Double FPS

[spammy]

One of my monitors is a wyzecam V2 flashed with the firmware found here: https://github.com/EliasKotlyar/Xiaomi-Dafang-Hacks

It uses v4l2rtspserver which I've seen used elsewhere in these sort of things.

Most of mine run fine, but this particular one is being detected by ZM as having double the frame rate I'm setting. I can confirm the real fps using other rtsp clients (mpchc or VLC) and they all see 7, but ZM sees 15 or so, which results in double the HDD and shm usage.

Interestingly when viewing events, stepping through the frames count 7 for each second ticking in the camera's osd, so I feel there's some wastage here.

I suspect ffmpeg is misreading something, but is there anything I can do to correct it?