PJSIP library is modified to capture PCM frames from the call and stream PCM frames to the calls.

Added two classes to media.hpp and media.cpp files:

• AudioMediaCapture: contains list to accumulate incoming frames, frames can be extracted with getFrames/getFramesAsString methods.
• AudioMediaStream: contains list for outgoing frames, frames can be populated with putFrame/putFrameAsString methods.

Need some changes to SWIG to access those features from the Python:

• Uncomment USE_THREADS = -threads -DSWIG_NO_EXPORT_ITERATOR_METHODS in swig/python/Makefile
• Add typemaps to swig/pjsua2.i to send/receive bytes from Python:

#ifdef SWIGPYTHON
  %typemap(in) (char *data, size_t datasize) {
    Py_ssize_t len;
    PyBytes_AsStringAndSize($input, &$1, &len);
    $2 = (size_t)len;
  }

  %typemap(in, numinputs=0) (char **data, size_t *datasize)(char *temp, size_t tempsize) {
    $1 = &temp;
    $2 = &tempsize;
  }

  %typemap(argout) (char **data, size_t *datasize) {
    if(*$1) {
      $result = PyBytes_FromStringAndSize(*$1, *$2);
      free(*$1);
    }
  }
#endif

1. docker-compose up
2. docker-compose exec pjsip python demo.py Demo script dumps frames to from the call to pjsip/pjsuademo/output.lpcm and streams hw.raw to the call. The recording of the call with both parties will be in asterisk_files/recordings directory.