Lowering volume using Enhance Video messes up audio synch

jedi-jae · Post by **jedi-jae** » Thu Sep 01, 2005 7:34 am

After some experimentation trying to figure out why my DVD's were suffering from sound synch problems, I determined the following...

I found that if I used the Enhance Movie option to lower the volume of the video it threw it out of synch. I've no idea why, but I wondered if it was because it was a "virtual" change to the movie and was proving so resource hungry that my PC couldn't keep the image and sound together.

The video in question was about an hour long, but the sound was slipping only 20 minutes into it.

Anyway, I've lowered the "Line In" level to reduce the volume that way; I can now edit, add chapters and menus then burn to DVD and the results are perfect!

So: Ulead, why does this happen, is it a PC resource issue?

maddrummer3301 · Post by **maddrummer3301** » Thu Sep 01, 2005 10:23 am

What version of MovieFactory are you using.

MD

jedi-jae · Post by **jedi-jae** » Thu Sep 01, 2005 10:27 am

Sorry, MF4

DVDDoug · Post by **DVDDoug** » Thu Sep 01, 2005 10:42 pm

...is it a PC resource issue?

No. Any digital processing is just "number crunching". As long as you don't get an "out of memory" error, processing power should only affect the amount of time it takes to process. (The lack of processing power can be an issue for real-time analog capture, and for playback.)

I suspect a corrupt video file.

Because the audio & video are (usually) multiplexed together, corruption or a glitch won't cause sync problems until the audio & video are de-multiplexed and re-multiplexed. In order to process the audio, tha A/V have to be de-multiplexed.

De-multiplexing & remultiplexing is usually required during rendering too. So, it is very common for everything to look (and sound) OK 'till the DVD is burned, and then sync problems suddenly appear.

jedi-jae · Post by **jedi-jae** » Fri Sep 02, 2005 8:57 am

No, sorry to clarify, the sound goes off synch before I burn to DVD.

I capture a video to my PC using MF4 - sound and image are in synch.

I edit the video and add chapter points - sound and image are in synch.

The video is a bit loud, so I go to Enhance Video and use the Audio option to lower the volume - sound is now out of synch with image, this is in preview mode, on the first screen of the process where I can jump to any point and press play to watch the video.

If I continue the process, add a menu then go to the "proper" preview screen where you have the remote control to jump chapter and test everything, the sound and image are out of synch.

It is the volume adjust option in the Enhance Video section that causes the synchronisation to break.

jedi-jae · Post by **jedi-jae** » Thu Sep 15, 2005 10:21 am

An update: having installed the latest MF patch the volume problem seems to have gone.

I need to experiment a bit more using longer videos, the one that wasn't affected by my lowering the volume in the Enhance Video panel was only 15 minutes long, but it's looking hopeful!