Optimizing Windows for Audio & MIDI
Contents
General information
Many seemingly innocuous features can cause problems with digital audio and MIDI programs. Such problems can result in audio pops and clicks, or even audio dropouts. Fortunately, these problems can be avoided by careful configuration of the Windows system to ensure reliable audio performance, as described below.
Use model-specific drivers for Ultra DMA hard disk
controllers
If you have an Ultra DMA 66/100 hard disk controller, make sure you are using the controller's model-specific drivers. Also, make sure that the drivers are up to date. Using generic hard disk controller drivers, or outdated drivers, can negatively effect transfer rates.
Assign a high-priority IRQ to OASYS PCI
If possible, set your BIOS to assign a high-priority IRQ to Oasys PCI. (For directions on working with the BIOS, see the documentation for the computer motherboard.)
The IRQ priority is, from highest to lowest, 0, 1, 8, 9, 10, 11, 12, 13, 14, 15, 3, 4, 5, 6, 7. Not all of these will be available for PCI cards. High priority IRQs that are commonly available for PCI card usage are 9, 10, or 11. If none of these are available, the next best alternatives are usually 3, 4, or 5. Again, make sure to check the documentation for your particular motherboard.
Set the swap size to a single value
Repeated re-sizing of the virtual memory swap file can cause problems with real-time processes. You can prevent this by setting the size of the swap file to a single, constant value. To do so:
1. For Windows 95, open Control Panel/System/System Properties/Performance/Virtual Memory. For Windows 98, open Control Panel/System/Performance, and then press the Virtual Memory button.
2. Set the Max and Min sizes to the same value.
This restrains the swap file to a single size.
It's a good rule of thumb to set the swap size to match the amount of installed RAM. For instance, if you have 128 megabytes of RAM, set the Max and Min sizes to 128 megabytes as well.
In some cases, you also may be able to diminish the amount of virtual memory swapping by changing the "typical role of this computer" (in the File System screen) to Mobile or Docking system, instead of Desktop Computer.
Set a maximum size for the disk cache
Windows' dynamic disk caching can cause problems with real-time applications. When the cache grows to be very large, the task of maintaining the cache can tax the processor to the point that it can't keep up with audio processing, which leads to audio dropouts.
You can prevent this by editing SYSTEM.INI to limit the cache size to a manageable level. To do so:
1. In the Start menu, select Run.
2. Type SYSEDIT.
The System Configuration Editor will appear.
3. Select the SYSTEM.INI window.
4. Search for a section of the file labeled [VCACHE], and make sure that the MaxFileCache is set relatively low - for slower processors, try a value of 4096.
This will limit the maximum cache size to 4096k (4 megabytes). You can try other values, if you like, but this is a good starting place.
If you cannot find the [VCACHE] section, scroll the window until you see the section labeled [386ENH], and after that section manually add the following lines (keeping capitalization exactly the same): [VCACHE] MaxFileCache=4096
Disable the Microsoft Office FastFind option
If your system includes the Microsoft Office FastFind option, disable it when using digital audio programs.
Disable write-behind cache
Write-behind caching can also cause problems with real-time processes. To disable this function:
1. Open Control Panel/System/Performance/File System/Troubleshooting.
2. Click on "Disable write-behind caching for all drives."
Disable CD-ROM "Auto Insertion Detect" or "Auto
Notification"
Windows can automatically detect the insertion of a CD-ROM into the CD-ROM drive. However, this detection can cause problems with real-time processes. To disable this function under Windows 95:
1. Open Control Panel/System/Device manager/CDROM.
2. Disable Auto Insertion Detect.
To disable this function under Windows 98:
1. Open the "System" applet in the Control panel
2. Click on the Device Manager tab.
3. Expand the CD-ROM list entry.
4. Double-click on the listed CD-ROM device.
5. Click on the "Settings" tab.
6. Uncheck the "Auto Insert Notification" checkbox.
A minimum of 2 megabytes of video RAM is
recommended
Windows may cache video data to the hard drive, which diminishes real-time performance. To minimize this caching activity, we recommend installing a minimum of 2 megabytes of RAM on your video card. (Many newer video cards come with 16 MB or more.)
