Part 1. Everything About iCloud Music Library and iTunes Match
What Is iCloud and iTunes Match
iCloud is a cloud storage and service provided by Apple. It enables you to store data such as documents, photos, music, movies on the server and get access to them via any iOS, Mac OS or Windows devices.
And the iTunes Match is part of iCloud service. It is special for uploading and managing music on iCloud. When matching your songs, if they are already in the iCloud Music Library, apple will enhance them to a better version with higher bit rate. If they don't exist, Apple will store them directly.
Why Audiobooks Are Not Valid for iCloud
As its name suggest, iCloud Music library is designed for music files. That is why the audibooks files with the formats AA, AAX, M4B are not supported. What's more, nowadays digital audiobook files you bought online are usually combined with DRM protection.
File Standards of iCloud Music Library
But what if you have already converted the audiobooks to MP3 but still get the error "This item is not eligible for iCloud"? Well, iCloud Music has very strict standards.
1. iTunes Match only supports AAC, MP3, AIFF, WAV, M4P, M4A, H.264, Apple Lossless and more. Among them, the AIFF, WAV, Apple Lossless will be converted to AAC files with 256Kbps. Files with specific formats which are not on the list won't be supported.
2. iCloud only supports the songs with bit rate higher than 96 Kbps, size small than 200Mb, length less than 2 Hours. For any audio files which doesn't meet the criteria, you can enhance the bit rate and reduce the file length and size.
3. It won't upload your DRM files from other sources unless it is the iTunes songs purchased before 2009. During upload, these DRM songs will be replaced with DRM free version.
4. iTunes Match is limited to 100,000 songs. Songs you purchased from iTunes are not counted towards the limit. But please make sure the iTunes Genius is turned on so that to detect your library well.