How to change the audio pich when playing back video?

Question

I'm developing a video player for playing karaoke videos. One useful feature would be to change the key of a song while playing back. So how could I modify the audio stream of a video while playing back in a QT application? There seemed to be hardly any information about this.

Answer 1

Audio signal processing is quite complex and I expect fairly mathematical. The question has previously been asked here on StackOverflow , so if you're going to want to do the actual processing yourself, reading that thread and following the links will be a good place to start.

If you're new to audio signal processing, you may be better searching for a library that does what you want, to include in your project.

Answer 2

There are many ways to achieve a Pitch Shift effect that you are looking for. I know You are working with c++ for your project but i think this tutorial for a Max MSP patch will help you understand some of the basics of one Pitch Shift algorithm. I don't know how familiar you are with digital audio theory but a few things you will need to look into are FFT , and Generating sine waves in code. I personally still do not have a mathematical grasp on FFT works but if you know what it does it can help you understand how to deconsruct audio signals.

Good Luck, Happy Coding