Problems with Recording (Including Buffer Underruns)

Problems with Recording

1. What is a buffer underrun and how is it caused?

2. What are common causes of Buffer Underruns and what can I do to prevent them?

3. I cannot directly copy from my CD-ROM drive to the recorder, why not?

4. My CD-RW is not allowing me to burn at the speed the drive is rated at (eg a DD321040 is only allowing a top burn speed of 16x to my CD-R media, not 32x). How can I resolve this?

5. Running Nero Burning Rom in Windows 2000 and XP, CDs can only be burnt when logged in as an Administrator. How can this be changed so CDs can be burnt when logged in with a User account?

 

1.What is a buffer underrun and how is it caused?

An uninterrupted data flow to the CD Recorder is required when using recording software such as Nero Burning Rom. A buffer underrun occurs when the PC cannot consistently send the required amount of data to the CD recorder. The data is stored in a buffer before it is written to the drive. If the data is taken from the buffer and written to the disc at a faster rate than new data is received by the buffer from the PC, then the buffer can empty very quickly and an error occurs on the CD due to the buffer underrun.

The required amount of data is 2400 KB/sec when writing at 16X, 1200 KB/sec when writing at 8X, 600 KB/sec when writing at 4X. If a buffer underrun occurs during writing, your CD-R disc will be unusable. If a buffer underrun occurs while writing to a CD-RW disc, you will need to erase the disc before it can be used again.

For information about common causes of buffer underruns and some solutions please refer to question 2, below.

 

2. What are common causes of Buffer Underruns and what can I do to prevent them?


There are a number of common causes of buffer underruns that are related to the hardware of the computer system, the operating system that is used or other programs that may be running on the PC at the same time as the CD is being recorded.

a) Hard Disk Drives

  • Fragmented hard disk drives. We recommend using the operating system‘s de-fragmentation utility at least once per week to de-fragment the files on the PC‘s hard disk drives.
  • Insufficient space in the temporary directory used by the recording program. Delete any unneeded files and use scandisk to check for disk problems and free additional disk space.
  • Hard disk compression may cause buffer underruns. We do not recommend writing from a compressed hard disk or disk partition.
  • Setting the hard drive's read-ahead optimisation to "none" may cure buffer underruns in some cases. To do this, go to the Start menu, then Settings, Control Panel, System, Performance, and Advanced Settings. Click on File System and then Hard Disk and set "Read-ahead optimisation" to "None."
  • If your source hard disk is more than five years old, make sure it is capable of smart thermal re-calibration.
  • The temporary directory that is selected for file buffering should always have space free that is at least twice the size of the largest file that you are recording.
  • At least 10 MB of free space is required for every minute of audio data that is to be written to the CD.

b) Other Hardware Issues

  • Spinning down of CD-ROM drives that are the source for data or audio tracks may cause underruns. Turn off power management or copy files from the CD into a temporary directory or separate partition of the hard disk drive to prevent this.

  • Slow source devices such as some CD-ROM drives or some types of removable disk drives that cannot provide high enough data transfer rates to the CD recorder will cause underruns. Copy the files from the source to the hard disk drive or burn at a slower speed.

  • This is particularly important if you are copying an audio CD.

  • Source devices that transfer data in bursts where the data flow is irregular and cannot be guaranteed often cause underruns.

  • Copy files onto hard disk drive before recording.

  • Depending upon the configuration of your PC, it may be necessary to write to audio CDs at slower speeds than you can achieve for data. This is because writing CD-DA audio discs requires the streaming of more bits per second to the recorder. Also, CD-ROM drives that are used as the source for audio CDs usually extract audio data at a much slower rate than their maximum read rate for data CDs.

  • An audio extraction rate of 8X is typical, but check your CD-ROM drives specifications.

  • If you are using Windows NT 4.0, install Service Pack 3 or later and update the ATAPI device drivers. The default release ATAPI 1.2 driver may cause problems by lowering the data transfer rates to/from the hard disk drive, CD-ROM and recorder.

 

c) Computer Networks

Recording data that is stored on a computer network can cause buffer underruns. The network may be too slow to maintain adequate throughput speed to the CD recorder. Copy all of the data that is to be stored on the CD into a separate partition (preferably) or an empty directory on the local hard disk drive before attempting to write to the CD. Using a separate partition minimises file fragmentation. Alternatively, create a disc image on the hard disk drive that contains all of the data that is to be written to the CD.

 

d) Problems with Data Files

  • Recording many small files can cause errors because of the extra time that the source takes to access each individual file. One way around this is to use the authoring software such as Nero Burning Rom to create a disc image, which is a file on the hard disk drive that holds all of the contents of the CD. The image can then be recorded to CD as one continuous file.
  • If using Nero software, always use the "cache small files" option.
  • Damaged source files cause read errors on the source drive and data loss.
  • Trying to record files or directories that have zero file size or that are already in use by the operating system or other applications causes underruns. Do not try to copy these types of files or directories.


e) Other

  • Copying from a source CD that is scratched, dirty or damaged will often result in buffer underruns.
  • Applications and screen savers that are running at the same time as the disc is recording may interrupt the flow of data to the CD recorder by accessing the hard disk drive or loading the CPU. Close all other applications and turn off screen savers to prevent this.
  • Anti-virus programmes can also interfere with CD recording and should be closed.
  • PC power management makes the PC slower and thus it may result in buffer underrun. Disable the power management or delay the power saving time. Microsoft recommend that power management be turned off using the Control Panel‘s Power configuration setting when recording CDs with Windows.
  • Check the minimum system requirements of the CD authoring software that you are using and ensure that your PC complies with these requirements.
  • Keep your CD recorder cool. Make sure that there is adequate ventilation in and around the case of the PC and around the drive. The source CD-ROM drive and CD-recorder may not operate correctly if they overheat.
  • Record at a lower speed - it takes longer to empty the buffer when recording at 4X speed making recording more stable.

 

3. I cannot directly copy from my CD-ROM drive to the recorder, why not?

  • Some older types of CD-ROM drives will not allow direct copying to the CD recorder or are not capable of digital audio extraction and so cannot be used as a source to copy audio CDs.

  • Some CD formats have copy protection or other features that do not allow a CD-to-CD copy.

  • Extracting audio data from a music or game CD often causes problems, particularly when recording at 8X or above. This is because most CD-ROM drives can only extract audio data at speeds of 8X or less. Check your CD-ROM drives specifications.

 

 

4. My CD-RW is not allowing me to burn at the speed the drive is rated at (eg a DD321040 is only allowing a top burn speed of 16x to my CD-R media, not 32x). How can I resolve this?

Please check the following:

  • Make sure that you are using CD-R media, and not CD-RW media. CD-RW media is generally rated at slower speeds than CD-R media.

  • Make sure that the blank CD-R media you are using is rated at the speed you want to burn at. If your burner is capable of writing to CD-R media at 32x, make sure your CD-R media you have has a rating of 32x or higher.

  • Your CD-RW drive may require a firmware update. Firmware updates for all Diamond Data models are available in the File Downloads section of this website. (CAUTION: be sure to follow the firmware upgrade instructions carefully when updating your CD-RW drives firmware).

 

 

5. Running Nero Burning Rom in Windows 2000 and XP, CDs can only be burnt when logged in as an Administrator. How can this be changed so CDs can be burnt when logged in with a User account?

Please download and install the Nero BurnRights program from the Nero website. This software patch will allow you to give unlimited burning rights in Windows 2000 and XP. The website is:

http://www.nero.com/en/content/c1023694368810.html