Play broadcast on a client request

[aimaicai]

Hi, I'm starting to use vlm from few days, I've searched everywhere but I wasn't able to find a recent solution to my problem. I have a lot of broadcast setted up on my vlm configuration file, every of them is fed up with an rtsp stream coming from a live ip camera. For every camera I have many other broadcast, one for every format I want to expose (flv, livehttp, webm etc). If I "control stream# play" all the broadcast, all work very well, except for the waste of cpu cause of the continuos unused transcoding. I know that its possible to play the broadcast selectivelly by using telnet or http interface, but I would like to know if there is an automatic way to do it, like play the broadcast on a client request, and stop it when the client doesn't need it anymore. If it is not possible, I would like you to share with me the best trick for accomplish my task.
Thank you, and sorry for my ugly english...