Default ONVIF 'Maximum FPS' causes video glitches

[jburgess777]

After setting up my ONVIF Netvis TH661 camera using the default settings I found that SD video occasionally glitched, triggering frequent alarms. When using HD I would only ever get the top 1/4 of the frame, the rest would be a smear.

The 'Maximum FPS' defaults are set to match the camera frame rate. Once I cleared this field everything worked much better. I think that when an ONVIF camera is detected it should leave the 'Maximum FPS' blank, or set it to something higher than the camera FPS.

When the maximum FPS is too low the zmc process calls nanosleep() to slow itself down. This then causes the receive queue (netstat Recv-Q) of the UDP sockets to fill and drop data (/proc/net/udp drops):

$ sudo netstat -alnp | grep zmc
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp       83      0 192.168.1.104:59683     192.168.1.246:554       ESTABLISHED 4915/zmc
udp   111872      0 0.0.0.0:34448           0.0.0.0:*                           4915/zmc
udp        0      0 0.0.0.0:34449           0.0.0.0:*                           4915/zmc
udp   131328      0 0.0.0.0:34450           0.0.0.0:*                           4915/zmc
udp        0      0 0.0.0.0:34451           0.0.0.0:*                           4915/zmc

$ cat /proc/net/udp                                                                                                                                
   sl  local_address rem_address   st tx_queue rx_queue tr tm->when retrnsmt   uid  timeout inode ref pointer drops                                                                          
   8: 00000000:8690 00000000:0000 07 00000000:0001DB00 00:00000000 00000000    48        0 1050936 2 ffff8800b9fc6400 13932                                                                  
   9: 00000000:8691 00000000:0000 07 00000000:00000000 00:00000000 00000000    48        0 1050937 2 ffff8800b9fc7400 0                                                                      
  10: 00000000:8692 00000000:0000 07 00000000:00009F00 00:00000000 00000000    48        0 1050938 2 ffff8800b9fc7000 1677                                                                   
  11: 00000000:8693 00000000:0000 07 00000000:00000000 00:00000000 00000000    48        0 1050939 2 ffff8800b9fc7c00 0                                                                      

[knight-of-ni]

Yes, this is a known issue with the MAX FPS fields, as indicated by the newly added help text.
We need to change the Onvif code so it does not populate either of those fields.