TechNote (Archived)

Windows Issues

My screen isn't updating as it should and some images or program icons are not displaying or appear in the wrong place. Some screen objects don't move as they are supposed to. I also get General Protection Faults in modules called GDI.EXE, USER.EXE, or one that ends in .DRV. What's going wrong?

You may have a problem with your display driver. Use the Windows Setup program to change your display driver to the generic driver called "VGA". Restart Windows to have your changes take effect. If the errors don't occur after you switch drivers, your display driver may need updating. Contact the graphics card manufacturer to see if there is an updated Windows display driver for your graphics card. Manufacturers frequently update their drivers.

I have sound imported in my application, but when I play it, why don't I hear any sound?

Check the volume control on the sound card. Use the sound mixer application that came with your sound card to check and adjust the volume.

Make sure that the speakers are correctly connected to the proper jack on the sound card.

Make sure that you've installed the appropriate Windows and MCI sound drivers, using the Drivers control panel.

Try playing a sound using Media Player (in the Accessories program group in Windows' Program Manager). If you can't a play a sound in Media Player, then you won't be able to play it in your multimedia application.

Make sure that you don't have another application open that's using the sound device.

If you still can't hear any sound, refer to the manual that came with your sound card.

How can I improve the performance of my multimedia application? I'm using a lot of graphics.

There are several ways you can improve the performance of your multimedia application, especially if you use a lot of graphics. Refer to your application's documentation for specific guidelines, but here are some general tips:

Create 8-bit color graphics instead of 24-bit color graphics whenever possible. 24-bit graphics are three times larger than 8-bit graphics. Smaller graphics animate more quickly and occupy less memory than large images, so the computer can process them faster.
To avoid undesirable palette shifts, display 8-bit images in 16-bit or 24-bit display mode.
Preload large graphics to have them readily available in memory.
In Windows 3.1, make sure that your virtual memory swap file is set to permanent and that you're using a disk cache program such as SMARTDRV.EXE. Windows 95 normally manages these settings for you, you can check its settings if you choose Start > Settings > Control Panel > System > Performance > Advanced settings.
VESA local bus or PCI local bus video offers additional speed improvements for displaying large graphics and complex animations. If possible, use a PC that supports VESA local bus or PCI local bus video.

How can I improve the performance of my multimedia application when I'm using sound?

Here are some general tips:

Keep sound segments as short as possible by breaking them into short durations. For example, if your production uses narration, break the narration into small files containing individual phrases.
To keep sound file sizes as small as possible, sample sounds at the lowest acceptable sample rate.
Unless you have a specific need for stereo narration, record narration in mono sound.

I have a 5-second mono 8-bit sound that's sampled at 11kHz. How large is it going to be?

55K. To determine the approximate size of a sound, you can use the formula:

file size (Kbytes) = (number of seconds) x (sample rate in kHz)

A 1-second 8-bit, 11kHz mono sound would be 11 kilobytes, and the same sound sampled at 22kHz would be 22 kilobytes. A 1-second 16-bit, 44kHz mono sound would be 88 kilobytes. For multiple channels, such as stereo, just multiply the value by the number of channels.

I'm seeing strange color shifts in my production. What's happening?

Check to see if you are running in 8-bit (256-color) display mode. When you play your production in 8-bit mode, your computer must select colors from one 256-color palette. When you change palettes, the colors of the objects on the screen will shift to remap to the new palette.

To avoid undesirable color shifts, make sure that all the 8-bit images in your production share a common palette. You can instead change your display to 16-bit (also known as "high-color") or 24-bit (also known as "true color") mode; however, this affects performance, and if you're distributing your application keep in mind there are a few users out there whose graphics cards don't have high- or true-color capability.

What do I need to include when distributing my multimedia productions?

At the very least, you need to distribute the production that you created, along with the run-time program or executable, if your production wasn't saved with the executable contained within it.

You also need to distribute any external files needed by your production, such as external movies, fonts, and external graphic and sound files. If your production requires any special drivers, you need to include those as well. If you're using QuickTime for Windows or Video for Windows, you need to distribute those too, since the delivery machine may not have these already installed. Be sure that you contact the appropriate vendor for the licensing requirements for distributing their products.

What's an important step I should take before distributing my production?

Since computer configurations can vary, test your production on different computers to make sure that it plays consistently on all of them. Be sure to test your production on the computer configuration you intend to deliver on. If performance on the intended delivery computer is too poor, you can make changes to improve playback before you distribute your production. Make sure that you have enough memory and hard disk space on all delivery machines.

Make sure all delivery computers use the same monitor resolution (for example, 640x480) as the authoring computer. If you play back a production on a computer that is configured with a lower display resolution than the authoring computer, objects such as graphics and text will appear larger because of the different horizontal and vertical pixel count. If you play back a production on a computer that is configured with a display monitor resolution higher than the authoring computer, objects such as text and graphics will appear compressed.

What should I keep in mind when playing my multimedia production over a local-area network?

There are a number of factors that affect performance when playing your production over a network.

The overall efficiency of the network is very important. Multimedia demands a lot of bandwidth, and it's important that your network is capable of handling it.

The number of users on the network is also a factor. If there are a large number of users on the network, you can expect that the response time from the network will decrease.

Just as if you weren't on the network, the speed and memory capacity of the playback machine is important. More is always better.

Again, similar to non-networked machines, the number and size of graphics, sounds, and movies used in the production should also be a consideration.

Finally, the location of the executable production file is important. For best performance, keep the executable or program file on the playback machine, so that each time the program needs a code segment, it can get it from the local machine and not the network server. Any external data files you have can be placed on the network server.

What software can I use to distribute multimedia productions to other computers?

There are a good number of installation programs available which you can use to distribute your production to other computers. Installers usually compress your files on one or more diskettes for easy installation. Install Shield from Sterling Software (800-3-SHIELD), INSTALIT from Helpful Programs, Inc. (800-448-4154), and EDI Installer (available on-line) are examples of installation programs. PKZip from PKWare is an example of a compression program that can help you distribute your products. You can also create DOS batch files to "install" software.