improve audio quality

we have cdquality category, changed in /opt/freeswitch/conf/autoload_configs/conference.conf.xml - our template is FAIRTEACHINGconference.conf.xml in the cdquality section:

      <param name="rate" value="48000"/>
      <param name="interval" value="10"/>
      <param name="channels" value="2"/>
      <param name="energy-level" value="30"/>

(was 48000 / 20 (tried 50) / no channels line / 100)

/usr/local/bigbluebutton/bbb-webrtc-sfu/config/default.yml

tias_content: "2500000"
as_content: "2500"

maxaveragebitrate: "80000"
maxplaybackrate: "160000"

was:

tias_content: "1500000"
as_content: "1500"

maxaveragebitrate: "30000"
maxplaybackrate: "48000"

(both H264 and VP8, also giving more bandwidth for screen sharing)

and in /opt/freeswitch/conf/autoload_configs/opus.conf.xml

<configuration name="opus.conf">
      <settings>
        <param name="use-vbr" value="0"/>
        <param name="use-dtx" value="0"/>
        <param name="complexity" value="10"/>
        <param name="packet-loss-percent" value="8"/>
        <param name="keep-fec-enabled" value="1"/>
        <param name="use-jb-lookahead" value="1"/>
        <param name="advertise-useinbandfec" value="1"/>
        <param name="maxaveragebitrate" value="256000"/>
      </settings>
</configuration>

was:

<configuration name="opus.conf">
      <settings>
        <param name="use-vbr" value="1"/>
        <param name="use-dtx" value="0"/>
        <param name="complexity" value="5"/>

        <param name="packet-loss-percent" value="15"/>
        <param name="keep-fec-enabled" value="1"/>
        <param name="use-jb-lookahead" value="1"/>
        <param name="advertise-useinbandfec" value="1"/>
      </settings>
</configuration>