The technique for the delivery of a media file is adjusted based on current constraints on a channel being used by a device requesting the media file. The media file is copied and the various copies are optimized for different constraints. Then, the media file is delivered by examining the current constraints on the channel and transmitting the media data from the copy of the media file that is most suitable for the current constraints. In some implementations, the constraint is the bandwidth of the channel and the copies of the media file are based on different bit rate adjustments.