The iTunes Store supports only the following uncompressed audio formats.
Format and corresponding file extension:
For Apple Lossless (ALAC), the QuickTime CODEC has been qualified. This is available through iTunes, iTunes Producer and QuickTime. All audio must be generated using a CODEC tested and approved by Apple.
For more information on codecs and the encoding process, see Mastered for iTunes.
Cover art should be at least 3000 x 3000 pixels, with an aspect ratio of 1:1, and delivered as high-quality JPEG or PNG files. Larger images are recommended.
A vendor identifier is a unique identifier used for music packages. Vendor identifiers can be numeric, up to 100 ASCII characters, and do not need to be a fixed number of digits. Apple recommends using the UPC of your album as the vendor identifier.