Disable screen-savers
Screen-savers may cause problems with digital audio programs, so we recommend disabling them.
Additionally, single-color background screens result in faster, more efficient video performance, easing the load on the system in general.
Disable power management
The BIOS of some motherboards includes power-management features; for reliable real-time performance, these should be disabled.
Don't run networking/internet software along with
MIDI/audio
It's best not to use email, web browsers, ftp clients, and other networking and communications applications while you are running audio/MIDI programs, as these networking programs may interfere with real-time operations.
Physically disconnect networking cables
Disconnect from any dial-up communications, and if possible, physically disconnect the computer from any networking devices (ethernet, etc.).
Eliminate other unnecessary background
processes
Background processes take up CPU horsepower, and so they can interfere with real-time processes. To see if any background processes are running (such as video panels, virus scans, and so on), press the CTRL-ALT-Delete keys simultaneously. This will display the Windows Task Manger, which shows all of the programs currently running on the computer.
Some examples of common background tasks which should be disabled: Norton utilities, RealAudio Launcher, MusicMatch Launcher.
Some background tasks, on the other hand, are essential and should be kept running. "msg32" is one example of an essential background task.
Background virus-scanning programs, in particular, are known to cause audio dropouts. If you see an anti-Virus program in the Windows Task Manager, select that program and click End Task.
The BIOS of some motherboards also includes a virus warning feature; this should be disabled, as well.
Finally, don't use any scheduled background tasks. This includes tasks which are part of the Windows Plus package, or tasks which you have scheduled yourself by using the Windows 98 Task Scheduler.
Set IDE Disk Drive Mode to DMA
Windows 98's default mode setting for IDE controllers, "PIO," can cause disk accesses to take a fair amount of CPU processing power. This can affect your system performance - including Wave drivers - even if you are using a SCSI drive for your audio recording and playback.
To avoid this problem, set all IDE drives to "DMA" mode if possible. Most IDE drives support this mode, which uses significantly less CPU processing power.
To do this:
1. Open the System Control Panel.
2. Click on the Device Manager tab.
3. Under Disk Drives, select your first IDE drive.
4. Click on the Properties button.
5. On the Settings page in the Properties dialog, select the DMA option.
6. Repeat for all of your other IDE drives, if you have more than one.
7. After you've set up all of the IDE drives in the system, restart Windows.
PCI card interaction
The OASYS PCI card relies on being able to transfer small amounts of data across the PCI bus at regular intervals, several thousand times per second. If other devices tie up the PCI bus for extended periods of time, this can prevent the OASYS PCI from completing a transfer before the next scheduled transfer. If this happens, the audio stream will be corrupted.
Some motherboard devices may also share PCI resources, even if they do not use a PCI card - and these can affect the PCI bus as well.
There are various ways that other devices can affect the PCI bus. Some possible solutions include:
1. Check the points outlined under PCI slots with shared resources, below.
2. Try lowering the acceleration settings of other devices on the PCI bus, such as graphics, video and SCSI cards. With video and graphics cards, this could also include reducing the color bit depth - for instance, try "thousands of colors" instead of "millions."
For graphics cards, you can usually set the amount of accelleration in Control Panel/System/Performance/Graphics.
3. Try swapping the OASYS PCI with other PCI cards, or simply moving OASYS PCI to another PCI slot. As always, remember to turn the computer off first! In some instances (depending upon the PCI BIOS of your PC), placing the cards in new locations will change their assigned priorities on the PCI bus, resulting in improved performance.
4. For troubleshooting purposes, you may also wish to temporarily disconnect other peripherals, including USB and Firewire devices.
5. If these steps do not help, temporarily remove all PCI cards which are not necessary to start up the computer, except for OASYS PCI. This includes extra SCSI or ATA controllers, extra video cards, other audio cards, and so on. Once you establish that the OASYS PCI is working properly, add the other cards one by one, until you find the source of the incompatibility. Once you have found the source, look in its manual and contact that company's technical support to see if they have any suggestions, such as changing settings, downloading new drivers or firmware, and so on.
