From TouchDesigner 088 Wiki

LIVE555 is a library for setting up RTSP streaming servers for both audio and video.

Usage of LIVE555 is granted by the LGPL license, available for viewing here, as well as in the Touch folder in TouchDesigner's installation directory.

For builds starting at 31520 of version 088, the source for live555 can be obtained from our GitHub page.

For any earlier build the source can be downloaded from here.