Yet another MPEG-2 Part 3 decoder

An attempt at an MPEG-2 Part 3 decoder in Rust.

This is a toy project, use at your own risk!

Supported layers

• Layer I (MP1)
• Layer II (MP2)
  • Multichannel
• Layer III (MP3)

Roadmap

1. Find a simple reference implementation
   • It should be in C and contain as few as possible assembly and no threading
   • It should have a compatible license
   • It should have a test suite
   • It should be simple to read and port (no assembly, no complex SIMD)

2. Compile the reference implementation as submodule with Cargo
3. Make the reference implementation callable from Rust (C2Rust?)
4. Reimplement each component and compare with reference implementation

Layer I being so simple, a reference implementation may not be needed.

Personal goals

• Learn Rust
• Learn MP3 file format
• Learn audio signal processing

Safety goals

• Use safe Rust as much as possible
• No explicit panic

Features

• Dump MPEG-2 structure
• Dump MPEG-2 packets
• Output PCM

Test goals

• 100% test coverage
• Compare struct dump to reference
• Compare packets dump to reference
• PCM output is identical to reference excluding rounding errors
• Stretch: Assembly generated never calls panic!

Reference should be generatable from fmprobe and ffmpeg.

Existing implementations

Implementation	SIMD	Layer	License	ISO	Note
Jon Olick's	[ ]	I	Public	[?]	archive
PDMP2	[ ]	II	Zlib	[?]
mp3-decoder	[ ]	III	GPL	[ ]
minimp3	[X]	All	CC0	[X]
libmad	[X]	All	GPL	[X]
PDMP3	[ ]	All?	CC0	[?]
TwoLame	[?]	II	LGPL	[X]	Encoder only

Interesting links

• Let’s build an MP3-decoder!
• Inside MP3
• Inside the MP3 codec
• minimp3 interesting links
• PDMP3 interesting links