Video and audio gradually go out of sync?

[BuriedInSmoke81]

Ok here's the deal....
I have a dvd of a concert which I'd like to replace the audio on with a far better audio recording I also have of the same show.Now Ive done 6 or 7 of these projects before that have turned out fantastic,but I've never encountered this problem of the audio going out of sync halfway through each song.

However none of the other projects I've done were transfered from vhs,they were all digital video recordings,would this have something to do with it?Anyway I'm doing all of my syncing in vegas 7..Everything is ready to go,I just cant figure this out and its thrown me for a loop...Any help would be greatly appreciated!
Thank You!

[themaster1]

Fixing such a thing perfectly is always a pain.How about recapturing?

[BuriedInSmoke81]

Fixing such a thing perfectly is always a pain.How about recapturing?

I dont have the original vhs tape,I got it from someone who had already transfered it to dvd...I assume thats what you mean?I just dont understand why or how it could be in sync perfectly fine at the begining and by the end its completley out of whack

[SLK001]

I dont have the original vhs tape,I got it from someone who had already transfered it to dvd...I assume thats what you mean?I just dont understand why or how it could be in sync perfectly fine at the begining and by the end its completley out of whack

This is because VHS is far, far from perfect. But your digital recordings are as close to perfect as they can get. Your best be would be to stretch the audio to fit the video. This can be done either with or without the preservation of pitch.

An analog recording can be off frequency (fps wise) and be playable. A digital recording of this will record at near perfect frequency, thus throwing things way off.

[BuriedInSmoke81]

I dont have the original vhs tape,I got it from someone who had already transfered it to dvd...I assume thats what you mean?I just dont understand why or how it could be in sync perfectly fine at the begining and by the end its completley out of whack

This is because VHS is far, far from perfect. But your digital recordings are as close to perfect as they can get. Your best be would be to stretch the audio to fit the video. This can be done either with or without the preservation of pitch.

An analog recording can be off frequency (fps wise) and be playable. A digital recording of this will record at near perfect frequency, thus throwing things way off.

If I stretch it it will be out of sync at the begining,ive synced it towards the end of the song,but then the begining is messed up....I guess Im just screwed on this one eh?

[SLK001]

No, I said "stretch" the audio, not shift the start time. If your video is 44:22:11 (m:s:f) long and your audio is 44:19:03 long, then you need to stretch your audio to 44:22:11, or increase its length 100.1228%.

[BuriedInSmoke81]

Video is 1:41:45 and the audio recording is 1:11:46 there's a lot of banter inbetween songs that was cut out of the audio recording,and the opening intro is cut on the audio recording.Thats not a problem I can work my way around that and either cut the video I dont need or leave the original audio in place for those parts.

If I try to stretch the audio in vegas to make it longer it loops around to the previous audio track,after ive passed the point where it originally started.If thats what youre reffering to.If not...is there a program or something that would allow me to do this?

Thanks for the help!

[SLK001]

Video is 1:41:45 and the audio recording is 1:11:46...

In this case, you're going to have to do the stretch in parts. You'll need a good audio editor to do this. I use Adobe Audition for things like this, but others will also work. You'll be using the built-in studio track editor along with the normal wav editor. Just stretch (or compress) the particular audio track to fit into the slot that the audio on the original take resides. Then, using the studio editor, blank out the original and enable the new. If done properly, it will be almost seamless.

These are advanced techniques and I'm getting the feeling that this is beyond your capabilities.

[BuriedInSmoke81]

Video is 1:41:45 and the audio recording is 1:11:46...

In this case, you're going to have to do the stretch in parts. You'll need a good audio editor to do this. I use Adobe Audition for things like this, but others will also work. You'll be using the built-in studio track editor along with the normal wav editor. Just stretch (or compress) the particular audio track to fit into the slot that the audio on the original take resides. Then, using the studio editor, blank out the original and enable the new. If done properly, it will be almost seamless.

These are advanced techniques and I'm getting the feeling that this is beyond your capabilities.

Nothing is beyond my capabilities man 8) it just might take me a few hundred tries to get it right,but thats how you really learn something...isnt it?Thats what Im after man,knowledge....and the RIGHT method for this scenario.

I really appreciate your input,are there any other programs besides adobe that might enable the process of doing this,I dont exactly have $400 to drop on adobe right now?It's absolutely ridiculous what these companies charge for computer programs and expect your average joe to not pirate them.They dig their own grave.

