Audio Sync

hagadorn · Post by **hagadorn** » Sat Sep 02, 2006 6:35 am

I know there have been many posts about this problem and many references to various fixes but I wanted to know if my particular situation was common. I have VS10+ and the audio sync is fine after capture (Pinnacle 700-USB) and when I initially load it into VS10+. The problem seems to occur after I've multi-trimmed the file into clips. Some clips have perfect audio sync while others don't (the audio comes a couple of seconds before the video). Also, sometimes I'l watch a clip and the audio sync is fine but when I watch the same clip again, it's off! Lastly, I've found that if I go back and re-trim the original file and create the same clip, the problem is gone. How do I avoid having to watch each clip all the way through to see if I need to re-trim it?

heinz-oz · Post by **heinz-oz** » Sat Sep 02, 2006 7:43 am

Get a dedicated mpeg editor if you need to work with mpegs. If you capture mpeg and cut/trim, chances are you will lose sync. That is not a shortcoming of VS but an inheritant problem with the mpeg2 code.

jchunter · Post by **jchunter** » Sat Sep 02, 2006 3:38 pm

Hagadorn,
I assume that you are capturing analog video with the Pinnacle 700-USB, which captures to the following formats: DV, AVI, DivX, MJPEG, MPEG-1, MPEG-2, MPEG-4, RealVideo 8.

What software did you use to capture and which of the eight formats did you capture?

Please post a complete listing of the video and audio properties of the captured video. (To get a complete property listing, create a new project, insert a video clip in the Edit timeline and let Video Studio set Project Properties to match.)

hagadorn · Post by **hagadorn** » Sat Sep 02, 2006 5:50 pm

Heinz-oz, what is an mpeg editor and how do I get one?

I am using Pinnacle Studio Plus 10.5 to capture. Here are the properties:

NTSC drop frame (29.97 fps)
MPEG files
24 bits, 720 x 480, 29.97 fps
(DVD-NTSC), 4:3
Video data rate: Variable (Max. 8000 kbps)
Audio data rate: 224 kbps
MPEG audio layer 2, 48 KHz, Stereo

In VS, I always match the project properties although Pinnacle doesn't tell me if it's upper field first, otherwise everything else matches.

Would it make a difference if I captured in AVI? The files are so much bigger?

Like I said, if I go back and re-trim the clip, the audio sync problem is often not there anymore, so maybe I should just check each clip before making the final video file and re-trim if necessary? Question: if the audio sync is fine in one part of a clip (trimmed video), can I assume it is fine throughout the whole clip? I don't want to have to watch every minute of every clip!

jchunter · Post by **jchunter** » Sat Sep 02, 2006 6:51 pm

Hagadorn,
Your captured file properties look fine but do not specify the the Field Order property, which should be Upper Field First for analog video. Video Studio should have reported the Field Order Property, when you inserted into the empty timeline. Please try again and read the properties from the menu File/Project Properties. Double check the Field Order by pressing the Edit button and then opening the General Tab.

Mpeg2 does not inherently cause audio/video sync problems but bugs in its implementation can. In your case, the Pinnacle 700 is converting analog video to digital and then encoding in Mpeg2 format. That could be a potential source of the problem.

I have not experienced any A/V sync problems when editing mpeg2 in versions 9 or 10+. BTW, I use the scissors control (under the preview window) for most of my edits.

hagadorn · Post by **hagadorn** » Sat Sep 02, 2006 8:51 pm

Like I said, Pinnacle does not show field order but I set it to upper field in VS.

Can I just do a simple fix by checking each clip before making the final video file and re-trimming if necessary? If the audio sync is fine in one part of a clip (trimmed video), can I assume it is fine throughout the whole clip?

jchunter · Post by **jchunter** » Sat Sep 02, 2006 10:47 pm

Hagadorn,
You can't change field order just by switching project properties in
video Studio. You have to find out which field order Pinnacle encoded when it captured the video. This will govern your Field Order settings for the remainder of the Edit process.

To find out the field order do the following
1. open Video Studio
2. Place one of your captured video files in the Edit timeline.
3. A dialog box will open that asks if you want Video Studio to copy the properties from the video file to the Project Propertties. Press the "Yes" button.
4. Open the FILE menu,
5. Select Project Properties
6. Press the EDIT button
7. Click on the General Tab
8. Read the Field order property that is displayed

Post by **Ken Berry** » Sat Sep 02, 2006 11:41 pm

John, wouldn't it be just as easy if she were to open VS, Insert a file in the Library pane, right click on it and see what Properties says about Field Order?

hagadorn · Post by **hagadorn** » Sun Sep 03, 2006 8:57 am

I looked at the properties of the captured video files and they were upper field first order, but I was suripsed to see that the video data rate was max 8800 even though I set it to 8000!

maddrummer3301 · Post by **maddrummer3301** » Sun Sep 03, 2006 1:25 pm

rcurzon · Post by **rcurzon** » Sun Sep 03, 2006 2:22 pm

You'd be better to eliminate the problem at the source... which you are working on already.

BUT If you are stuck with some out of sync MPEG clips already, or just want a short path to fix them... VStudio can help.

Providing that the audio gap is essentially constant for the duration of a clip...

Right click on the clip in the timeline, and select Split Audio. The audio goes to a separate track, and you can slide it til it's in sync.

jchunter · Post by **jchunter** » Sun Sep 03, 2006 3:37 pm

Hagadorn,
OK! We have established that the field properties are correct in the captured video. I would not be concerned about a video bitrate value of 8800Kbps because it is within acceptable limits.

I think it is still way too soon to "shotgun" this problem. Womble, Virtual Dub, etc. are poorly documented, very difficult to master and can do a lot of damage if not used correctly...

IMHO, the next thing to look at is the very strange situation of OOOS "Occacionally Out Of Sync" in the same clip. Are the playback methods the same? Does this really happen? Try Media Player Classic for reliable playback - I find that Video Studio and Windows Media Player are less reliable for video file playback

Splitting the audio and manually resynchronizing would be difficult if OOS is not repeatable.

BTW, Ken, the reason for reading properties the long way was that I have seen cases in Video Studio where Frame-Based field order was displayed as a blank, when using the right-mouse-on-clip method. I also have long suspected that new users are not aware of the EDIT button in the Properties window, which is essential for controlling the Project Properties.