Should you need it, you can convert .mp3 music to Sony PlayStation movies (.str) with multimedia converts like SUPER, that supposedly supports both formats. The result will be a blank movie with audio only.
Other than that, in past you could also find special utilities for avi to str conversion, but most of the links are dead. With them you could also manage some conversions, provided you first convert .mp3 audio to .avi.Open MP3 file Open STR file
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