x and then 1x. Try the burn using simulate or dummy burn mode if
the software supports it. If you make it through a simulation without buffer
underrun, you will be able to burn the CD with any buffer problems. That
way, you can try it without making coasters.
If you already know all of this, I'm sorry for stating the obvious, but
additional system load at the time of burning is the primary cause of buffer
underruns, not software settings, operating system config, etc. You're not
running Vmware while you are burning are you? Unless you have an absolute
heap of RAM, this would be really pushing your luck.
Hope this helps.

BTW, is gdrdao/cdrdao any good? Does it have advantages over any of the
other packages, apart from burning disk at once, which Xcdroast does now
anyway?

Dennis.