How Buffer Underrun technology hinders CD Recording Performance

Dennis Faas's picture

If you own a CD Burner, there's a good chance that you've come across a "Buffer Underrun" error message. A buffer underrun happens when information cannot be recorded to the CD because of resource starvation. All CD recorders without buffer underrun protection require a constant flow of data to be read from the hard drive to the CD recorder without interruption. If the flow of data is stopped, a buffer underrun will follo w.

For example, if your hard drive can only read information at a rate of X and the CD Recording needs information at a rate of X+1, this is referred to resource starvation and a buffer underrun will ensue.

To counter this dilemma, anti buffer underrun technologies, such as Safe Burn, Just Link, Burn-Proof, and Power Burn were introduced by various companies. For the most part, all buffer underrun protection schemes achieve one goal: they stop resource starvation.

However, some anti buffer underrun technology -- such as Power Burn technology, found in Sony CD recorders -- can severely hinder CD recording performance by adjusting the CD recording speed to well below the safe level of continuous information flow. Other anti buffer underrun technologies use a linking method to prevent buffer underruns by continually pausing and resuming the recording process. Every time the recorder pauses to reintroduce the information it missed, it must produce a data link from previous recorded data to the newly recorded data. This dramatically increases the time that it takes to record a CD. This is also very highly undesirable when creating an Audio CD because the links can distort the audio. Without getting too technical, the point is that the CD recorder isn't recording at its optimal speed.

So how do you know if your CD recorder is using anti buffer underrun technology, and whether or not it's running at an optimal rate?

The answer to each question is simple and clear cut. First of all, anti buffer underrun technology was recently introduced within the last year - at around 12x and 16x recording speeds. So, if your CD recorder is less than 12x speed, there is a good chance that you do not have anti buffer underrun technology.

Secondly, most CD recording software allow the user to disable underrun technology. If you're trying to record a perfect audio CD and don't want distortion caused from "links", disable it before burning the CD. But be forewarned, you might end up burning a bad disc because of resource starvation. Uh oh!

Fear not -- there is a better way to find out if your CD recorder is burning at its optimal speed:

1. For the next CD you create, note how long your CD recorder takes to burn at its maximum recording level. Approximate recording times for a full 700 meg CD, based on CD recorder drive speeds are: 2x speed @ 30 minutes, 4x speed @ 15 minutes, 8x speed @ 9 minutes, 16x speed @ 6 minutes, and so on.

The next time you burn a CD, pay close attention to your recording buffer as the CD records. Most CD recording software will display the buffer during the recording process. While the CD is recording, observe how much the buffer fluctuates. If it dips up and down dramatically, your CD recorder is most likely using buffer underrun protection.

2. Without turning off the buffer underrun protection, adjust the CD recording speed down a level. For example, if your CD recorder is 16x and the software recording speed is set at "maximum" or 16x, try adjusting it the next level down (usually either 12x, 10x, or 8x). Take note how long it takes to burn your next CD and pay attention to how the buffer fluctuates. If it the buffer doesn't dip up and down (or side to side) as it did previously, you've found the optimal recording speed of your CD recorder, matched with your particular system setup.

If the buffer has stabilized after adjusting the recording speed, it should also take less time to record a CD. I've come across a computer with a 16x CD recorder with buffer underrun protection that recorded a CD at "maximum" speed (which should be 16x) and it took 30 minutes to record, when in fact, it should have only taken 6 minutes.

Good luck!

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