FFMpeg has a nice audio "filter" called "atempo".

This filter is already in other projects, such as Kdenlive and Shotcut.

What it does is, you can speed up audio, and will adjust the pitch so that the audio sounds more normal, but faster.

It does not sound like "Alvin and the Chipmunks" :)

This behavior can be seen when you watch a YT video, click the gear icon, and select a speed greater or less than 1.

I'm attaching the FFMpeg sample code that I had modified/played with years ago when I was learning it.

I 'tweaked' it today, so it will compile in Ubuntu 21.04 using a c++ compiler.  I used Qt.  There's depreciation warnings and this certainly isn't production code.  But it should help others to grasp the concepts to implement it.

My Qt pro file has this:

TEMPLATE = app

CONFIG += console c++11

CONFIG -= app_bundle

CONFIG -= qt

SOURCES += main.cpp

LIBS += -lavcodec -lavformat -lavutil -lswresample -lasound -lavfilter -lasound

I put an Option 1 and Option 2 in the main.cpp file.

Option 1 simple writes your infile - no modifications to out.raw.

Option 2 applies the atempo filter.

So comment and rebuild accordingly.  It should only take 2 seconds or so to compile.

I'm hoping, that perhaps someday, I can simply drop an effect onto my timeline so that I can

speed up video/audio in one go and have nicer sounding audio for my needs.

Thank you in advance for your consideration.