The golden mantra: "FCP does that".
Try importing the project in a new project, then exporting your video again.
Quicktime's container header is incredibly flexible and there's maths in there and very often (especially with FPS other than 29.97) FCP gets things wrong in that area, then Quicktime has to guess.
If you're brave enough to see the guts of the ...
fight club's mid air collision is one of the best.
castaway - also epic
dark nights Bane plane heist scene was the best scene of the whole film. (no youtube there, sorry)
The important thing to realise is that time-stretching audio works in a fundamentally different way from video slow-motion. For video, it's really simple: you just record at a higher frame-rate and slow that down to something more usual.
If you apply the same technique to ordinary audio, what you get is not just slower, it is in particular also lower in ...
The audio equivalent would be the sample rate which is the number of times per second a discrete sample is taken. The higher the sample rate, the more time-resolute the result.
To sort-of answer your second question, the higher the sample rate the more likely that a time-stretched signal would resemble an original at the stretched rate.
If you didn't use a clapper when you filmed, then you need to find something in the filmed portion where you can see something happen that causes a percussive sound that was recorded. A drummer hitting a drum that is caught on video and audio is one example.
Then it depends on your software and exactly how you filmed and recorded. If the video and audio run ...
Altering the speed from 24/25 FPS would mean speeding it up by 4.16666%.
By Pitching up the sound by 70 cents you will speed the video up by 4.1250%
or by pitching it up by 71 cents you will go to 4.1854%
In both cases the new file will not have an absolutely correct length, but if the total length of the video is not more than 20 minutes it should be ok.
I haven't seen this film but after watching a short screening of this scene at film school, I kind of want to. I like this scene because watching and listening to it made me feel really uncomfortable, it's just the way I imagine when I'm on a plane, I feel very paranoid thanks to doco's like Aircrash Investigation haha. The one in Cast Away is quite cool as ...