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-   -   Ensuring AUDIO is in Synch (http://www.dvinfo.net/forum/all-things-audio/145641-ensuring-audio-synch.html)

Mike Hardy March 11th, 2009 08:32 PM

Ensuring AUDIO is in Synch
Boy, are you all going to laugh at this one. I have quite a lot of experience NLE editing, but in the past I have simply applied backing music to the footage, having never needed audio dialogue.

Alas, I now have to do a couple of filmed interviews, where the foootage of the interviewee, will be interspersed with cut aways to subjects about which they are speaking. Now, never having done this kind of thing before, (although I'm more than confident in garnering the audio itself), I'm concerned that I'm not sure of the best way to maintain absolute synched audio. To my mind, if I am going to cut and edit the interview, I am obviously going to insert additional actuality or other footage, whilst the interviewees voice continues.

My problem is; when I do cut back to the interviewee, how do I ensure that their voice is still in perfect synch with their mouth? Presumably, I am going to have to create some kind of seperate AUDIO file, to insert into the NLE timeline?

When you guys have finished the mirth, I'd love some advice!!

Chris Rackauckas March 12th, 2009 01:34 AM

Can't you snap the audio to the video? I'm pretty sure you can link them in Vegas. Link the audio and the correct video to move in unison, and then when you move the clips of whoever's being interviewed, the audio that goes with it will be moved too. I'd assume other NLEs can do this.

Rick Reineke March 12th, 2009 11:19 AM

With an audio NLE, my MO is to keep the video editors rough audio mix on a separate track grouped with the reference video and both locked to the time-line so they cannot be moved. Then I import the OMF file tracks and work from them. This way if something looks outta sync with the reference video, I can verify it against the rough mix. (known sync)

Jay Massengill March 12th, 2009 11:53 AM

Which NLE will you be working in?
In Vegas, the link between a video segment and its matched audio from capturing the footage is automatic when you place it on the timeline. You'd have to purposely (or accidently) break the link in order to create an out of sync situation. Just adding cutaways or actualities over the interview video won't create an out of sync condition.
If you do create an out of sync situation, Vegas is pretty good about visually indicating that condition. If you slip something out of sync, the region turns pink and you'll see that on the timeline right away.
The "Ignore Event Grouping" icon allows you to slip or trim audio separately from the video footage. This is a useful but dangerous command and has to be used carefully when needed and kept inactive for normal editing. For what you're asking, you don't even need to use this command.
If you're adding cutaways or actualities over the interview footage, you simply put those on a video track above the interview video track. Regions in the higher video track dominate any time they occur, so you don't have to make any additional change to the interview video or audio. You can mute the actuality audio or play it at a greatly reduced level to give some natural sound under the interview vocal.
In other words, in Vegas at least, the lower video track containing the interview footage and its matched audio are still happily cruising along in sync while Vegas automatically switches the output to show the video regions on higher tracks as they occur. You aren't required to cut the interview video and audio separately from one another, so there shouldn't be a cause for an out of sync situation.

Bernie Beaudry March 12th, 2009 01:00 PM

A good way to check sync visually is to look for hard consonants in the dialogue track such as t's or p's. Watch the person's mouth and if those types of sounds match up with the mouth you're good. Of course this doesn't assure absolute sync but its a good quick way to notice problems.

Mike Hardy March 12th, 2009 06:11 PM

Thank you so much for your comments. I will be using Videostudio 11+. I also believe I am going to have to make a SEPERATE audio file, so that the speech from the interview can be 'layered' over other footage as obviously, when you edit the actual video of the PERSON being interviewed, the audio is also edited and cut/removed when cutting to other scenes.

Chris Rackauckas March 12th, 2009 07:27 PM

Well, just set all of the audio sources to where they sync, and lock them all to the video. Once they are all locked, just cut in the other video clips as necessary, move everything else around, and then use mute automation to chose which feed of the audio to use.

By locking it before you move everything, all of those audio files that you synced up will still be synced when doing this. That should make it pretty easy.

