Syncing two streams

[Andrew Silby]

Hi, 

I have 2 computers with webcams which I capture via v4l2src and encode with gstreamer using x264enc and send to a 3rd computer using rtpbin. 

These streams sync well but if using the same parameters in x264enc but if I encode one stream with the zerolatency parameter and one without they are out of sync by around 1 second. I use ntp-sync=TRUE and rtcp-sync-send-time=FALSE as rtpbin parameters so I would have expected them to be in sync. Can you explain why they are out of sync and what I can do to keep them always in sync.

Below is the pipeline I have on each webcam computer:
V4l2src->x264enc->h264parse->rtph264pay->rtprtxqueue->rtpbin

Thanks very much,
Andy