This project provides bindings to the mpg123 library for Chez Scheme. It is currently a work in progress.

• [X] Library and handle setup
• [X] Error Handling
• [X] Decoder Selection
• [X] Output Audio Format
• [X] File Input and Decoding
• [ ] Position and Seeking
• [ ] Volume and Equalizer
• [ ] Status and Information
• [ ] Metadata Handling
• [ ] Advanced Parameter API
• [X] Low Level I/O

Overall the biggest change is in the naming: the mpg123 prefix has been removed and complete words are favored. mpg123_init becomes initialize (with R6RS prefixes it’s trivial to make it mpg123:initialize). Additionally, snake case is being used for multi-word names. Lastly, because of the removed prefix, generic name’s like open, read, and write, were given more specific names, open-stream, read-stream, and write-stream respectively

Some functions have API’s which aren’t super friendly to the “Scheme way”, and would have required consumers of the library to manually allocate and reference memory. Functions with different API’s are outlined here.

Get format has been turned into a continuation-passing-style (CPS) function:

(mpg123:get-format handle (lambda (rate channels encoding) ... ))

with rate channels and encoding then made available inside the lambda.