VLC can speed video or audio up/down on the fly, preserving audio pitch. I'm using it with audiobooks and old movies, and also occasionally (without pitch lock) to turn hard house into sweet groovy house or breakcore into playful idm, as suggested by RDJ himself—see https://youtube.com/watch?v=5yBvP3616Wc and https://youtube.com/watch?v=aWqf17mUyoQ
Btw, for some reason ffmpeg doesn't do well with changing speed of music—the result sounds poor compared to VLC. I found that `sox` gives better quality.
Ah, and I neglected to note that VLC does the speed-trick both on desktop and Android. On a phone, it's not quite perfect for audiobooks due to some hiccups in controls, but the versatility is its favor.
Lots of love to mpv in general because it's an awesome tool, but VLC also have hotkeys for those things + I'm pretty sure VLCs feature set is much larger than mpv while still being super lightweight.
Btw, for some reason ffmpeg doesn't do well with changing speed of music—the result sounds poor compared to VLC. I found that `sox` gives better quality.