mplibmad

A Project to enable the use of libmad in MicroPython.

Building

Dependencies:

• 'MPY_DIR' needs to be set to the location of micropython, or will assume it's relative location
• 'PICO_SDK_PATH' needs to be set, if you are building for rp2

Commands:

• make

Architecture

you will need to set an appropriately defined 'ARCH' variable,

I have tested building using ARCH=...

• x64 (unix port on ubuntu WSL)
• armv7emsp (Pi Pico 2 W)
• ...

Once the dependencies are in place, you could use make, or a build script for your architecture:

• build_rp2.sh

libmad

libmad is a mp3 decoder, that ceased development in 2004, archived at https://www.underbit.com/products/mad/

Many people have ported it to different environments over the years. This is my attempt to make it suitable for MicroPython, to run on microcontrollers.

Test Results

Stats

after optimizing pcm sample sizes:

• code size: 65936
• decode time: 180 seconds
• alt decode time: 93 seconds (no write to sdcard)
• implies 87 seconds are spent writing 10 megabytes out to the sdcard

first optimizations, on a pico2 aka armv7emsp:

• code size: 66438 up 100 from 66358
• decode time: 182 seconds, down from 480 seconds

Results

as of this commit, the code:

• compiles clean
• successfully runs test.py on unix and pico2
• successfully runs decode.py on unix and pico2
• the output.wav file generated is byte-for-byte the same on the unix port and pico2