# Compiling and Installing

## Package Repositories

Prebuilt packages for some newer releases of Debian are available on [this repository](https://dfx.at/rtpengine)

## Compiling on a Debian System

On a Debian system, everything can be built and packaged into Debian packages
by executing `dpkg-buildpackage` (which can be found in the `dpkg-dev` package) in the main directory.
This script will issue an error and stop if any of the dependency packages are
not installed. The script `dpkg-checkbuilddeps` can be used to check missing dependencies.
(See the note about G.729 at the end of this section.)

This will produce a number of `.deb` files, which can then be installed using the
`dpkg -i` command.

The generated files are (with version 6.2.0.0 being built on an amd64 system):

* `ngcp-rtpengine_6.2.0.0+0~mr6.2.0.0_all.deb`

	This is a meta-package, which doesn't contain or install anything on its own, but rather
	only depends on the other packages to be installed. Not strictly necessary to be installed.

* `ngcp-rtpengine-daemon_6.2.0.0+0~mr6.2.0.0_amd64.deb`

	This installed the userspace daemon, which is the main workhorse of rtpengine. This is
	the minimum requirement for anything to work.

* `ngcp-rtpengine-kernel-dkms_6.2.0.0+0~mr6.2.0.0_all.deb`

	Kernel module, DKMS version of the package. Recommended for in-kernel operation. The kernel
	module will be compiled against the currently running kernel using DKMS.

* `ngcp-rtpengine-kernel-source_6.2.0.0+0~mr6.2.0.0_all.deb`

	If DKMS is unavailable or not desired, then this package will install the sources for the kernel
	module for manual compilation. Required for in-kernel operation, but only if the DKMS package
	can't be used.

* `ngcp-rtpengine-recording-daemon_6.2.0.0+0~mr6.2.0.0_amd64.deb`

	Optional separate userspace daemon used for call recording features.

* `-dbg...` or `-dbgsym...` packages

	Debugging symbols for the various components. Optional.

For transcoding purposes, Debian provides an additional package `libavcodec-extra` to replace
the regular `libavcodec` package. It is recommended to install this extra package to offer support
for additional codecs.

To support the G.729 codec for transcoding purposes, the external library *bcg729* is required. Please
see the section on *G.729 support* below for details.

## Manual Compilation

There are 3 main parts to *rtpengine* plus one optional component, which can be
found in the respective subdirectories. Running `make` on the top source
directory will build all parts. Running `make check` additionally will run the
test suite.

* `daemon`

	The userspace daemon and workhorse, minimum requirement for anything to work. Running `make`
	will compile the binary, which will be called `rtpengine`. The following software packages
	including their development headers are required to compile the daemon:

	- *pkg-config*
	- *GLib* including *GThread* and *GLib-JSON* version 2.x
	- *zlib*
	- *OpenSSL*
	- *PCRE* library
	- *hiredis* library
	- *gperf*
	- *libcurl* version 3.x or 4.x
	- *libevent* version 2.x
	- *libpcap*
	- *libsystemd*
	- *spandsp*
	- *MySQL* or *MariaDB* client library (optional for media playback and call recording daemon)
	- *libiptc* library for iptables management (optional)
	- *ffmpeg* codec libraries for transcoding (optional) such as *libavcodec*, *libavfilter*, *libswresample*
	- *bcg729* for full G.729 transcoding support (optional)
	- *libmosquitto*
	- *libwebsockets*
	- *libopus*

	The `Makefile` contains a few Debian-specific flags, which may have to removed for compilation to
	be successful. This will not affect operation in any way.

	The transcoding feature can be excluded via a switch in the `Makefile`, making it
	unnecessary to have the *ffmpeg* libraries installed. The name of the `make` switch and
	its default value is `with_transcoding=yes`.

	`Makefile` switches can be provided to the `make` system via environment variables, for
	example by building with the shell command `with_transcoding=no make`.

* `kernel-module`

	Required for in-kernel packet forwarding. Supported for kernels versions 4.4 and newer.

	Compilation of the kernel module requires the kernel development headers to be installed in
	`/lib/modules/$VERSION/build/`, where *$VERSION* is the output of the command `uname -r`. For
	example, if the command `uname -r` produces the output `4.19-1-amd64`, then the kernel headers
	must be present in `/lib/modules/4.19-1-amd64/build/`. The last component of this path (`build`)
	is usually a symlink somewhere into `/usr/src/`, which is fine.

	Successful compilation of the module will produce the file `xt_RTPENGINE.ko`. The module can be inserted
	into the running kernel manually through `insmod xt_RTPENGINE.ko` (which will result in an error if
	depending modules aren't loaded, for example the `x_tables` module), but it's recommended to copy the
	module into `/lib/modules/$VERSION/updates/`, followed by running `depmod -a`.  This copying is performed
	on `make install`. After this, the module can be loaded by issuing `modprobe xt_RTPENGINE`.

* `recording-daemon`

	Optional component for the call recording feature. Prerequisites are
	usage of the kernel module and availability of transcoding (via
	*ffmpeg*)