Is there a way perhaps I could change or tweak the fps in order to coincide with the audio?

[poisondeathray]

From your description, it sounds like you have to process it in segments.

I don't think you want to alter/stretch/shrink either the audio or video because it won't match - you said there are gaps in the audio. Doing so will just make the good matching parts go out of sync

There is no automated software that will do this. You will probably have to use software with a timeline to line up the audio & video segments; and either cut video, or add "filler audio" to fill the gaps. Cutting video is much easier IMO. This is tough to do, and even tougher with just freeware. Do you have a rough idea of how many matching "segments" you have?

[BuriedInSmoke81]

From your description, it sounds like you have to process it in segments.

I don't think you want to alter/stretch/shrink either the audio or video because it won't match - you said there are gaps in the audio. Doing so will just make the good matching parts go out of sync

There is no automated software that will do this. You will probably have to use software with a timeline to line up the audio & video segments; and either cut video, or add "filler audio" to fill the gaps. Cutting video is much easier IMO. This is tough to do, and even tougher with just freeware. Do you have a rough idea of how many matching "segments" you have?

No idea man...Like I said theres plenty of video I can cut,but Id usually do that in tmpgenc when im ready to author it and make chapter break etc.

[guns1inger]

In Vegas you can either hold down the ctrl key when you drag, so actually stretch the audio, not loop it, or if you have Sound Forge installed, use the Time Stretch filter to work with greater accuracy. Audacity also has a time stretch filter, but you will have to export the audio, stretch it and then bring it back into Vegas.

The person who did the original transfer needed to use a Time Base Corrector to get a clean recording.

[BuriedInSmoke81]

Thanks guns1inger...I'll give that a shot.

[hech54]

This whole thing sounds like a job for.....someone else.


Good luck man.

[tinker]

Your Audio is 30 min shorter than video. Stretching it that much will make it totally useless.
You mentioned that your good audio has parts cut out. In that case what you will have to do is to split each song and place it under video section which it belongs, stretch it there to match. Rest of video without sound can be cut out or left with old track using transitions between so it sounds like it belongs.
In any case it will be lots of work.

[greymalkin]

Your Audio is 30 min shorter than video. Stretching it that much will make it totally useless.In any case it will be lots of work.

read his posts again..there is additional talking/etc. on the video that is not included in the better audio.

[BuriedInSmoke81]

This whole thing sounds like a job for.....someone else.


Good luck man.

Im begining to think that myself,I found a formula to calculate the stretch needed,on a guide here somewhere and I managed(after racking my brain for 2 hours w/math)to do the stretch but its so slow....it's totally f'ed up.

tinker...the audio is already cut into 16 wav. tracks,before I did the stretch I rendered the entire thing as one big wav. file in vegas.I tried to stretch each one seperately in vegas,but it seemed like I was just playing with myself...Perhaps I'll give it another go,but I want sure which way to stretch it....from the begining...or stretch from the end of the track?

Thanks guys,I really appreciate your input!I'll make a lot of people happy if I can pull this off,so I ain't givin up yet! :P

[2Bdecided]

If it helps, I'll tell you what I would do...

Start with the video. It has its own poor quality audio in-sync, yes? If not, you have to find some way of getting the source audio in-sync with the source video! Assuming it's in-sync...

Do whatever you want to do with the video in your NLE. Maybe there are some cuts? Fades at the start and end? Do all those first. Then export the "final" result - video and audio.

Then pull that reference "bad" audio into a proper audio editor, and work in there. I use Cool Edit Pro - it's now called Adobe Audition. Use the multi-track mode.

Put the reference audio in the top track. DO NOT CUT, PASTE, STRETCH, etc that reference audio. You can filter, EQ, fade etc all you want.

Drop the other pieces of audio (from a CD?) into other tracks in the multi-track. If they're at different sample rates, Cool Edit Pro will convert them automatically.

Drag the new tracks so the start of each one is in sync with the reference audio. Then measure the difference in sync at the end. Calculate what the duration of each track needs to be to make it all in sync (it's the current length, plus the difference). Then drop into track mode and set the duration using time stretch - "low quality" is more than good enough and quite fast.

You might find that the percentage stretch (which is automatically shown for you when you enter the new length) is the same for all the tracks, or you might not. If it is, it makes this quite easy - you only have to measure one track, and then adjust all of them by the same percentage. I'd measure them all if you're not sure.

Now everything is in sync together in the multi-track.

