Problems Playing AVI in VirtualDub

[brlase12]

I recently downloaded VirtualDub and tried to preview an AVI I had captured using Pinnacle Studio DV 7. The AVI plays fine in Windows Media Player but when I tried to watch it in VirtualDub, the picture paused in and out and the audio cut in and out in synch with the pauses in the picture - about every second. My computer specs are:
Pentium III
450MHTZ
256MB RAM
Western Digital 40GB 7200rpm Hard Drive
Windows 98SE
Pinnacle Firewire capture card
Other cards unknown

Anyone have an idea of what the problem may be?
I am hoping it is just some settings within VirtualDub.
(I also tried to apply a filter and save the AVI and the resulting AVI still played the same way.)I would really appreciate any feedback. Thanks.

[brlase12]

Anyone...

I hear really good things about VirtualDub filters and I really want to try them, but I can't until I get through my problem stated above. I am determined to get this to work so I would really appreciated any feedback. I have tried changing numerous settings within vdub but still getting choppy sound and the video seems to be in slow motion while the audio is cutting in and out. The AVI file plays and looks great in every viewing software I have tried _Windows media player, realplayer, ...). It also plays good in Pinnacle Studio DV 7 and I can convert to MPEG-1 using TMPGEnc without any problems. I also downloaded the sample NTSC VCD of Spaceballs from this website and it plays great in VirtualDub (I know that it is a MPEG-1 file and not an AVI).
More info:
I captured from my mini DV videocamera (Sony DCR-TRV11) using Pinnacle firewire card at 720x480, 29.97fps, Pinnacle's DV Video Encoder (default setting for capture).

Is there anyone who can help or has any suggestions? I would appreciate anything I can get at this point. Thanks to everyone who has taken the time to read this.

[mpack]

Uh.. as far as I know this is normal behaviour in VirtualDUB. VDub is designed as a filtering/dubbing tool, not a media player. Even in "preview" mode it is still using all those filters (it just isn't writing the result to disk), and there's no way it can do that and still keep up with real time. So, instead it dubs about a seconds worth and plays that back at pretty close to real time. A reasonable compromise in my book.

[mikewg]

Honestly, I don't use filters and VirtualDub plays my videos perfectly.

If you want to test it... cut a clip of your AVI in VirtualDub and save it as it's own AVI. Then play that new AVI in Media Player and see if VirtualDub messed up your file.

[brlase12]

Thanks for the suggestions! To test it, I applied a simple brightness filter and saved the AVI. After it was rendered, I opened it with Windows Media player and it played exactly the way it did in Virtualdub - extremely choppy. I do not understand what the problem could be. I open vitualDub, call up the file and without doing anything, I press the play button to view it first thing (without telling it to render) - so that I can decide what filters are needed and it is choppy. I wish I knew why it plays perfect in media player but not in virtualDub. This applies to all AVI's I have tried in VDub. So, I guess I am stuck - I do not know where to go from here. I really want to give VDub a chance. Is there another freeware out there that is very similar to VDub that I can try? Again - I really appreciate the help.

[brlase12]

OK...I have really been testing to figure out what the problem is. I decided to try to load every AVI I have in VDub to see which ones will play good and which ones won't. Pinnacle automatically saves a low resolution AVI file of every capture in its "Captured Video" folder - these 180x120 AVI files work great with VDub, but the 720x480 files do not. So I encoded an AVI file using Studio DV 7 with a size of 352x480 and it worked and looked great in VDub. So I decided to take a look around VDub for any settings that would affect this problem. At one point, I ended up in the Auxiliary Setup box. I entered the "Benchmark" box ("Test Hard Disk Video Capture Performance&quot

First Test Settings:
drive to test - C: Hard Disk []
disk buffer (KB) - 1024 (Default)
disable windows buffering - not checked
frame size - 720x480
frame rate (fps) - 29.97
frame count - 200
frame buffers - 50
data rate (KB/s) - 20230 (default and unchangable)
>Start Test>>>>"Test Failed - Frames Were Dropped"

So I try the test again with the same settings except I checked the "Disable Windows Buffering" box
>Start Test>>>"Test Passed - No Frames Dropped"

What is this telling me?
What is "Windows Buffering"?
How do I permanently disable this so I can capture with no dropped frames?
Could this be the problem I have been having playing large AVI files in VDub?
Does VDub have trouble working with AVI files on which frames were dropped? (These files play fine in WMP)

I apologize if I am a bit overwhelming with questions but I am trying to understand how all of this works and comes together.
Any Suggestions/Explanations?

[mpack]

I don't know for sure what VirtualDUB is referring to, but I would guess that its talking about your disk cache.

Windows has a notoriously troublesome feature called "write behind caching" in which it postpones and queues up a bunch of disk writes so it can do it all in one burst in cpu idle time.

Trouble is, during a long video capture there is often little or no idle time, so as soon as that big cache fills up (which happens VERY quickly during hi res capture) it goes into panic mode in order to flush the cache. This interrupts your capture for much longer than would have been the case for several smaller disk writes. The result is usually dropped frames, though your capture software should have given you some indication of this.

There are several newbie guides floating around the web on the subject of optimising your PC for video capture - including how to tweak your cache and virtual memory settings. Perhaps you should do a search.

[brlase12]

Thank you so much for your suggestions! I will definitely do some searches and try to figure out how to improve my video capture capability. I will post anything I come up with that works to hopefully help any other users who encounter the same problem. Thanks again.

If anyone else has anything to add - please do.
Thanks!