ITunes

Convert MP3 to Audio Book

 * 1) Configure Import
 * 2) * Edit > Preferences > Advanced > Importing
 * 3) * Make sure “Import Using” is set as “AAC Encoder“.
 * 4) * Change “Setting” to “Custom” and set the following options:
 * 5) ** Bit Rate: 64kbs (this is a nice average setting for most audiobooks)
 * 6) ** Channels: Stereo (fixes an issue with homemade mono files on some iPods)
 * 7) ** Check “Optimize for Voice“
 * 8) Convert Selection to AAC
 * 9) Rename the files with extension .m4a to to .m4b.
 * 10) * ls | awk '{print "mv \"" $0 "\" " "\"" $0 "\" " }' | sed 's/\.m4a/.m4b/2' | sh
 * 11) Import the new .m4b

Audio Book AAC Encoder Settings:
 * Details: 64 kbps (stereo), VBR, using voice filtering, optimized for MMX/SSE2.
 * Stereo Bit Rate: 64 kbps
 * Sample Rate: Auto (44,100 kHz)
 * Channels: Auto (or Stereo)
 * [x] Use Variable Bit Rate Encoding (VBR)
 * [ ] Use High Efficiency
 * [X] Optimize for voice

Default Custom AAC Encoder settings:
 * Details: 128kbps (mono)/256 kbps (stereo), VBR, optimized for MMX/SSE2.
 * Stereo Bit Rate: 256 kbps
 * Sample Rate: Auto
 * Channels: Auto
 * [x] Use Variable Bit Rate Encoding (VBR)
 * [ ] Use High Efficiency
 * [ ] Optimize for voice

Source: Turning MP3 audiobooks into iPod audiobooks · Dagon Design - http://www.dagondesign.com/articles/turning-mp3-audiobooks-into-ipod-audiobooks/
 * How to Convert Mp3s into Audiobooks with iTunes @ derek.broox.com - http://derek.broox.com/how-to-convert-mp3s-into-audiobooks-with-itunes/

Convert to MP3
Simple change the "Import Settings" to "MP3 Encoder", right click on the target music and "Create MP3 Version"

Edit -> Preferences -> General -> Import Settings

Remove Custom Background Colors in Play List
Under "iTunes" on the top left (between the Apple icon and "File" drop down), click "Preferences"

Select the "General" tab

Uncheck the box that says " Views: Use custom colors for open albums, movies, etc."

http://www.macobserver.com/imgs/tmo_articles/iTunes12_color_1.jpg

Reference:
 * https://discussions.apple.com/thread/7175188?start=0&tstart=0
 * http://www.macobserver.com/tmo/article/how-to-create-colored-backgrounds-for-playlists-albums-in-itunes-12