CSipSimple-tmp

Fork & (dirty) fixes for CSipSimple, to make it work with 2021 tools & current API level.

Still work to do. If anyone reading this, please read to the end

Notes, NDK / JNI

• Compiles ( arm64-v8a + x86_64 ) with NDK r23b
• Video support (webrtc, libvpx) disabled (for now?), some external codecs (opus, silk) disabled as well.
• OpenSL-ES backend is hardcoded
  Somehow sideload of separate libpj_opensl_dev by pjsip lib doesn't work
  As result android_jni_dev audio backend cannot be used
• For hardware AEC, my dirty hack from 2014 still applies.
  See : https://code.google.com/archive/p/csipsimple/issues/2838
  So it is not guaranteed to work on all devices, however on Nexus/Pixel for many years it has been very stable.

Notes, Android java part

• API level 30
• Sherlock / supportv4 replaced by std android API. No use of androidx or support library.
  So minimum API level = 26
• Favorites fragment disabled (too complicated to migrate)
• Incallcontrols disabled, no DTMF, speaker, in-call settings for now. Might fix it eventually.

To build

• NDK_DIR to path, standard tools (make, quilt,...)
• SWIG 2.0 needed, hard to find RPM, compile 2.0.12 from source.
• First build native part : make
• Then build app APK using Android studio.

Bugs / Things to know

• As openSL + hardware AEC is hardcoded, no need for software echo cancel. By default : no echo cancel + sound clock to 48khz.
  Near-zero audio latency.
• Android permissions have to be applied manually after install !
  SIP will fail if permissions not granted one by one
  Access Settings > app > ...
• SIP service does not (always) resume when Wifi connectivity is back after a long out-of-wifi time

Todo ?

• use androidx / current support libraries
• implement android compliant permission requests
• use ConnectivityManager.NetworkCallback for connectivity queries
• Migrate InCall controls to std android API.