Newbie: How do I exchange the audio from one AVI to another?

[Joaquim]

Ok sorry if this is too much of a dumb question but...

Here's the deal.

I have two AVI files, of the same video.

One of the files has GREAT audio

The other one has really BAD audio

They have a slight variation regarding length, but the video is the same.

It's just that one of them has a little more "black video space" than the other juts before the very same video starts.

I would like to take the GOOD AUDIO from one of the AVI files and thrown it in the OTHER AVI file, which has awful audio quality.

I fear that, since the length of the videos vary slightly, this might cause problems (video out of sinc)

Can some illuminated soul help this poor ignorant video watcher?

Thank you A LOT in advance.

Making things short I have

FILE A.AVI (bad audio)
FILE B.AVI (same images, slightly different in length, GREAT AUDIO)

How can I throw the audio from FILE B to FILE A successfully, and put it in sinchronicity?

Thank you very much!

Joaquim

[Shadowmistress]

This is going to be a nightmare to try and resync. It's probably not worth attempting in the long run. But if you feel you must....

Use virtualdub to open the good audio file. Save the file as a wav. Then open the bad audio file. Select the wav file to use as the audio. Then go to video> select range> and set your time offsets until audio and video match. There's no way to "detect" what the proper setting is, you have to play it by ear. Then use direct stream copy for video and full processing for audio with compression selected, and either resave as avi or frameserve to an mpeg encoder.

IF the two avi's have the SAME framerate, what you could do is copy and paste the extra frames of black to the beginning of the shorter file so that the second has the same length. Theoretically, audio should sync itself after. To do this, find the first frame both files have in common and count backwards from there. Open the long clip, cut, then append avi.

Have fun. I don't envy you.

[Josef Kneht]

Joaquim,

You perhaps could perform this only if you'd have the same video
sequence. BU as far as I know they have different length. That means you will not able to change audio streams, at least simple.
But if you are video engineer I'm sure you can do this by any professional NLE program by set every audio sample with an appropriate time stamp

In other words forsake this idea

[manono]

Sorry shadowmistress. No reencoding of either the AVI or the audio should be necessary. It's not a nightmare, but will just take some time to do correctly.

1. DEMUX THE AUDIO FROM THE GOOD AUDIO AVI: Open the AVI in VDubMod, clicking no if it gives you the message about improper VBR. Go Streams->Stream List->Demux and give it a name with the proper extension.

2. ADD GOOD AUDIO TO AVI WITH BAD AUDIO: Open the AVI with bad audio in VDubMod. Go Streams->Stream List->Disable the bad audio. Hit Add and browse to the good audio and Add it. Right-Click on the new good audio and go to Interleaving. If it's MP3, leave Preload and Interleave alone. If it's AC3, then maybe set both for 96 .ms. Estimate the delay. That is, estimate how much the new audio is going to be off, based on the difference between the length of the 2 files. It doesn't have to be correct as we'll fix it soon. OK your way out of there. Set Video for Direct Stream Copy. Go File->Save As and give it a new name.

3. FIXING THE AUDIO SYNCH: Play the resulting AVI with good audio. Estimate how much it's out of synch and if the delay is positive or negative. 1000 ms=1 second. Open this AVI in Media Player Classic. Right-Click the screen and go Options->Audio Switcher->check Audio Time Shift. Again, estimate the delay and if the sound plays before or after the lips move, or the door slams, or the gun fires (sharp sounds are easier to figure on). If you hear the gunshot after the gun fires, then you want to apply a negative delay. If the sound of the gun happens before the gun fires, then you apply a positive delay. Set that, OK it and resume playback. Adjust until you get it right. MPC makes real time adjustments. Once you have it, write down that delay (with positive or negative), uncheck that box and close MPC. Close and reopen VDubMod (close so the previous delay isn't kept). Set Video for Direct Stream Copy again. Go Streams->Streams List->Right-Click the audio stream, set the nterleaving as before and apply your delay from MPC. OK your way out of there, go File->Save As, give it a new name, save and test.

All this assumes that the movie itself is exactly the same between the 2 files, same framerate and same number of frames.

[Shadowmistress]

Sorry shadowmistress. No reencoding of either the AVI or the audio should be necessary.

You're right. I've edited my instructions to change "full processing" to "direct stream copy".
Other than that, your steps 1 and 2 are exactly the same as my instructions. Your step 3 is unecessary since you can preview the audio delay in realtime right from virtualdub and don't need to bother with Media Player at all. (Just use the play button with the little 0 under it instead of the button with the little I under it.)

[manono]

And following your instructions, you've given him a WAV file as the new audio, thus ballooning the file size unnecessarily. If I inderstand the OP correctly, he's just replacing the audio in an AVI, with no further conversions. You're having him use VDub for the job, and it doesn't support VBR MP3, and using it is a recipe for audio asynch. VDubMod is a much better choice. Neither VDub nor VDubMod were designed to be players, and although maybe they'll work to help synch up the audio, I wouldn't trust them. None of that copy and pasting of black frames is necessary, just causes extra work, and there's a chance that he'll have keyframe issues anyway. No, although the job isn't a nightmare, you turned it into one.

[Shadowmistress]

Riiiiight, like trying to sync audio by ear isn't a nightmare in itself?

You're right about the wav file though. (Probably why my instinct was to choose full processing in the first place.) It actually should be direct stream copy for video and full processing for audio with compression selected. The downside is that you end up converting the audio (but which would cancel out any mp3 or vbr problems).

I've never used vdubmod so I can't speak on whether it's better or not. And I'm running WMP 9.0 on win98 and when I right click on the screen, no audio switcher option is available to me. So if I were the op, your advice would be useless to me.

I still say inserting the extra frames is the way to go. You'd get much more precise sync rather than by trying to play it by ear. At most you'd be 1 or 2 frames off due to GOP, but there's no way you'd get such sync accuracy by eyeing it.

Plus there's always a chance that interleaving by too much can confuse your settop player, depending on how much blank space there is on the other file.

To each his own. Now the op has 2 choices on how to do it depending on how much patience he has to try and sync it.