[core] Fixed buffers avg size calculation
[core] Fixed buffers avg size calculation

Haivision/srt,Haivision/srt,ethouris/srt,Cinegy/srt,Cinegy/srt,ethouris/srt,ethouris/srt,Cinegy/srt,Haivision/srt,ethouris/srt,Haivision/srt,Cinegy/srt