[Linphone-developers] freeswitch video conference's video-fps value and H264 decode

[Lost]

Client: Win7 X64+Linphone4.1.1
Server: Debian 8+Freeswitch1.6
Linphone Video codec use OpenH264, Freeswitch use default configuration.

Call 3500 from linphone.
The video is very not smooth, the Liphone "Received framerate" display < 1 FPS.
But when i change /etc/freeswitch/autoload_configs/conference.conf.xml "video-fps" to 25, Received framerate is become normal.
<profile name="video-mcu-stereo">
  <param name="video-fps" value="15"/> //change to 25
</profile>

I test every video-fps value and found if video-fps<23, the video become not smooth.
I also test Jitsi client and freeswitch, no such problem.
Is that an OpenH264 codec problem or bug?