Remove multiplication of sample rate for pydub indexing
When loading segments, specified with offset, files that are not supported by SoundFile (i.e. filetypes that are non-seekable such as GSM encoded wavs) the script resorts to using [pydub](https://github.com/jiaaro/pydub). 

Pydub uses millisecond indexing. Fix to remove incorrect multiplication with sampling rate at offset.