The desired limit, in bits per second, of network bandwidth consumption for this item.
- iOS 8.0+
- macOS 10.10+
- tvOS 9.0+
preferred to non-zero to indicate that the player should attempt to limit item playback to that bit rate, expressed in bits per second.
If network bandwidth consumption cannot be lowered to meet the
preferred, it will be reduced as much as possible while continuing to play the item.