Not the same! A song in a commercial CD usually/ normally was stored in an AIFF format. If you imported/ converted this song into an AAC format, then there will be some quality lost. And, if you then export/ convert this song (from AAC format into AIFF), that lost part is never be regained; the later AIFF song is not the same with the first(original) one.
If the song from iTunes is protected then it cannot be imported into Garageband but other song files in the MP3, AAC, WAV or AIFF format can be dragged into Garageband's timeline to import them.
No, they get copied
Music files downloaded from the iTunes store come in the format "Purchased AAC", and video files downloaded from the iTunes store come in the MP4 format
iTunes can format songs into a variety of different formats. By default the songs are encoded in AAC, short for Advanced Audio Coding. It is much like MP3, but sound quality is better. On the other hand not many Digital Audio Players accept AAC; however many are beginning too.
They need to be the right format. look up on the internet what formats are supported by itunes.
If the song from iTunes is protected then it cannot be imported into Garageband but other song files in the MP3, AAC, WAV or AIFF format can be dragged into Garageband's timeline to import them.
Right click on the track you wish to convert in your iTunes music library and then select Create AAC Version from the menu that appears.
Assuming that the movie has been downloaded from a source other than iTunes and you now wish to add it to the iTunes library you will need to check that the movie is in a format recognised by iTunes.
The song gets imported to iTunes
Movies from iTunes are delivered in the H.264 format which is subset of the MPEG-4 format.
To add a movie in a suitable format from your Mac to your iTunes library you can either drag it onto the iTunes icon in the Dock; drag it into the Library section (top left corner) of the iTunes window, or select Add to Library... from the iTunes File menu.
The old version of iTunes does not need to be deleted as the new version will update it to the latest version.
The Harry Potter audio book collection on iTunes typically takes up around 9-10 GB of memory due to the length and high quality of the audio files. This estimate can vary slightly depending on the specific format and version of the audiobooks.
The MP3 format was introduced in 1995 and the iTunes software appeared in 2001.
itunes 9
Digital audio files are a compromise between sound quality and file size. You can set the quality in the Import Settings option in the General settings of the iTunes preferences. Using AIFF format and the 44.1Khz 16 bit sample rates will give you CD quality but a large file size. The AAC format on the iTunes Plus setting will give you good audio quality and a relatively small file size. If these are not original CDs and have already been compressed then you are degrading the already reduced audio quality when you import them and re-compress them.
When installing a new version of iTunes only the iTunes software is updated your library is not touched.