Audio - Video sync problem

[Roberto]

Hello,

with VS X3 I experienced a bothering trouble and I wish to know if anybody can help.
The task is to sync a .mts video, taken with my Panasonic SD20 camcorder, and a .wav audio file, recorded witha Zoom digital recorder.
The sync is pretty easy, but I noticed that after some minutes the two tracks drift, that is, the audio and video move out of sync.
I checked the project options, actually they should be correct as once the video file is inserted at the beginning, VS should change the settings to abide the video specs.
If I use a simple VGA-resolution AVI file, like the one created by my old Canon POwershot S2-IS camera, the video-audio sync is ok, no drifting.
Any suggestions ?

[DVDDoug]

If the drift is constant, it might be that the clock (oscillator) in the Zoom or the camera is a bit "off", or in any case, they don't exactly match. In some cases these clock mis-matches can be severe and it's not that uncommon for musicians to record on one system and play-back on another and notice a pitch-shift.

Or, there could be something about the MTS file that's giving Video Studio trouble.

Since you're using the Zoom, I assume you have an audio editor. You can change the speed of the WAV slightly with the audio editor. You might have to break-up the audio into a few shorter tracks and re-sync it every so-often. It's a royal pain, but it might be the only solution (other than trying-out different video editing software ).

Assuming a slight pitch-shift is not a problem, it's best to do a simple (re-sampling) speed change and allow the pitch to shift too. If you change speed and maintain the original pitch, this requires more processing (FFT) and you can get artifacts.

[Roberto]

Thanks.
Actually because my audio takes are about 5 minutes maximum, the audio-video drift is not that big, even though still bothering me because at the beginning I have to move a bit ahead the audio part so that at the end it will not be too much delayed.
But I really wonder if this is a HW ( camcorder and digital recorder ) problem or SW ( VS X3 ) problem.
When I find somebody with another NLE software, I will rebuild the project there and check if the drift is still there or not...

[Trevor Andrew]

Hi

Using Video Studio..............
You could try altering the playback speed of the audio file.
That would either stretch or compress the audio length.