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DAW Optimization in Windows 9x
 

If you're having problems with clicks and pops in Windows 9x. Here are some optimization tricks that you can try.

The Windows 9x operating system may have difficulty with real time applications for many reasons, but the dynamic disk caching and the multitasking time slicing are the two that most concern Your Audio Application's environment.

These suggested optimizations are recommended to avoid clicks/pops and audio glitching within the Windows 9x platform.

Below are steps that can be taken to optimize Windows 9x for audio and video real-time applications, in the order of importance. We recommend starting at the top of the list and making the minimum amount of changes needed to hopefully solve your particular problem. Try at least the first three suggestions.

Windows 9x will normally ask you to restart after each one of these adjustments, so it is recommended that you close all applications before making these changes. To save time, you may select "No" to the Windows restart prompts until the last change has been made.

Optimization Suggestions

Virtual Memory Size

The virtual memory swap file seems to be one of the most troublesome areas of the Windows 9x platform for real-time applications such as Your Audio Application. By default, Windows 9x allows this swap file to be resized dynamically as the operating system runs. This resizing leads to system delays which may cause clicks/pops or audio glitching to happen during audio playback.

Setting the virtual memory size of Windows 9x to prevent resizing of the swap file can have a big impact on improving Your Audio Application’s performance.

To Set Virtual Memory Size:

  1. Click Start on the Windows 9x Taskbar. Click Settings and choose Control Panel.
  2. Double-click the System icon.
  3. Click the Performance tab.
  4. Click the Virtual Memory button.
  5. Click the option Let me specify my own virtual memory settings.
  6. Set both the Minimum and Maximum values to the same setting to prevent repeated resizing of the swap file (i.e. a setting of 256 in both cases would create a swap file of 256 MB). There is no hard and fast rule regarding the size of your swapfile (i.e. "twice your RAM" or whatever is not always the case, but is a good ‘standard’ rule of thumb) - the user really needs to determine how much they need (and in the case of smaller HDs the amount they can spare). The most efficient use would be to allocate a fixed swapfile only slightly larger than you ever need to access (as determined by actual testing, not by some formula), although when in doubt you should err on the side of larger rather than smaller.
  7. Click OK to accept your changes.

CD-ROM Auto Insert Notification

By default, Windows 9x is set to continuously check the CD-ROM for the insertion of a CD so that it may automatically run the CD setup program. This can result in audio glitches during playback and recordings because it forces Windows 9x to continually time-slice all other running applications. This will also interfere with the ability of a CD-R burner to write a CD by causing the SCSI controller to error out if it checks the CD-R at the same time a CD is being burned.

To Disable CD Auto Insert Notification:

  1. Click Start on the Windows 9x Taskbar. Click Settings and choose Control Panel.
  2. Double-click the System icon.
  3. Click the Device Manager tab.
  4. Click the plus sign next to the CD-ROM listing to expand the list of CD-ROM devices.
  5. Select your CD-ROM and click the Properties button.
  6. Click the Settings tab.
  7. Uncheck the Auto Insert Notification checkbox.
  8. Click OK to save your changes.
  9. Follow this procedure for each CD-ROM installed on your system.

Write Caching

By default, Windows 9x is set to enable disk write file caching. This function allows Windows 9x to write disk files in the background at some later time, rather than at the moment you initiate a disk write procedure. When recording soundfiles in Your Audio Application, the data is presented to the disk in one continual streaming operation, leaving no time for background writing operations. When write file caching is active, Windows 9x tries to put the data in RAM first, waiting for an opportune time to write it to disk in the background. This opportune time never comes, and Windows 9x runs out of RAM space, interrupts Your Audio Application trying to quickly empty its cache to disk, and potentially loses incoming data, causing audio glitches in the recording.

To Turn Off File Write-Caching:

  1. Click Start on the Windows 9x Taskbar. Click Settings and choose Control Panel.
  2. Double-click the System icon.
  3. Click the Performance tab.
  4. Click the File System button.
  5. Click the Troubleshooting tab.
  6. Check the Disable Write-Behind Caching For All Drives checkbox.
  7. Click OK to save your changes.

Read Caching (Overall system performance can be slowed from this change, so use only if necessary)

By default, Windows 9x caches all disk reads to RAM. Normally read caching can be an advantage for Your Audio Application. Problems can occur, however, when Windows 9x dynamically resizes the amount of space allocated for the read-cache buffers. This can cause audio glitching during playback.

To Limit the Maximum File Read-Cache Size:

This procedure requires a good working knowledge of the Windows 9x environment. If you’re not comfortable with the following steps, solicit the help of someone well-versed in the Windows 9x platform.

  1. Using Windows Explorer, navigate to your Windows folder, and double-click the System.ini file to open it into the Notepad application.
  2. Scroll through the file looking for a section labeled [vcache].
  3. Create a blank line under the [vcache] heading and type MaxFileCache = 4096. If this entry already exists, just change the size value. Make sure the upper case and lowercase letters are maintained, otherwise this line will not work.
    (This limits the maximum file cache size to 4096 Kilobytes (4 Megabytes). You can experiment with different sizes, but the size specified should be in increments of 1024 and it is recommended that the size not be made less than 2048.)
  4. Save the file and close Notepad. Restart Windows 9x for this change to take effect.

