Virtual Dub 10min sequences slightly asynchron 24,86fps...

[Weef]

Hi, I'm just restoring an elder cartoon, and I'm working on it with Virtual Dub.
My procedure is to cut the original file into 10min sequences, make my own cuts and then assemble it back into a 10min file.
But here my problem.
Audio and video comes from the same source and run at 25fps when I have my new assembled file I need to set the fps to 24,86 - 25,02fps to get both tracks synchron again! Is that the general case? What can I do to get exactly 25fps?

[jagabo]

The frame rate shouldn't change at all in the cut/paste scenario you're describing. Does your source have VBR audio? If so, I would convert it to CBR.

[Weef]

Hmm, no, I think it is CBR, it's steady, Virtual Dub isn't asking me to convert it...but it's the original AC3 audio track...

[jagabo]

Are you changing the length of the video? Check the number of frames in the original and the final cut.

[Weef]

I'm pretty certain, that's not happening...I cut them with 25fps and once new edited and arraged I compress them with 25fps...yeah well, actually that is where the problem appears when I want to make the final output I suddenly need to change the fps to 24,86 / no rather 24,88fps to make it look synchron...I don't know how this happens, I don't have doubled frames..

[jagabo]

Is the frame count exactly the same? Having to change the frame rate to 24.88 implies you lost about 0.5 percent of the frames in your editing.

[Weef]

Just yet I'm not able to reproduce that, I had to delete the uncompressed files to make room for next five 10min sequences.
And the 24,88fps matter only appears at the end of my editing when all single handed edited files come together as one. All all steps before I'm only using 25fps...but suddenly I have to use 24,88fps to get audio and image synchron again o.o

[Weef]

WTH...I just have noticed that Virtual Dub offers me the weird option to synchronize the audio with the video - but with 192.892fps...and in the uncompressed master file....hmmm something certainly went wrong, what, we may never know..hmm have to check this out next time

[jagabo]

The "Sync To Audio" option only effects preview within VirtualDub.

[DarrellS]

You're problem is probably the ac3 audio. I'd fix the audio skew with audio interleave (look in file information to find the skew) and convert the video to AVI first before cutting into seperate clips. When cutting the clips, use smart render so you don't recode.

I use DVDDecrypter in IFO mode with no splitting to get a single VOB or you can use VOB2MPG. This will help with sync issues also.

Could you post a mediainfo text file from the original source file?

[Weef]

Uuuuh >.>...ok
I checked the file I'm just working on instead of 13538 for (25fps x 9min+1.5sec) I get 13864 frames for the same length in the assembled file... so there are 2,4% more picture than there should be....I don't know what's wrong with VD!

[Weef]

@DarrellS
Most of the things you say I already did.
The "master file" is an AVI and I cut it in seperate pieces before they come back together...