Have you tried converting a simple avi or mpeg and seeing if that goes out of sync? I've honestly never had any syncing issues with Xilisoft so I don't know how well I can help..
Yea I tried converting Bleach to DPG and the sound is in sync. I then converted my RMVB file to AVI, then tested out the AVI file. The sound was still in sync. However I then converted that file to DPG and again, the sound slowly got out of sync.
I emailed Xilisoft support and their response:
QUOTEDear Customer,
Please modify “Frame Rate” on the right panel of the main interface. The default setting of this item is “Auto”. Please enter a concrete number for it to have a try. I think you can try following numbers: 15, 23, 29.97,50 and 60 .Generally, one of them will work. Please highlight the item which you want to convert by our program before modifying anything. Please press “Enter “after you input the number.
Also, you can try on some other number which seems to be closer. Generally, if the audio is a bit earlier than the video, you need to adjust the frame rate to higher value to speed up the video, if the video is a bit earlier then the audio, please set the frame rate to a smaller value to have a try.
If you still have any questions, please do not hesitate to e-mail me again.