Add mod_audio_fork to FreeSWITCH's build alongside libwebsockets
(which mod_audio_fork depends on).
mod_audio_fork is used by the built in transcription feature as
a way to extract L16 streams from FreeSWITCH via WebSockets for further
processing by arbitrary transcription servers.
For full details on mod_audio_fork itself, please check drachtio's
source repo: github.com/drachtio/drachtio-freeswitch-modules.git
A few cautionary tales about this one:
- The new patch (mod_audio_fork_build.patch) guarantees libwebsockets
is properly linked to FreeSWITCH and that mod_audio_fork is built as
well. That's because mod_audio_fork is not an upstream module.
- The patch _may_ introduce conflicts on FreeSWITCH bumps more easily
than the other patches we have. They shouldn't be too hard to adapt,
though.
- There's fine tuning to be done to FreeSWITCH's unit file regarding
mod_audio_fork's capabilities. Again: check drachtio's repo.
Files are compressed on build, but gzip_static on isn't set on their
nginx route - so original files are being served, uncompressed.
This commit serves the previously compressed files instead (thus
reducing initial transfer size by ~1 MB).
Someone should look into whether serving compressed version of the rest
of assets makes sense - it probably does.
Still pending: fonts, locales, svgs, everything under resources, ...
Audio's callerId depends on the user name and there isn't
an "on-demand" way of fetching that field internally, making callerId
assembly with trusted attributes (server-side generated) impossible in
bbb-webrtc-sfu.
The new extra header (User-Name, mapped to user_name in the proxied
connection) allows fetching the user name field in a cheap way and
consequently provides a cheap+safe way of assembling the callerId.
Alternatives I've considered but discarded:
- a new akka-apps req-resp pair for fetching the user name (+overhead)
- a new akka-apps req-resp pair for generating the callerId (+overhead)
- piggybacking on GetMicrophonePermissionReq/Resp to generate the
callerId (same overhead, but mixing responsabilities)
