Synchronizing multi-cast receivers?

[Spruyt, Randy]

A general question,

With 1 multicast server and 2 receivers, both receivers using an NTP clock. The playback starts off synchronized, but drifts apart over time. The current theory is the rtpjitterbuffer is adjusting the PTS to account for volatility in the network. How would one ensure both playback receivers play the stream at exactly the same time (to the frame)? If a frame needs to be dropped that is fine, but the presentation time must remain the same on both.

Server:
gst-launch-1.0 -v filesrc location=/mnt/share/demo/BattleField4_1080p_60Hz.mp4 ! qtdemux ! rtph264pay ! udpsink host=224.1.1.1 port=5000

Receiver 1 & 2:
gst-launch-1.0 udpsrc port=5000 multicast-group=224.1.1.1 caps="application/x-rtp, media=video, clock-rate=90000, encoding-name=H264, sprop-parameter-sets=\"Z0LAHpp0A8ARPy4CIAAAfSAAOpgR4sXU\\\,aM4yyA\\\=\\\=\", payload=96, ssrc=3258400262, timestamp-offset\=1691038309, seqnum-offset=132" ! rtpjitterbuffer ! rtph264depay ! vaapiparse_h264 ! vaapidecode ! vaapisink

Thoughts?

Randy
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