Align two audio tracks in sync

[dexter30]

I´m trying to replace the original audio from an .avi movie (23.976 FPS) with the audio (another language) of the same movie that someone else recorded from TV (29.970 FPS ?) The idea is to have the original .avi perfectly in sync with the recorded audio.

BTW both audio tracks have the same lenght and there are no commercial breaks in the one recorded from TV.

I don´t know any info on this recorded video cause I have only the audio mp3, I don´t know how it was ripped, encoded, etc.

Problem is I try to align both audios in sync, but almost always end up having to make small adjusts throughout the whole movie, cutting, shrinking, moving parts of the second audio here and there, back and forth, to keep it aligned to the original one.

I have done this process several times with different movies and, strange, sometimes I only have to align the beginning of each audio track and they keep in sync up to the end!

Is there something I am doing wrong, what am I missing?

Any help will be much apprecciated.

[Sartori]

I did this for a music concert , using the mp3s of each individual tracks . I did it by opening both of them and adjusting every 5 or so minutes by stretching or compressing them , so that after each stretch the end of the new 5 minutes I had just processed alinged perfectly then went to the next five minutes - then cut or added silence to make the start of the next five minutes align , then stretched again (only selecting that 5minutes to stretch of course not the whole file) to make the end of it align .
Its a pain in the arse fiddly job doing that , but it looks like you have non linear adjustments to make .

[dexter30]

But it shouldn´t be a pain, that´s the point. Like I said before, there are movies I only have to match the beginning of the two audio tracks and the rest to the end is aligned perfectly.

[Sartori]

My point is in the final sentence , if they are not aligning then that particular soundtrack is non linear ie bits of it are stretched differently . Youre right , it shouldnt be a pain in the arse , preferably you can just delete a bit or add silence and it will align perefectly and sometimes when its a linear stretch , one adjustment and it works fine but some ways of mp3 encoding Ive found can stretch/shrink soundtracks/music in a non linear way (notably VBR) .

[hech54]

It's simple. The one taken from television has the edited-out commercials done incorrectly. Either too much of the dead space between the commercials and the show was removed....or vise versa. There is nothing you can do about it. Just because the lengths are the same means nothing.

[filmboss80]

Film prints can differ. In the TV version, perhaps a scene was shortened or extended. (Blade Runner is a good example.) Telecine speeds (especially with PAL and NTSC differences) can vary. TV networks can employ time compression or expansion to make a film fit a certain time slot. So you see, there can be a lot of factors to deal with.

There is no painless way to correct it, but it can be done. When overall speeds vary, I have used the Change Tempo (without changing pitch) tool in Audacity, honing down the settings until the waveforms matched. When speeds are generally the same, but shift at various points, I have used timeline editors (like Premiere) to synchronize sound tracks, adding or removing space here and there to keep the audio waveforms aligned. Sometimes, I have employed a little bit of both techniques on the same project to get the job done.

To do something right, you often have to roll up your sleeves and get busy.

However, if there is a DVD version of the movie already in the language you desire, it would be wiser to spend a few bucks for it. Time is money.