TX1 H.264 decode capability

I want to know the H.264 decode capability of TX1, the datasheet mentioned that TX1 can support 1080P@240fps, if that means I can decode 4 1080P@30fps video data simultaneously(consider 50% tolerance), please help, thank you.

Yes, TX1 can decode multiple streams simultaneously, generally speaking up to the aggregate rate.
You can test it by launching multiple gstreamer pipelines at once. You can find example pipelines in the Multimedia Guide, located here: http://developer.nvidia.com/embedded/dlc/l4t-multimedia-guide-24-1