Verifying audio read quality

Audio data from CDs is read digitally for the purpose of saving audio tracks to hard disk and copying CDs.

Yes, you did read that correctly - digitally. All CD/DVD-ROM drives can play audio CDs in analogue format (i.e. through head sets or sound card) but not all can read audio data digitally and even then only a few of these drives produce good quality audio reading. So: the digital extraction of audio data is essentially different from simply playing an audio CD.

In practice the quality of the digitally read audio data is never going to be satisfactory. For example sometimes there are "jumps" in the audio data which are noticeable as unpleasant clicking noises when playing a saved audio file or listening to a copy CD. The amount of such defects in the audio data is heavily dependent on the type and make of the CD/DVD-ROM drive.

Before extracting audio data or copying CDs each owner of a CD ROM should be aware of how good the audio read quality of his own CD/DVD-ROM drive is. Armed with this knowledge unusable CD copies can be avoided by selecting better copy options. To diagnose your CD-ROM proceed as follows:

  1. First of all please check to see whether your CD/DVD-ROM drive is already supported by Nero. Look up whether the command Autodetect CD ROM is available on the Extras menu. If so run through the CD/DVD-ROM autodetect first of all (see Section 'Autodetection of CD/DVD-ROM drives'). If the command is highlighted in gray and therefore cannot be activated the installed CD/DVD-ROM drive has been detected.
  2. Now insert the Nero CD into the CD/DVD-ROM drive. If this starts the installation of Nero cancel this as Nero has already been installed.
  3. Choose the command Save Track from the Recorder menu and select your CD/DVD-ROM drive as the source drive. Select the second track (and/or the first audio track) and save as a wave file on your hard disk.
  4. Now from the File menu find the New command for a new audio compilation and then drag the wave file extracted in Stage 3 into the audio compilation.
  5. Double click on the track of the audio compilation corresponding to the wave file.
  6. Click on the tab Indices, Limits, Split. You will see a colored rectangle. Zoom several times into the graphical view of the audio file by clicking on the appropriate button until a zigzag line (a so-called "saw tooth") can be seen. The upper row corresponds to the left stereo channel and should have an even "zigzag line" (or more specifically a "saw tooth") and the lower row (right stereo channel) a horizontal line.
  7. When looking closely at audio data it usually corresponds to one of the following three quality stages:

    If there is a repetitive, regular zigzag line in the upper half over the entire area and a horizontal null line in the lower half, your CD/DVD-ROM drive has very good audio read qualities. If your drive can also read audio data quickly there is nothing to prevent you using your drive for fast copies of all kinds.

    If the zigzag line appears exclusively in the upper row but sometimes has irregularities compared to previous or later runs, as if parts had been cut out and added again at some other point, your CD/DVD-ROM drive suffers from the "jitter effect" and is therefore only suitable to a limited extent for fast copies. If used for fast copies or to save audio tracks the burnt CD and/or the saved file may possibly contain unpleasantly audible clicks in the audio data. The CD/DVD-ROM drive can be used without any problems for fast copies of data CDs but only conditionally (i.e. allowing for loss of quality) for copying CDs with audio tracks.

    If the zigzag line sometimes appears in the upper and sometimes in the lower row or if both displayed channels contain only "nonsense" (for example both channels have horizontal lines or quite different forms than the expected zigzag line on the left/upper channel) your CD/DVD-ROM drive does not have such good audio read quality. In this case we would seriously discourage you from using your CD/DVD-ROM drive for fast copies of CDs containing audio tracks or for saving audio tracks. The CD/DVD-ROM drive may, however, be used without any problem for fast copies of data CDs.

    Nero CD Speed

    You can also verify the audio read quality (DAE - Digital Audio Extraction) of the CD-/DVD drive using the benchmark program Nero CD Speed, a component of the Nero CD. You will find more details of this program in the chapter on Nero CD Speed.

    See also:

    Copying using an image file

    Copying using a fast copy (on the fly)

    Setting speed on CD/DVD-ROM drives


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