Jay Massengill March 13th, 2009 12:35 AM

Can you buy a new video editing software package? Consumer versions of Vegas Movie Studio aren't very expensive and have huge flexibility advantages over products like Ulead Video Studio 11+.
For one thing, you won't have to go through what you're describing where the limitation of how tracks are used in the software requires you to cut, space and then relink audio and its matching video.
In Vegas (even the consumer version that's limited to 4 fully functional video and 4 totally flexible stereo audio tracks) you wouldn't usually have to do that in normal editing. You wouldn't have to "cut into" your interview footage, you simply layer the cutaways and actualities on a higher video track and Vegas handles it automatically. Perhaps your software can do this too and it needs more investigating. Many, many years ago when I tried similar products, the type of track and how it could be (or couldn't be) manipulated was a big limitation and created situations like you're describing.
Think of it using this analogy: We've all watched live television. When they cut from Camera 1 to Camera 2 the viewer then sees only Camera 2 but Camera 1 is still producing a continuous image that's streaming along behind the scenes. The stream from Camera 1 doesn't get chopped off, it's just not visible to the viewer until it is again chosen to be the main source. It's still in sync with everything else because it never stopped running in the background.
Editing with a fully flexible multi-track editor like Vegas is the same. The base layer of matched video and audio (your interview footage) doesn't need to be chopped up to make room for other video cutaways and their matching audio. Vegas acts like the technical director during live TV, switching to the footage that's placed on multiple tracks in the timeline without literally chopping off the other segments. Sections of footage that aren't being seen at that moment (because they are on a lower video track than the currently visible segment) are still running along staying in sync until they again become the dominant visible source. That occurs automatically when there is no other video footage running on a higher video track.
You've been working under the analogy of assembling pieces of film or using a single-track NLE, where footage literally had to be cut into sections to "make room" for the next visible images, therefore disconnecting the relationship between some segments of the matching audio. If your software has limitations on how tracks are used and manipluated, thus creating a limited amount of room to work in, then it doesn't matter how many tracks it says you can use. They won't give you full flexibility to layer video and matching audio without running into snags like you've described.

Ken Campbell March 13th, 2009 02:30 AM

+1 for any version of Vegas, although the Pro version packs a lot of advanced punch. I have been editing music videos lately and regularly shoot up to 20 takes which get sliced and diced and then sync'ed to a master track. Couldn't be any easier with Vegas.

Note that Vegas was born as a DAW software (digital audio workstation) and quickly morphed into a NLE. That heritage makes working with audio a breeze.

Steve House March 13th, 2009 04:34 AM


Originally Posted by Mike Hardy (Post 1026819)
Thank you so much for your comments. I will be using Videostudio 11+. I also believe I am going to have to make a SEPERATE audio file, so that the speech from the interview can be 'layered' over other footage as obviously, when you edit the actual video of the PERSON being interviewed, the audio is also edited and cut/removed when cutting to other scenes.

Not familiar with that NLE but when you drop a clip containing audio and video such as an interview would have onto the timeline, do you not get two tracks, one for the video and the other for the audio? If not, perhaps it's time to investigate your upgrade options because the capability to edit audio and video separately is a fundamental requirement for any serious work.

Gareth Watkins March 13th, 2009 05:17 AM

Hi Mike
Software issues aside, I imagine techniques are more important for your editing than the NLE you use. Most NLE's should allow you to knock out a standard interview.

Assuming you only have one camera to shoot with, two is a luxury that makes editing easier...but provides more sync issues.

I always set up a lock down head shot and film the interview in one take on the subject... This is then easy to edit as image and audio are always in sync. Your interviewees voice is always on the one track.

You can use L cuts to add your cut aways, noddies, etc...These also help mask jumps in the images when you do need to make a cut, as well as illustrating the subject being discussed...

I try to make a note of all the things discussed so I can go and get as many cutaways as possible after the end of the interview... (the more the merrier)

Once I have the interview in the bag, I then set up a rear shot over the interviewees shoulder to get the interviewer... I then run through the questions again...
These questions I can cut into the interview time line... (An experienced interviewer will know not to speak at the same time as the interviewee, to let him finish his sentances at a natural pause, otherwise it makes editing far harder and more limited..)

With this technique you can overlap the audio at the start of an answer or a question so you get the interviewee/interviewer listening. It then runs into the answer seamlessly...

