Two way can play rtsp live video to html5, but both need gateway to tranfer the rtsp real stream to the format html5 can use, and do not need transcode.
a. media source extensions
Need a websocket gateway to repack the rtsp H264 stream to mp4 box.
b. WebRTC
Send the RTSP H264 data to WebRTC
More detail you can refer https://linkingvision.com/rtsp_in_html5_with_low_latency
