Configure and build PJSIP for Android

In this section, we will configure and build PJSIP as a native library for Android, and PJSUA2 API Java/JNI interface that can be used by Android Java and Kotlin applications.

Create config_site.h

Create pjlib/include/pj/config_site.h file with a text editor and set the contents to the following:

/* Activate Android specific settings in the 'config_site_sample.h' */
#define PJ_CONFIG_ANDROID 1
#include <pj/config_site_sample.h>

#define PJMEDIA_HAS_VIDEO 1

The rest of the configurations will be set by the configure script below.

Configuring PJSIP 

Using OPENSSL_DIR and OBOE_DIR environment variables that we set earlier in the previous page, run the configure commands below, replacing the Android NDK path with the correct path:

$ cd /path/to/pjproject
$ export ANDROID_NDK_ROOT=/home/whoever/Android/android-sdk/ndk/28.0.12916984
$ ./configure-android -with-ssl=$OPENSSL_DIR --with-oboe=$OBOE_DIR

Using the default setting will build NDK’s default target architecture (currently arm64-v8a). See next section for building other targets.

Tip

On MinGW32/MSys, use absolute path format D:/path/to/android/ndk instead of /D/path/to/android/ndk for ANDROID_NDK_ROOT.

Tip

The ./configure-android is a wrapper that calls the standard ./configure script with settings suitable for Android target. Standard ./configure options should be applicable to this script too.
Please check ./configure-android --help for more info.
Other customizations are similar to what is explained in Building with GNU Tools/Autoconf page.

Specifying Android API level 

Specify the Android API level target in APP_PLATFORM. For example:

APP_PLATFORM=23 ./configure-android --with-ssl=$OPENSSL_DIR --with-oboe=$OBOE_DIR

Note

Some features may require a specific minimum API level. For example:

Third party libraries that use stdout and stderr (e.g: OpenSSL, OpenH264) may not be detected properly by the configure on API level below 23.
Native Android audio & video codecs require API level 28 or higher.

Note

If you build third party libraries from the source (such as OpenSSL), you need to rebuild them for the same API level as well.
If you have built PJSIP for other API level, it’s recommended to clean it up first before running configure above:
```
$ cd /path/to/pjproject
$ make distclean
```

Configuring for other architectures (including emulator)

Specify the target arch in TARGET_ABI and run it with --use-ndk-cflags. For example, for targetting the emulator:

TARGET_ABI=x86_64 ./configure-android --use-ndk-cflags ...

Note

If you build third party libraries from the source (such as OpenSSL), you need to rebuild them for the same architecture as well.
If you have built PJSIP for other architecture, it’s recommended to clean it up first before running configure above:
```
$ cd /path/to/pjproject
$ make distclean
```

Supporting 16 KB page sizes (Android 15)

As described in Android official doc, Android from version 15 onwards supports devices that are configured to use a page size of 16 KB (16 KB devices).

In order for PJSIP to support flexible page sizes (both 4 and 16 KB), you need to use NDK r27 or later and apply https://github.com/pjsip/pjproject/pull/4068. Alternatively, you can manually specify the build flags to the configure script:

CFLAGS="-D__BIONIC_NO_PAGE_SIZE_MACRO" LDFLAGS="-Wl,-z,max-page-size=16384" ./configure-android

Verifying configuration 

Now we need to check that all the intended features are detected by ./configure-android script by observing the configure output:

Check that OpenSSL is detected and enabled:

checking for OpenSSL installations..
checking for openssl/ssl.h... yes
checking for ERR_load_BIO_strings in -lcrypto... yes
checking for SSL_CTX_new in -lssl... yes
OpenSSL library found, SSL support enabled

Check that Oboe is detected and enabled:

checking Oboe usability... yes
Checking sound device backend... Oboe

Building PJSIP 

Now we can build PJSIP with:

$ make dep && make clean && make

Building PJSUA2 Java interface with SWIG 

Set JAVA_HOME environment variable to the directory containing javac executable. Since we have installed Android Studio, I find this to be the easiest:
```
$ export JAVA_HOME=/path/to/android-studio/jbr/bin
```

Build the SWIG interface:

# In pjproject dir
$ cd pjsip-apps/src/swig
$ make

This produces the following artefacts:

pjsip-apps/src/swig/java/android/pjsua2/src/main
├── jniLibs/<ARCH>
│   ├── libpjsua2.so
│   └── libc++_shared.so
├── java/org/pjsip/pjsua2
│   └── *.java

Copy third party native libraries 

You need to manually copy third party native libraries that are used by PJSIP to jniLibs/$ARCH directory of the Android application so that they are packaged with the application. So far we have added OpenSSL and Oboe as our dependencies, so we will copy them. Follow the steps below.

Go to the directory of your Android application (the directory that has build.gradle file and that needs the native libs), for example pjsip-apps/src/swig/java/android/pjsua2/.

Set the arch which you want to copy.

# Replace ARCH with arm64-v8a, x86_64, or whatever arch
$ export ARCH=arm64-v8a
$ cd src/main/jniLibs/$ARCH

Copy OpenSSL libs:

$ cp -v $OPENSSL_DIR/lib/*.so .
'/home/whoever/Android/openssl-3.4.0/lib/libcrypto.so' -> './libcrypto.so'
'/home/whoever/Android/openssl-3.4.0/lib/libssl.so' -> './libssl.so'

Copy Oboe libs:

$ cp -v $OBOE_DIR/prefab/modules/oboe/libs/android.$ARCH/*.so .
'/home/whoever/Android/oboe-1.9....oid.arm64-v8a/liboboe.so' -> './liboboe.so'

Check the libraries to be packaged:

$ ls
libcrypto.so  libc++_shared.so  liboboe.so  libpjsua2.so  libssl.so

What’s next 

The PJSIP library, the JNI interface, and the third party libraries are ready. Now we are ready do build the sample applications.