How to Fix Gradual Audio Desyncing in Your Video in 3 Steps

By Taisan

To play along, you will need 3 things:

- A movie, hopefully one that's desyncing in the audio department
- VirtualDub
- A sound program that will force a resample rate on a wave file - My choice? I use Sony's Sound Forge 9 in this guide.

All set? Let's begin.

Step 1: Extracting the audio

Open up VirtualDub and drag your movie into the window to open it up. Now go to File > Save WAV



Name and save that file anyway you want, just don't forget the little fella.



While you're in VirtualDub, slide the slider all the way to the end of the movie, and make a note of the length, right down to the millisecond.



Alright, we got an audio file, now let's tweak it a bit.


Step 2: Fixing the audio

Open up your sound editor program (Sound Forge) and drag your freshly created wave into it. What the hell?! Check out the length of the audio!



The audio doesn't match the length of the video! (If your audio file has a dead air buffer before and/or after, you can highlight the length you want and you can see it in the green square that I kindly drew in)

Time for a little stretch, Mr. Audio File! For Sound Forgers, go to Process > Resample



First, make sure that Set Resample Rate Only is checked. Don't worry about anything else. Now, this is the part where you must do a little experimentation. Here's the golden rule of desyncing:

If the audio is shorter than the video, set the sample rate to a lower number to make the audio longer. (Do the opposite if the audio needs to be a shorter length.)



In my case, I need to lengthen the audio, so I set it to a lower bitrate and press OK.



Well how about that, a good number on my first try! Now the length of the audio is much closer to the length of the video. It doesn't have to be perfect, but the closer the better. If the result isn't what you want, no problem: just undo and set a different resample rate. Once you got something you're happy with, set the wave file to a resample rate that won't make any editing software complain. Go to Process > Resample again, but this time, uncheck Set The Sample Rate only. Don't worry about filters or any of that crap, the change will be slight and unnoticeable. Change it to 48000 and hit OK.



It'll process for a bit, but when it's done, you'll have the proper length of the audio set at a workable sample rate! Rock on! Of course, don't forget to save your hard work. I like to use a filename with the sample I set it to for reference:



Congratulations, you got a fixed audio file! But don't bust out the Fanta yet, we have one more step to do:


Step 3: Put the audio back into the video

Open up VirtualDub and load the movie back on. This time, go to Audio > WAV Audio...



And choose the file you just made:



Now your video will play with the fixed audio! Give it a listen in different parts and see if everything is alright. If the audio is consistantly off as opposed to a gradual desync, go to Audio > Interleaving



And use the Audio Skew Correction to make adjustments. The program is self explanatory with this feature, no need to repeat how it works.



Play around with the values in the Interleaving and see if you get any good results. If things still don't seem right, you can always make another file in Step 2 and try again. But, if you feel the video is ready for our LP viewing standards (and it better, otherwise put it on YouTube, oh snap!), let's save the video. Go to Video > Put a dot next to "Direct Stream Copy". This will make the program use the codec the video has. Leaving it on Full Processing will make giant files of doom.



FINALLY!!! This is the last step. Go to File > Save as AVI..., choose a spot...



Wait for processing, more processing, blah blah blah. When it's all finished...


You got a properly synced video, buddy. Congratulations! Now I never want to watch another horribly desynced video again



Another method!

I recently stumbled across a method of audio desyncing which makes the desyncing process so much easier. Keep in mind, this will only work if the video and audio were recorded at the same time. That probably covers 98% of the videos made for an LP. Check it out:


Run VirtualDub and open up the video. Go to Video > Frame Rate:



Now place a dot next to Change so video and audio durations match and hit OK:



Go to Video > Put a dot next to "Direct Stream Copy", then save it by going to File > Save as AVI... Ding! It's finished, that's it! I tested this with a 3 minute and a 15 minute video, and I was pleasantly pleased with the results. Give it a try, you've only got a few short clicks to lose! Now, we return to your regularly scheduled tutorial: