HDMI-CSI converter with GoPro Hero5, huge latency, what to do?

Help / Getting Started
1

I got now a OpenHD 2.0.0 system working, thanks also to some great help from here and the wiki (and of course the devs).

My goal is to use a GoPro Hero5 black as camera, and I got it essentially working with the well-known DCDZ HDMI-CSI converter card, but I get a huge latency of ca 4 secs or so.

I couldn’t find much info on this topic on the web, so I would appreciate any hint or insight.

I have the EIS disabled, since I found reports that this would be the issue. I also tried a variety of different resolutions, fps, and so on, but didn’t help, always 4secs (I think that this is expected, since I would think that the hdmi negotiates it’s own resolution etc).

What I observe is a large bitrate of ca 10 MBs. It actually frequently runs into the colors, from which I conclude that it’s actually touching the possible limits, which makes me think that this could be the reason for the big delay. If so, which parameters should I tweak?

Cheers, Olli

2

Cut BITRATE_PERCENT, it shouldn’t be riding the limit like that.

3

many thx, I’ll try

on the ground? on the air? or on both?

4

ok, this indeed seems to do the trick THANKS

I went down to 30. The bitrate is then something like 5-6 Mbps typically. Maybe I even use 25, to have some margin.

When I use a RPi CSI cam the bitrate is (with 60) actually higher than that, but I just got more disturbances with the gopro when I would use a percentage above 30. So, things do not exactly scale with that value.
(the bitrate displayed in the OSD is significantly higher than the calculated bitrate as shown in the status window for the gopro case)

for my curiosity, could you explain why that happens in the first place?

I mean, for both cameras, the hd,i-cis-gopro and the RCPI-CSI-cam I see in the status window that the air resolution is set to 1280x720@30, so I would have naively thought that therefore the bitrate of the video stream which is input into the wbc tx should be about similar in both cases … which it obviously is not, but why?

many thx
Olli

BTW: the smartsync may need some improvement. At least from what is displayed in the status window it can happen that the configuration of the air is done while the smartsync is downloading, from which I would speculate that it can happen that the air uses some still old values.