Library Metadata Rewrite Using Taglib

Summary

Status: This specification is in drafting. Feel free to add ideas to this page.

Mixxx's metadata parsing is error prone, does not always handle encodings properly, and doesn't support all tag formats for a given container. This design document describes an effort to replace all of Mixxx's current format-specific metadata parsing code with the use of TagLib, a cross-platform library that provides an all-encompassing API for parsing many different metadata formats. Currently it supports both ID3v1 and ID3v2 for MP3 files, Ogg Vorbis comments and ID3 tags and Vorbis comments in FLAC, MPC, Speex, WavPack and TrueAudio files.

Metadata to Extract

The new metadata extraction system will extract the following metadata from every file regardless of file format:

Artist
Title
Album
Comment
Genre
Year (integer)
Track Number (integer)

Additionally, the system must extract the following properties of each audio file for use in the GUI to present to the user and for use by the Mixxx engine to calculate

Work Breakdown

This work breakdown structure (WBS) will become more detailed as the design above becomes more thorough and complete.

1 Use TagLib to process the metadata of every file format we support
  1.1 Implement parsing for TagLib's generic Tag interface.
  1.2 Implement custom parsing for ID3v2 tags
  1.3 "" APE tags
  1.4 "" Xiph comment tags
  1.5 "" MP4 tags
2 Verify that nothing broke
  2.1 Verify new duration handling works
    2.1.1 In particular check MP3 VBR files
  2.2 Get a copy of every file format we support with a BPM tag attached. Verify BPM loads on library scan.
  2.3 Test the library on Albert's Library From Hell.