Problem with avi audio-video synchronization

I have an experiment that at various intervals presents video/audio instructions (.avi format). The instructions files run from 9mb to 25 mb in size. The problem is that the video begins lagging behind the audio as the clip plays, and as the experiment goes on, this gets more pronounced. I have the memory set to load the files before the experiment begins in the “options” menu, but this does not solve the problem. Any ideas on why this is happening?


If you play the file in another movie player, does the audio still lag? This functionality is handled by DirectX, so this is likely to be an issue either with the file itself or with the codec. If you haven’t already, try installing the latest version of DivX, and see if that makes a difference.

If you’re on the Mac, this is handled by QuickTime. Again, installing DivX may help.

Checking. . .

The files don’t lag in windows media player or real player. I’ll install your fix and let you know what happens shortly.



DivX not helpful

The DivX installation did not solve the synchronization problem. Oddly, the experiment seems to have been affected, as the program freezes my computer if I run it from the first instruction. I must bypass the first block to get the experiment to run now.

The files still play fine in other players.

It freezes your computer? Do you mean you can’t alt-tab to another program, ctrl-alt-delete doesn’t do anything, the mouse doesn’t move, and the caps-lock key on your keyboard no longer lights and dims when you press it?

What version of Windows are you using? What processor does your machine have? Is it multi-core? Does it support hyperthreading? SuperLab isn’t particularly nice to background processes, and in this context, movies and audio count as background processes, so if you don’t have at least a hyperthreading processor, movies and audio will be starved for processor time.

It freezes SuperLab

Sorry, it freezes superlab, not windows. My mistake.

I have a dell Inspiron 9300 with 1.5 gigs of RAM. Intel® Pentium® M processor 1.86GHz. Version x86 Family 6 Model 13 Stepping 8. Speed 1862 mhz. XP Professional, Version 5.1.2600. Service pack 2. Bios Version Dell Inc. A04 .

I don’t know if it’s multicore or supports hyperthreading.

According to Wikipedia, that’s a single-core processor that does NOT support hyper-threading.

Note that a 30-second google search seems to imply that your laptop can be upgraded to a core duo, but don’t take my word for it.

This is likely the source of your issues. Do you have any other machines on which you could try this, or could you send the experiment to me to test at my end?

The problem is . . .

Unfortunately, even if I upgrade my computer, my colleagues computers may not have such capability. Unless I can re-shoot the instructions in another format, such as MPG to solve the problem, it won’t be feasible to widely distribute the experiment to others using SuperLab, as their processors would have the same problem. I had no idea that this issue existed.

Thanks for the offer to look at the experiment. I’ll get back to you, but I must first check to see if my computer is simply outdated, and everyone now has better capabilities. If everyone I work with at the University can’t run these files on their computers, SuperLab won’t be useable with our design.

New computer


A new processor did the trick. Thanks.