Beat Time plays audio & video and can change the tempo (time stretch) and/or pitch and does note & chord detection. It is aimed as a practice / study tool for musicians and as a helper tool for transcribing audio & video. Play audio & video from your iPod library, dropbox, YouTube, iTunes file sharing or open from other apps.

Reviews:
"Beat Time! is a gem of an app that's just waiting for musicians around the world to discover it. It's almost to good to be true! You've got to check it out!!"
Jordan Rudess
Dream Theater/Wizdom Music.
"I've used plenty of slow downer type apps, and this is among the best! It does what it says and does it well" Evp73
"It's amazing how you can hear virtually NO artefacts in the audio! Amazing!" jenius92000

Main app features:
• Time stretch video and audio from 1/4x to 2x without affecting pitch.
• Pitch shift audio and video up to an octave up or down.
• Natural pitch shifting, pitch shift a male voice keeping it sounding male, pitch shift a female voice keep it sounding female.
• High quality, state of the art, time stretching / pitch shifting using DIRAC technology.
• Pitch analysis for note & chord detection.
• Annotate the track with multiple markers.
• Seamless looping of segments in the track.
• Optionally pause between loops.
• Easy file transfer: Open audio/video files from any app that supports iOS "Open In..." menu or using iTunes file sharing.
• Play YouTube videos.
• Built in dropbox integration.
• Open tracks from your iPod audio, video library or video camera roll
• Export time stretched / pitch shifted audio or movies.
• Universal application (iPhone/iPod/iPad).
• Supports video and audio formats that are playable using iOS music/video player, including: mp4, m4v, m4a, mp3, WAV, mov, (AVI provided it's mpeg 4 encoded)

See Jordan Rudess playing with Beat Time! at http://bit.ly/GO67NQ