recording video produced corrupted video
Hi,

I recently updated my homebridge-dafang package and everything seemed to be running great but it was only when I checked out my saved videos that I noticed something was wrong.  I have a HomeKit automation to trigger a 2 minute record video when the motion sensor is triggered.

All the videos were corrupted with the first 10-20 lines is fine (OSD) but the rest of the frame is garbled.

![image](https://user-images.githubusercontent.com/46592290/70369496-44f8db00-1888-11ea-8beb-f80e58f68e89.png)

I tried running ffmpeg to capture the stream to a file manually and it actually works fine.  Also viewing the stream in the home app is also fine.

I haven't changed anything in my config.json but I've tried changing various settings in the videoconfig section to no avail.  

Any ideas?

Thanks!!!