Ok it is a lot of faffing about to get it all but with practice it edits together to make a good piece of video...

I enjoy doing interviews as with thought you can build the clip in your head as you shoot...

Hope this helps

Ken Campbell March 13th, 2009 12:02 PM

Hi Mike, I think I understand what you are asking. You could lay out the whole interview on one video track with its associated audio track that is locked in sync to it. Then put all overlays on tracks above and delete their audio tracks, or mute them. Many programs have the ability to add only the video track to the timeline as well.

Mike Hardy March 14th, 2009 12:17 PM


Originally Posted by Ken Campbell (Post 1027148)
Hi Mike, I think I understand what you are asking. You could lay out the whole interview on one video track with its associated audio track that is locked in sync to it. Then put all overlays on tracks above and delete their audio tracks, or mute them. Many programs have the ability to add only the video track to the timeline as well.

Hi Ken and thank you for your response, (and very many thanks to everyone else who is helping also). You are quite correct. The problem I have is, I want to integrate footage into an interview, which I have filmed, and which naturally contains the video and audio locked into the timeline of my NLE. The problem is, that when I insert footage, say relating to the topic the interviewee is talking about, it naturally 'cuts off' the spoken audio because I have effectively 'cut off' the video of the interviewee speaking. So I am sure that I am going to have to SEPERATE the audio from the video, in other words create a seperate AUDIO file containing the spoken words, which I can then have running through the AUDIO section of the timeline. My problem is that I have to ensure that it keeps in synch. I'm probably not being very clear, so I shall give an example:-

Subject is talking about diving in the RED SEA. Show footage of interviewee talking enthusiastically. CUT TO underwater scene of Angel fish on Marsa Alam, about which she is talking. NOW, I want her voice to remain on the UNDERWATER FOOTAGE that I am showing, and when I cut BACK to her, I want the audio to be still in perfect synch. If I dont make a seperate audio file, when I cut to the footage of the underwater scenes, I naturally cut off the interviewee speaking. Is this making sense?? Furthermore, I would probably want to keep the ambient audio relating to the underwtare scenes also, either music and/or bubbles and sounds of diver exhaling.

Boy, I know how to use a camera but I know diddly SQUAT when it comes to audio!!!!

Jay Massengill March 14th, 2009 03:15 PM

The situation you describe where the main audio is being cut-off would only happen if your software is extremely limited, or you're using your editing software incorrectly. All but the very simplest editing programs allow you to place a video cutaway on another track without disrupting the audio from the main video-audio track.

You should place the cutaway footage on a different track, not cut it directly into your main footage track. That message has been repeated by almost every responder and is key to what you want to accomplish easily for most software.

The only reason that wouldn't work is if your software doesn't allow more than one track of linked video-audio at a time, even though it allows additional tracks of video overlay (like graphics or text) or additional tracks of audio (music or narration) but can't have two separate sets of linked video-audio running at the same time. If that's the case, then you need new software or you'll have to use "L" cuts or "J" cuts. That's more work, less flexible, and it doesn't easily allow low-level audio to accompany your cutaway footage without going to additional steps. It's an out-dated way of working and should only be used if you have no choice and are limited to one main video/audio track by your software.

(It's also possible your software is set to always chop in extra space in the footage that's already been placed on the timeline to allow for new footage placed at the point you want the cutaway to start. That would disrupt the audio of the main track, but that's either having the software settings incorrect or it's a limitation of the software that can't be turned off. Look for info on "Ripple" in your software help. You would want ripple to be "off" when you're adding cutaways.)

Have you explored the tutorials that came with your software? The editing task you want to accomplish is one of the most common uses for NLE software and should be described in a tutorial.

Ken Campbell March 15th, 2009 05:41 AM

Hi Mike, it seems to me that your NLE software is your limiting factor then, in which you can't efficiently manage tracks. I am not familiar with Ulead's stuff. I am familiar with Vegas and somewhat with Premiere and there would be no problem with either one. Unfortunately, you may have to think about investing into another NLE.

I can recommend any version of Sony Vegas, and the lower priced ones are remarkably feature rich. There is also a 35% off sale at the moment which means you could get a great NLE for less than what is normally spent in one night at the local pub.

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