Encoder libopus [libopus Opus]:
    Supported sample rates: 48000 24000 16000 12000 8000
    Supported sample formats: s16 flt
    Supported channel layouts: mono stereo 3.0 quad 5.0 5.1 6.1 7.1
libopus AVOptions:
-application       <int>        E...A. Intended application type (from 2048 to 2051)
   voip                         E...A. Favor improved speech intelligibility
   audio                        E...A. Favor faithfulness to the input
   lowdelay                     E...A. Restrict to only the lowest delay modes
-frame_duration    <float>      E...A. Duration of a frame in milliseconds (from 2.5 to 60)
-packet_loss       <int>        E...A. Expected packet loss percentage (from 0 to 100)
-vbr               <int>        E...A. Variable bit rate mode (from 0 to 2)
   off                          E...A. Use constant bit rate
   on                           E...A. Use variable bit rate
   constrained                  E...A. Use constrained VBR

