Hello,
I cut a piano music video and when I change length and preserve pitch in different tracks, I get problems: I hear sometimes an echo and so on. What is the right crossfade to hear nothing else like the original piano music without any echo or other things?
you need to play around with the different available settings. it's possible that you might not be able to get a stretch without artifacts using the built-in stretching tool.
maybe try Acid's stretching capabilities or a 3rd party plug-in.
If it's a musical track, it'll be hard not to hear at least SOME artifacts. The settings that produce less echoing usually tend to make the music sound out-of-tune instead. There simply is no "wonder"-setting.
May I ask exactly what you're doing to that poor piano track? Wouldn't it be better to make the video fit the music instead? =)
I was after a very decent timestretch DX plugin a couple of months ago. After much digging, asking and searching, it seems such a plug doesn't really exist. What I was recommended, though, was Prosoniq Timefactory. It's a standalone program and isn't exactly cheap, but sounds incredible. The UI ain't great - can be fiddly - but the results are invariably fantastic. Reminded me of the timestretching on old DAR workstation DAWs.
If you can afford it, it's definitely worth getting.
Also, you may have an unrealistic idea of what can be achieved with time-sretching/pitch-shifting. Anything other than a small amount can sound *really* artificial with any algorithm .