Interpreting --stderr-progress

I'm trying to write a perl wrapper for cdparanoia but I am not 100% on 
how to interpret the output from --stderr-progress.  I've looked at 
main.c for help, but I'm still somewhat at a loss.

Can someone direct me to an explanation on how to interpret the text 
and/or numeric codes returned in the "##: %d [%s] @ %ld" formatted 
output?  Possibly equating them to 'smilies' or progress-bar symbols?
I can figure some of it out, but I'd like to eliminate the guesswork.

Thanks...

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Angus McLeod