Additionally, check the tips under PCI slots with shared resources, SoundBlaster Live, and Video card drivers, below.
For more information on SCSI, see the article OASYS PCI and PCI SCSI cards.
For more information on USB, see OASYS PCI and USB devices.
PCI slots with shared
resources
Motherboards may use PCI bridges to share resources between a particular PCI slot and other functions, such as built-in USB, UDMA IDE disk controllers, and bridges to additional PCI slots (if the motherboard features more than 6 PCI slots). Older motherboards may also use an AGP-to-PCI bridge, so that AGP video cards will affect the PCI bus. Your motherboard documentation should note which PCI slots share resources with other functions.
Avoid placing the OASYS PCI in these slots, since the sharing of resources can cause problems with PCI audio functions, such as distortion and audio breakups.
If your motherboard documentation does not include documentation of shared PCI resources, you may still be able to download this information from the manufacturer's website. Failing that. try swapping the slots in which your PCI cards are installed, as discussed in PCI card interaction, above.
Video card drivers
The default settings of older drivers for the Matrox Millennium or Mystique PCI video cards may interfere with digital audio. An updated driver which corrects this issue is available from the manufacturer. If you prefer to keep using an older driver, you can do the following:
1. Add the following two lines to your SYSTEM.INI file:
[mga.drv] PCIChipset=1
2. Disable the Use PowerGDI acceleration feature in the Advanced Matrox setup (Control Panel->Display Properties->MGA Settings->Advanced->Performance).
If you are using another PCI video card, try installing the standard Windows VGA driver. If the problem goes away, then there is an interaction with that card's video driver. If this is the case, contact the video card's manufacturer. They may have an updated driver or a switch similar to the Matrox above that addresses the problem.
Note: Early AGP motherboards may share PCI resources with the AGP slot - so AGP cards may affect the PCI bus. For more information, see PCI slots with shared resources.
Disable auto save (optional)
Some audio/MIDI programs include an Auto Save feature, which automatically saves your work after a set period of time. This is a cool feature, but it may interfere with real-time operation. If you are having problems with audio, and auto save is enabled, try disabling it.
Remove programs from the Windows Start Up folder
(optional)
Programs which are automatically launched at startup might continue to run as background processes, which might in turn interfere with audio functions. if you are having problems with audio, try removing all programs from the Windows Start Up folder, located at Windows/Start Menu/Programs/Start Up.
SoundBlaster Live and USB
MIDI Interface (optional)
In general, using OASYS PCI in conjunction with a SoundBlaster Live (or similar product) works perfectly well.
However, on at least one system with an OASYS PCI, a SoundBlaster Live, and a "bulk mode"-type USB interface, we found that disabling the SoundBlaster Live was necessary for reliable audio performance. This is probably due to the excessive PCI bus loading caused by bulk-mode USB interfaces; see OASYS PCI and USB for more information.
To disable the SoundBlaster Live:
1. From the Start menu, select the settings>control panel>system>device manager tab.
This shows all of the drivers installed in the system.
2. Double-click on the driver for the SoundBlaster Live.
Alternatively, you can click on the driver to hilight it, and then press the Properties button.
In the window that appears, there is a section named Device Usage.
3. Check the box labeled "Disabled in this system profile."
This will disable the driver, so that it does not interfere with the OASYS PCI's PCI bus transfers.
Set Sound Scheme to None
(optional)
If Windows is using a Sound Scheme, it may use the OASYS PCI for system sounds; this can interfere with other audio operations, and may prevent the OASYS PCI from being used by audio applications. If you are having audio problems, try setting the Windows Sound Scheme to None:
1. Open the Sounds control panel.
2. Set the Sound Scheme to None.
Disable on-board sound
chip (optional user suggestion)
One user reported difficulties with frequent crashes, which he solved by disabling the on-board sound chip in the BIOS. In general, OASYS PCI should be compatible with onboard sound chips; however, if you experience problems, disabling on-board sound may be a good thing to try. For directions on how to do so, see the documentation which came with the motherboard.
Copyright 1999-2002 Korg Inc. FAQ Version: 8/19/02