Concatenate and crossfade audio to form a very long sequence.

• Create virtualenv
• Install requirements
• Point uberfader at a directory of WAV files and tell it the desired output length, e.g. 600 seconds:
  python3 uberfader.py -i ./bits/ -o ./long.wav -l 600

• The underlying Pydub library exhibits quadratic behavior with long sequences. Instead of generating a very long sequence in a single run, you may have better luck generating a number of shorter ones first, then re-uberfading them. Use the -n parameter to have Uberfader generate N files (suffixed e.g. long_0001.wav) and then do python3 uberfader.py -i ./long_sequences -o ./really-long.wav -l 3600 to generate the final sequence. Your audience probably won't realize what's happening.