I am in the process of building an app that records a user's voice and then apply a sound effect to it, like different pitch ( but with same tempo ), distortion, robotic voice, etc... Obviously there are a lot of apps doing this so it is possible. I saw a tutorial on changing the rate which in turns changes the pitch, but that's not enough ( and it also changes the playback length anyway ). I know the best way to go is to dive into the NDK directly, but this won't be an option in my case. I looked at third party libraries like LittleEndian but the cost is much too high.
Is there some way to achieve my goal, for example using AudioTrack ( with which I know sound effects can be applied ). I looked around a fair bit and some people are asking fairly similar question for this to be done on Android, but I am yet to find an answer.
If no one has done it in Android, are there resources on audio manipulation I could use to create each sound filter myself?