Audio & Video Synch Issues

I converted my original audio file from my video into wav format. It was the same length 44mins 37secs as the video part. I opened it up in audacity, I took away some dead silence, unwanted noise and replace it with audio. But the audio doesn’t match the video it is about 1 min longer than the video…there wont be the correct sound at the correct part in the video… I am not sure what to do, I spent a lot of time on it so far

When you got done editing, did the Length window under Audacity say 44:37? Did you Export as a brand new file or step on the old filename?

MP3 files are notorious for messing up length of a show—just a note.

A minute off is pretty serious. Does it start out life perfect and then gently drift off? Does it get to your edits and then suddenly not match?

Audacity will not edit video, so how are you combining your new, repaired sound file with the video? Did you set Audacity for 48000 16-bit Stereo? That’s how most video sound files work. Most video editors “know” about 44100, but if you’re having troubles, it’s good to eliminate all possibilities.


Compressed video formats can sometimes go out-of-sync when edited. So, the 1st thing to try is to extract the audio and then re-multiplex it with the video to see if it stays in-sync. You might want to do something “harmless” like reducing the volume so you can be sure you’re actually replacing the audio. If that goes out of sync you may have to re-encode the audio/video to a different format before editing, etc.

And of course, any time you’re editing the audio from a video, it’s important that you don’t do anything that can change the timing or length. i.e. You can mute certain sections and mix-in new parts over the muted parts, but don’t “cut-and-paste”.

Select the whole piece by clicking just above MUTE. Does the Length window on the bottom match what you’re expecting? That’s critical. If that doesn’t match, the new clip is never going to fit.


here are some more details.

In audacity it says to change my file to a compatible format. So I converted to WAV and opened up the sound in wav format with audacity
I wrote down all the time frames to the precise fraction of a second where there was any unwanted noise
I went on youtube and downloaded some free audio tracks, I also converted them into WAV format
I open up the sound file of the video
In a separate audacity window, I open up the audio track, just one a time.
Some areas where there was unwanted noise are small maybe 40 seconds some are over 2 mins with me not talking.
I would highlight any areas with unwanted sound and used the generate’s silence option to get rid of any sound in the selected area
So I would Subject the ENd time and start time to know exactly how much to replace.
For example 28mins 43.101s - 27mins 2.352s…1 min 40.749 seconds
So In the audio file from youtube , i would select 00h 00m 00.000s as a start time and 00h.01min.40.749s as a end time.
I did the only thing I really understood in the message/ no to do was cut and paste, So I would cut and paste the difference in the unwanted parts. so for example cut and paste 1min.40.749s of a free song youtube as under their create option into the sound version of the video.

After I got done I selected “save file as” and made it into a AUP file, then I exported the audio…Should I just export the audio?

I noticed there is a thumbnail option “silence audio”, is that the same as the “generate- silence” ? Until i hear from some I will try my luck with it

I am going to have to restart over, I was opening up everything in separate things, I am going to try the import option to keep everything in one location, im going to try comparing two originals and see if i can figured it out that way.

So I hope someone can give me a really good idea how to synch everything right when adding music. I can try adding music clip in the video editing software but I am getting really use to audacity so I will try a few more things in audacity first

Audacity will tell you what you have. You don’t have to export and match to see what happened. Click just above MUTE on the finished track and the whole track should select.

There is a time window underneath the timelines that can switch between END and LENGTH. Select LENGTH. Is the show the right length? That is a convenient, on the fly method to make sure you’re not changing the duration match by accident.

You can drag-select a portion of the timeline and silence it with Control-L. The timeline should get flat.This will not change the length of the show. What you can do then is Import, for example, a music clip. It will appear on its own timeline underneath the show. Use the Time Shift Tool (two sideways black arrows) to push the music into the right place and the various fade and amplify tools to make it match. Audacity will play all tracks at once unless you stop it with the MUTE and SOLO tools.

Keep stacking up tracks like that until you get all the pieces you need for the completed show.

Save a Project and Audacity will create an AUP file and a _DATA folder

which will recreate the whole stack of music, comments, voices, etc, etc. Terrifically handy if you want to go back later and, for example, change the music. Projects do not save UNDO!!

Projects only open in Audacity.

Exporting a file will produce a perfect quality WAV sound file (Audacity default) with all your different timelines smashed together into one mixed show. This will open anywhere on all three computer types, but you can’t take the show apart again and change one thing. You’re stuck. WAVs make good archives. I have many client recordings backed up as WAV.

And later, way down at the bottom after you finish everything else, you can Export an MP3 file for posting or transmission to a client or on-line service…or a personal music player.

Once you make an MP3, that’s the end of the world for editing. Every time you edit an MP3, the distortion gets worse and the quality goes down. You can only successfully edit the WAV or the Project.

There is a very New User mistake that’s particularly evil. DO NOT step on old filenames. When you make a WAV, make a WAV whose name is different from everything else. If you back up your work, make those backups to different names. If you use dates, use ISO dates such as 2016-09-25. Slashmarks don’t travel well between computers.

You should be able to go back to the original voice recordings and make a new show if something happens, you’re unhappy or the client wants a different version. If you kept saving new work and corrections on top of old work, the first time the computer does something wrong all the versions turn to dust and you have to go all the way back to the beginning and announce the work again.


I was in the middle of re writing everything I did but saw my post got approved. Okay so I am basically going to re do everything over , maybe cutting/pasting or copying/pasting after muting the file. Someone mentioned mp3 can mess it up…I think that might be the issue. I just remembered i never converted the music audio file into wav format. however my next post will be a very very detail list of what i end up doing. A lot of you have been suggesting extract the audio and then re-multiplex…as my name suggests i am pretty new to all of this so I have no idea how to extract the audio and then re-multiplex. I started working with audacity since I wanted to improve my gaming streams with a video editing software. I started using hitfilm 4 express so I mean once i fix this audio thing, it will be the original video but custom sound in my video, I could try it with hitfilm 4 express but I think i mentioned this before…I am getting use to audacity so i want to exhaust all options with audacity.

See …

Don’t do anything to the audio in Audacity which alters its duration, as that will knock everything out-of-sync.