Cross fade the "bad" audio and re-timed good audio in the multi-track view. When happy, mix the whole lot down to a new stereo wave file.


If you want to take it back into your NLE, do so, replacing the original audio with your new mixdown.

Alternatively, if you encode using another application, take the video (that you saved at the start) and the new audio and feed them both into your encoding package.

If you didn't mess anything up, then...
1. the original audio was in sync with the original video
2. the new audio was in sync with the original audio, and therefore
3. the new audio will be in sync with the original video!


Why do I do it this way? Because I know how to use Cool Edit Pro very well, and trust it. I'm not confident enough with any NLE to do this kind of audio work as quickly as I can in Cool Edit Pro.

It's not quick, but you're talking a couple of hours, rather than a couple of days!

Hope this helps.

Cheers,
David.

[lordsmurf]

This was caused by dropped frames. The video frames are missing, but the audio was constant.

There is really not much that can be done, it will always be less than ideal.

The person who did the transfer was a moron, and it needs to be redone.

[hech54]

I think what happened was a better audio source was
found for the show....but that audio was edited down
to make it more listenable.
I ran across the same scenario a few years ago but
in reverse. Someone came across a video to a concert
that was played on Westwood One radio. The Westwood One
audio has been floating around for many years and is really good
quality....nobody knew about the matching video until many years
later and there were major edits done to the audio like cutting out
talking and band intros.

[2Bdecided]

This was caused by dropped frames. The video frames are missing, but the audio was constant.

How do you know?

If I found two independently recorded audio sources for the same event, I wouldn't expect them to be in sync.

Why does the fact that one of these sources also has video cause you to believe that there's some fault?

Two clocks, running independently, won't stay in sync.

That's said, I'm not 100% clear what the OP is saying, but it sounds like he has a VHS (now on DVD) and a CD - and the CD won't sync with the DVD. This doesn't imply a fault. He's very lucky that he hasn't faced this before - independent digital clocks don't stay in sync either!

Cheers,
David.

[BuriedInSmoke81]

[/quote]That's said, I'm not 100% clear what the OP is saying, but it sounds like he has a VHS (now on DVD) and a CD - and the CD won't sync with the DVD. This doesn't imply a fault. He's very lucky that he hasn't faced this before - independent digital clocks don't stay in sync either!

Cheers,
David.[/quote]

Thats exactly what it is David,someone transfered the show from a vhs,being it was recorded in 98 had to be vhs,transfered it to dvd(this is the video I have)when I got the dvd I remembered I also had a soundboard recording of the same show on a cd-r,which as you could imagine is far superior to the audio on the dvd....Not that the audio on the dvd is unlistenable,I just wanted to make a really nice version of it.

I tried stretching each song in vegas,but when I would get it to sync it would always end up going out again 30 secs. later.

I'll try your method with the audio David,I dont have Cool Edit though I'm using Soundforge.

Thanks.

[BuriedInSmoke81]

Thanks for your help guys,but Im scrapping this...Its not worth the frustration,lord knows I have enough as it is.I may come back to it down the road,but I have other things I wanna get done...That I know I can get done!All the help is most appreciated and now I know where to come when I have a question about anything like this!!Thanks

[lordsmurf]

If I found two independently recorded audio sources for the same event, I wouldn't expect them to be in sync.

I'm sorry, but that doesn't make any sense at all. Time is a constant, cameras cannot change it.

[2Bdecided]

If I found two independently recorded audio sources for the same event, I wouldn't expect them to be in sync.

I'm sorry, but that doesn't make any sense at all. Time is a constant, cameras cannot change it.

Setting aside Einstein for a moment, I think you'll find that all the clocks in your house won't stay in sync forever - and it's the same with recording devices (unless locked to a common clock).

Even if the two versions were derived from a common master, asynchronous sample rate converters are common, meaning that a 44.1kHz CD will not necessarily sync with a 48kHz DVD over the course of an hour. Sometimes even two "identical" CDs won't sync because someone chose to re-master the same content for another market via such a device (or by doing D>A>D!).

http://www.hydrogenaudio.org/forums/index.php?showtopic=14060&hl=dido&st=31

Cheers,
David.

[lordsmurf]

Yes, but the clock time won't matter -- the audible period of time should remain.

You are correct, and on to something, about the conversions. I've experienced that myself. That is on possible solution, but it is less common than a simple dropped frame scenario from whoever created his source video.