How MP3 CD players number the folders on an MP3 CD

Whenever you use an MP3 CD player to play an MP3 disc, the player begins by scanning the entire disc for MP3s. Every folder it finds that contains MP3s is assigned a folder number, and every MP3 in the folder is assigned a track number. This lets you access any song on the disc by specifying the folder number and the track number.

This document describes the order that MP3 CD players will search the disc and number the folders. A text-only version is also available.


Of the MP3 CD players I've experimented with I've discovered two different ways a player may scan the disc. This means an MP3 CD may have different folder numbers on different players. Here is an example layout I'll use to illustrate the two methods.

[example layout]

In the level scanning method, the player will search all the folders on the same level in the hierarchy before going to the next level down. Whenever a folder containing MP3s is found, it is assigned the next folder number in the sequence.

[level scanning]

In the depth scanning method, the player will search folders and sub-folders in order going down the hierarchy of the tree. Whenever a folder containing MP3s is found, it is assigned the next folder number in the sequence.

[depth scanning]

In both methods, the MP3s themselves are assigned track numbers in the order they are listed in the folder.

Notes


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Robert Hart
Revised Mar. 4, 2005