How to sync 29fps audio to 25fps video?

[asano]

I've searched these forums and tried a few of the options but the solutions are many years old, very contradictory (or just plain too techy for me to understand).

Can anyone tell me a simple way to convert/sync 29fps audio to 25fps video?

[hech54]

NTSC vs PAL?
It's "techy" because it's not as easy as it sounds and it requires work.....mainly changing the playback rate of the new audio.
I use Reaper (talk about "techy") to change audio playback rates.

[jagabo]

If it's a simple case of PAL speed up -- speed up the audio from you9 29.97 fps video by a factor of 25*1001/24000 (~1.04271). But be aware that releases of movies in different countries are often different cuts. In which case you'll have to cut/paste the audio too.

[asano]

^^ I've tried something like that before with Audacity but it seems to be guesswork as to how much to speed up or slow down the audio. I understand about different cuts for different countries, that's not a problem here.

Surely "changing the playback rate of the audio" can't be that difficult? I'm just looking for an easy to use app or even a guide on how to do it with a more complicated app would be nice.

[smrpix]

Audacity is about as easy as it gets, and jagabo has already done the math for you (~1.04271)%. Use the "change tempo" effect.

[jagabo]

If that doesn't work then there is an issue other than the normal PAL speedup. Assuming there are no cuts or additions you can find a sound near the start of the video and a sound near the end of the video and scale accordingly. Keep in mine there may be an initial delay or advance that you have to account for.

[asano]

Oh is it tempo I'm supposed to use in Audacity? I've been using change speed, whoops! I'll have another go...

[hech54]

I use Reaper because I can put both the original audio AND the new audio in there and adjust the new one accordingly until they match perfectly. I use the old free version of Reaper. No guessing.

[jagabo]

I use Reaper because I can put both the original audio AND the new audio in there and adjust the new one accordingly until they match perfectly.

You can load both tracks and edit visually in Audacity too.

Oh is it tempo I'm supposed to use in Audacity? I've been using change speed, whoops! I'll have another go...

They both change the length of the audio. The former keeps the pitch, the other not.

[hech54]

I use Reaper because I can put both the original audio AND the new audio in there and adjust the new one accordingly until they match perfectly.

You can load both tracks and edit visually in Audacity too.

Hmm....I'll have to try that.