how can I change the tempo/bpm of a song?

I use AUDACITY.
Open up the beat on the first track.
Import Audio (acapella) onto the 2nd track
Highlight the 2nd track and select Change BPM.
Then it’s a case of hit-or-miss until you get the right match.

If anyone knows of a better method then let me know. I keep things old school!

thats a difficult task I would like to see that accomplished.

You can easily do it with every basic sound engineering programm. As mentioned above ; Audacity, Virtual DJ …

Ableton Live 8 has a really nice time warp feature, you should try Live 8
[url:2zsieff9]http://www.ableton.com/downloads[/url:2zsieff9]

http://www.youtube.com/watch?v=waLeq8-2UBo

(btw, I’m not affiliated with Ableton, I just like using Live )

so in ,ogic is it really just that easy or is there a more technical approach to it aswell?

I have 5 years experience doing mashups. Ableton Live is the ONLY way to go. See the video above. Its a little tricky at first but once you ge the technique its very fast and the most professional application.

Also use "Mixed In Key" to find the BPM and keys of tracks.

[quote quote="skiingisfun":1vqwmy2i]I have some mp3 instrumentals and acapellas and I want to mix them together. However, the instrumental is 138 bpm and the acapella is 134 bpm.

How can I speed up the 134 bpm song to 138 bpm? Preferably I’d like to do it without changing the pitch.

Can this be done with Garage Band? What about with FL Studio?

I’m willing to buy additional software if I have to.[/quote:1vqwmy2i]

In FL studio, you will be able to drag both files onto different Track #’s in the playlist to edit and work with. In the playlist, click the bubble in the top left that say stretch so that it has a white dot in it. Go to the vocals file in the playlist and drag it to whatever length you like.

After doing the length and having each file (instrumental and vocals) on different "tracks", go on to put each file in a different ‘channel’. You do this by going to the step sequencer, which should now have each file’s name listed on the left side and whatever other samplers you have on there, most likely Kick, Clap, Hat, and Snare. Click on the box that the "vocals” file name is in and another box, the channel settings, will pop up for that "sampler", but in your case, it’ll be the vocals. In the channel settings box you can change a ton of settings for whatever sampler/file is on that channel, including pitch (With the knob labeled "PITCH" at the top in the middle.) Change pitch that way until it is however you want it.

You can test bpm by using a "tapper" or other tool online.
Peace.

Awesome, have learned a lot. Thanks for sharing,

Have seen quite a few videos on how to do that in Youtube

In logic use the time and pitch machine.