Double Buffer

In some cases, depending on your disk configuration, Windows 9x may create a double buffering scheme for handling disk transfers. This can cause serious audio glitching during record and playback.

To Disable Double Buffering:

This procedure requires a good working knowledge of the Windows 9x environment. If you’re not comfortable with the following steps, solicit the help of someone well-versed in the Windows 9x platform.

  1. Using Windows Explorer, navigate to the root directory of your boot drive.
  2. Right-click on the MSDOS.SYS file and select Properties from the popup menu.
  3. Uncheck the Read Only checkbox.
  4. Click OK.
  5. Double-click on the MSDOS.SYS file and choose Notepad to open the file.
  6. Scroll through the file looking for a section labeled [Options].
  7. Create a blank line under the [Options] heading and type DoubleBuffer=0. If this entry already exists, make sure it is =0, not 1. Make sure the upper case and lowercase letters are maintained, otherwise this line will not work.
  8. Save the file and close Notepad.
  9. Right-click on the MSDOS.SYS file and select Properties from the popup menu.
  10. Check the Read Only checkbox.
  11. Click OK.
  12. Restart Windows 9x for changes to take effect.

Additional Suggestions

If the above suggestions do not work, here are some additional options you may try.

Video Cards

Go for an AGP adaptor if possible. AGP not only frees the PCI bus for PCI cards, it will also improve the performance for ISA cards. However, (if using a VGA card) some (VGA) video cards can interfere with the PCI bus and/or DMA operations. Many of the newer hardware accelerated video cards will contain their own specialized applet or settings tab in the Windows 9x Display Properties control panel. If a checkbox exists referencing PCI bus retries or DMA bus mastering, or something similar, try disabling this option.

Graphics Hardware Acceleration

Some video cards hardware acceleration interactions can be controlled directly from the Control Panel in Windows 9x.

To Reduce Graphics Hardware Acceleration:

  1. Click Start on the Windows 9x Taskbar. Click Settings and choose Control Panel.
  2. Double-click the System icon.
  3. Click the Performance tab.
  4. Click the Graphics button.
  5. Adjust the Hardware Acceleration slider control one notch to the left to lower the setting.
  6. Click OK to save your changes.

After restarting Windows 9x, if the problem persists, try adjusting this setting one notch lower, until the desired results are achieved. If the lowest setting does not work, it is recommended that you reset the control to the highest setting.

Media Control

By default, the Media Control Interface (MCI) will allocate a certain amount of memory to buffer from 2 to 9 seconds worth of audio for the default audio wave device. This can introduce a double buffering condition and may cause clicks/pops and/or audio glitches when using Your Audio Application.

To Disable the Wave Audio Device:

  1. Click Start on the Windows 9x Taskbar. Click Settings and choose Control Panel.
  2. Double-click the MultiMedia icon.
  3. Click the Advanced tab.
  4. Click the plus sign next to the Media Control Devices listing to expand the list.
  5. Select the Wave Audio Device (Media Control) and click the Properties button.
  6. Select the Do not use this Media Control device option button. (OR click the Settings button, and adjust the slider control all the way to the left to the minimum setting.)
  7. Click OK to save changes.

Computer Role

Windows 9x allows you to select different role types for your computer system, and it appears that memory and disk handling may be treated differently depending on the type selected. Sometimes selecting a different role type may be the solution.

To Change the Computer Role Type:

  1. Click Start on the Windows 9x Taskbar. Click Settings and choose Control Panel.
  2. Double-click the System icon.
  3. Click the Performance tab.
  4. Click the File System button.
  5. Change the typical role of this machine to Network Server.
  6. Click OK to save your changes.

Background Processing

  • Ensure that all power management functions are disabled on the computer.
  • Ensure that no memory resident virus software is installed. Software of this type intercepts all disk access and can cause audio glitches due to these delays.
  • Ensure that no disk compression software is enabled on any drives regardless of whether these drives are used for audio data or not.
  • Ensure that no RAM doubling software is installed.
  • No task monitor.
  • No screensaver.
  • No system sounds.
  • No icons on the Task Bar - not even the clock.

Miscellaneous

  • TweakUI in Control panel with all settings adjusted for minimal system drain and memory use.
  • Nothing in the Startup folder.
  • Use seperate drives for system and audio data.
  • Format your Audio Drive using the /Z:64 option as this increases the cluster size (less HD reads) and results in better performance. Usage (where d: is the audio drive) format d: /Z:64
  • Ensure that DMA is enabled on ALL IDE drives that support it, including CD Rom drives.
  • Defragment ALL drives regularly and especially after a heavy editing session.
  • No fonts except those loaded by windows and program specific fonts.
  • Under system information, check that IRQ's are not being shared, especially video/soundcards.
  • Again under system information, in system configuration utility - only TweakUI and Power profile should be loaded.
  • No Enabled Desktop.
  • Make sure you don't have any compressed drives.
  • An item added to the [ENH32] section in System.ini ConservativeSwapfileUsage=1

Links to Audio Related FAQ's etc..

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