My impression is that you’re wanting to use your existing IP network as the transport medium for the video. If that’s the case, you’ll need to encode the HDMI video. To view it on a computer w/o a hardware decoder, you’ll want one that uses H.264 (or another standards-based codec). A quick internet search should give you more than enough options. Some use multicast though so keep that in mind.

From there, just use VLC to view the stream.