Disclaimer: this is not a fully functional program. It is something i wrote in an afternoon. It has many flaws.

Essentially a little python script that you give three things: a spotify playlist, a target bpm (beats per minute), and an output folder to write to. It'll download the spotify songs for you and speed them up or slow them down so that they match the bpm you provided. This could be useful in conjunction with https://sortyourmusic.playlistmachinery.com/ to make running playlists. Make a playlist in the 160-180 bpm range and then use this program to get a nice smooooth bpm all along your run and not stuff up your rhythm every time the tempo changes.

This program has a couple dependencies that you'll have to install manually to get the program to work.

Here's a step by step:

1. Clone the repository

2. Go into the repository directory and run pip install -r requirements.txt

   I recommend using a virtual environment to install the dependencies and run the program (I've had some problems with it before)

3. install ffmpeg, if you have homebrew, just brew install ffmpeg otherwise you can download it here

And you should be done.

The program essentially just uses a bunch of third party python libraries to automate the process of downloading and conversion. It uses spotdl to download the playlist you provide and then calls the spotify API to find out the bpm of each song (it uses spotipy to do this, however i had to modify it as it hasn't been maintained for a while and there are some missing endpoints - which is why there's a copy of the source in this repo. The repository can be found here). Once the songs are downloaded, it uses rubberband (that executable you see in the root folder that I've added for convenience) to do the time-stretching and pitch-changing of the audio files. Finally, it uses ffmpeg to convert everything back to .mp3 format and bob's your uncle.

Feel free to copy this code, modify it, or contribute to your hearts desire. Like I've said, it's a little rough around the edges so it could use some polishing.

Downloading copyright songs is illegal. This tool is for educational purposes only.