The details were revealed this week in a new patent application published by the U.S. Patent and Trademark Office and discovered by AppleInsider. Entitled "Local Storage of a Portion of Streamed Media Items," it describes a device like an iPhone having pieces of songs synced to it via iTunes.
Using this method, users could dramatically reduce the amount of storage used by their music library on their mobile device. Segments of the song would be stored locally, and the iOS software would fill in the gaps by obtaining the rest of the track from a file stored in the cloud.
Apple's application notes that with current streaming methods, a device must cache a sufficient amount of data for a media item. Only when enough of the file has been downloaded can streaming begin.
Earlier this year, Apple filed another cloud-related patent that described merging content from the cloud with a locally stored media library. This would seamlessly present both local files and those saved on the Internet in one list to users.
But Apple's more recent application notes that randomly jumping between content, as music listeners sometimes do, prevents the operating system from predicting the next song that will be played.
"When the electronic device is unaware of the next media item to play back, the electronic device can require undesired pauses between media items," the application reads. "Similarly, when a user skips to a different media item for playback, the electronic device can require a long pause during which no media item is played back as the new media item is streamed to the device."
Apple's solution would store only portions of media, such as songs, locally on a device like an iPhone. Using this method, the iOS mobile operating system would be able to immediately begin playback of a song from the locally saved data.
The system would then send out a request over the Internet for the exact same song, remotely stored elsewhere in its entirety. The system would then dynamically fill in the gaps and allow users to seamlessly listen to the song more quickly than if they were to stream the entire track.
The application suggests that the remotely stored content could be a user's own library, which they have streamed from a home computer or a remote server. Or, it could be streamed from a large "content source," such as the iTunes Music Store.
The described system would also utilize authentication methods, such as with an iTunes account username and password, to ensure that the user has purchased the items and has the right to stream them.
As for the syncing process, Apple's filing includes pictures that show an iPhone connected to iTunes via USB with the traditional "Music" pane open. Added is a new check box that reads "Sync partial music," allowing users to transfer those segments of songs.
Apple first filed for the proposed invention, which was made public this week, in November of 2009. It is credited to Allen P. Haughay and Benjamin Rottler.