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[eschmidbauer at gmail.com]

in opus.conf.xml what is the difference between adjust-bitrate and use-vbr ?
doesn’t variable bit rate (vbr) adjust the bitrate? or do you need both enabled for that to actually work?
or do they contradict each other? 
Any info on this would be greatly appreciated and i would love to document the answer on confluence
https://freeswitch.org/confluence/display/FREESWITCH/mod_opus

[dragos at freeswitch.org]

"use-vbr" will configure the encoder in VBR mode - which is the opposite of CBR . This happens once during the call, when the encoder is initiated, and the payload for each packet will have different sizes based on the audio input.  "adjust-bitrate" enables a feature in FS that will pass certain information to the opus module during the call and the bitrate of the encoder will be modified based on packet loss / RTT .  


Dragos


On Mon, Nov 2, 2020 at 3:18 PM E. Schmidbauer <eschmidbauer@gmail.com (eschmidbauer@gmail.com)> wrote:

[eschmidbauer at gmail.com]

Thanks for the clarification!
I'm curious about the implementation of `adjust-bitrate` 
How does freeswitch actually adjust the bitrate of a live call? Does freeswitch send a RE-INVITE w/ SDP changes or some other way that I cannot think of?
Thanks,Emmanuel





On Mon, Nov 2, 2020 at 1:49 PM Dragos Oancea <dragos@freeswitch.org (dragos@freeswitch.org)> wrote:

[dragos at freeswitch.org]

It has nothing to do with RE-INVITE or SDP, it just increases/decreases the bitrate of the encoder dynamically based on a logic that takes into account an estimation of future loss and rtt and also sudden changes of these values - core tells the module what to do. Basically we try to make the difference between congestion and "slow link" and adjust the bitrate, we decrease slowly or we go to minimum bitrate. 



On Fri, Nov 6, 2020 at 4:01 PM E. Schmidbauer <eschmidbauer@gmail.com (eschmidbauer@gmail.com)> wrote: