What is *.abk / *.ast from Need for Speed: Underground and are there programs that can convert file formats to WAVs? I tried Foobar2000 and vgmstream but it failed to load.

Samples:

https://drive.google.com/file/d/1wjEBkmkMs7lA78w5rIQmoVpk24rf9yr1/view?usp=sharing

https://drive.google.com/file/d/1vYoDVfkpIusqYubP9E50npSWJbNWIRlG/view?usp=sharing

I can load your ABK samples without any issues in foobar2000 with vgmstream plugin. Try update your plugin if you have issues loading on your side.

As for AST files, you can change extension to ASF and then you will be able to load music in Media Player Classic.

Can someone help me mod STRM_Music_UG0_MB.ast to add custom songs to Need for Speed Underground from MP3s?