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davidsay

Buffer Only 1 To 2 %

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Hi,

When I do a CD to CD copy, the buffer is only at 1 to 2%, thus program is writing at 1X to 2X only (Even though I tell it to write at 8X).

I'm copying from a Samsung CD-ROM SC-140 to a Toshiba DVD-ROM SDR1202. The resulting copy is good but it's SO SLOW. What am I doing wrong?

THANKS!

Al

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Hello Al,

 

Drive to drive copying is called "on the fly" copying, and isn't recommended because of the problem you're seeing.

 

You're suffering "buffer underrun", and if you had an old burner this condition would kill your copy every time. The ability to recover from these is a feature of newer drives.

 

What's happening is that the system [reader drive and software processing] can't get data off the CD and into your writer fast enough, and your writer's data buffer is running dry. When this happens the writer stops until the buffer fills up some, and then restarts and immediately sucks the buffer dry again, and round we go again. The effective speed when this happens can be way less than 1x.

 

You haven't said if it's a data CD or an audio one you're copying, but typically audio takes twice the time to process that data takes. Also, some readers can't "extract" audio as fast as others. Further, an error reading a less than perfect disc may cause an attempt to re-read and this will slow things down even more.

 

In any case, there are two things you can do to stop this happening:

1) Slow the burn to 4x. You might be able to sustain that speed, whereas you can't sustain an 8x burn, and the result will be faster than stopping and starting with an underrun all the time.

2) Use your fastest extracting drive to make a disc image on the hard drive (it can take as much time as it needs) and then burn from that image, as fast as your burner can go. This will work, whereas method 1 might not.

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Hello Al,

 

Drive to drive copying is called "on the fly" copying, and isn't recommended because of the problem you're seeing.

 

You're suffering "buffer underrun", and if you had an old burner this condition would kill your copy every time. The ability to recover from these is a feature of newer drives.

 

What's happening is that the system [reader drive and software processing] can't get data off the CD and into your writer fast enough, and your writer's data buffer is running dry. When this happens the writer stops until the buffer fills up some, and then restarts and immediately sucks the buffer dry again, and round we go again. The effective speed when this happens can be way less than 1x.

 

You haven't said if it's a data CD or an audio one you're copying, but typically audio takes twice the time to process that data takes. Also, some readers can't "extract" audio as fast as others. Further, an error reading a less than perfect disc may cause an attempt to re-read and this will slow things down even more.

 

In any case, there are two things you can do to stop this happening:

1) Slow the burn to 4x. You might be able to sustain that speed, whereas you can't sustain an 8x burn, and the result will be faster than stopping and starting with an underrun all the time.

2) Use your fastest extracting drive to make a disc image on the hard drive (it can take as much time as it needs) and then burn from that image, as fast as your burner can go. This will work, whereas method 1 might not.

 

Or, since I didn't have access to Brendon's wealth of expertise at the time, I used to make my Music CDs TAO (Track at Once) instead of DAO (Disc at Once) - it's a toggle switch along the bottem of the MusicCD layout. The resultant CD will have an extra 2 seconds between tracks (for the laser to turn off and on) and won't be recognized by CDDB if you go online to have the data filled in (I don't), but it will give the burner time to catch up, especially on the outer tracks. (And it's always a good idea to go slower than the fastest speed a burner can burn, since often thesystem can't keep up - 4x, as Brendon says.)

 

Lynn

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