The invention provides a method and apparatus for cross-layer optimization in multimedia communications with different user terminals. The method that is intended for bidirectionally converting content and routing the content to different devices includes the following steps: receiving first multimedia content which originates from a first device that is disposed beyond a home location and takes asecond device which is disposed in the home location as a destination; converting the first multimedia content such that the second device can play the first multimedia content, and routing the converted first multimedia content to the second device; receiving second multimedia content from a third device which is in the home location and takes a fourth device which is disposed beyond the home location; and converting the second multimedia content such that the fourth device can play the second multimedia content and routing the converted second multimedia content to the fourth device. Respective optimizations of the delivery of the multimedia content in different channels are simultaneously supplied to a plurality of user terminals.