Originally posted by: maurice2029
Originally posted by: Doctor M up:
Just 1 question; what is pitchshifting and what's the difference between pitchshifting and sped up? I don't know how I can see if the audo is sped up or not.

When something is sped up, you reduce the playing time of something and raise the pitch, because when you shorten the play time of an audio recording, the vibrations that make up sound are compressed together, so there are more vibrations per second, thus the pitch is raised. You can fix this in a sped up recording by pitchshifting, which is where you take the faster recording and artificially reduce the number of vibrations, thus bringing the tone down, while maintaining the faster speed.

So when American movies are converted to PAL, they run the films at a faster rate (roughly 4%) in order to bring the framerate up to 25 fps, and so they have to speed up the audio in order to bring it keep it in sync with the movie. Sometimes they just speed it up, making the voices sound slightly higher pitched than normal, and sometimes they adjust the pitch, bring it back down to the pitch of the original audio.

So:

sped up = faster & higher
toneshifting = time remains the same, pitch changes