Unable to build GStreamer tutorials using Android Studio

Question

I am trying to build the tutorials that are bundled with gstreamer-sdk-android-arm-debug-2013.6. The Android.mk file in the src/jni directory (tutorial 1 project) references environment variables such as GSTREAMER_SDK_ROOT. From what I have read, Android Studio does not use/pass environment variables to the build scripts. Is there a best practice for modifying makefiles and for defining/retrieving the key/value pairs required by the build scripts?

Mullane

Android Studio can't work with Makefiles, so you'll have to set up Gradle build files if you want to use it as anything more than a text editor. – Salamis

I am using makefiles with Android Studio for the ndk component in other projects, such as mupdf and it works fine. The only issue I see is with these environment variables used by the Android.mk for the GStreamer tutorials. I could hard code the values in the Android.mk files and I'm pretty sure it would build - but I'm guessing there is a better way. – Mullane

That said, if there is a way to convert these tutorials to use only Gradle build files, I'd be all for it - but don't know where to start. – Mullane

Answer 1

Ok, I have a working solution. You CAN pass environment variables to ndk-build (or any other process spawned by gradle Exec). In my case, I wanted to set these for both the clean and build tasks. This is is done using tasks.withType(Exec). The environment parameter is set here for all Exec tasks.

For GSTREAMER_SDK_ROOT, I added an entry to local.properties:

gst.dir=/Users/svenyonson/sdk/gstreamer-sdk-android-arm-debug-2013.6

For PATH, I used the default for the spawned process and added in what I needed.

Here is a working version of build.gradle:

apply plugin: 'com.android.application'

android {
    compileSdkVersion 19
    buildToolsVersion "20.0.0"

    defaultConfig {
        applicationId "com.gst_sdk_tutorials.tutorial_1"
        minSdkVersion 19
        targetSdkVersion 19
    }

    sourceSets.main {
        jni.srcDirs = []
        jniLibs.srcDir 'src/main/libs'
        java.srcDirs += 'src/main/jni/src'
    }

    tasks.withType(Exec) {

        def localProperties = new Properties()
        localProperties.load(project.rootProject.file('local.properties').newDataInputStream())
        def gstDir = localProperties.getProperty('gst.dir')

        environment = [:]
        environment['PATH'] = System.getenv("PATH")+ ":/usr/local/bin"
        environment['GSTREAMER_SDK_ROOT'] = gstDir
    }


    task buildNative(type: Exec, description: 'Compile JNI source via NDK') {

        def ndkDir = project.plugins.findPlugin('com.android.application').getNdkFolder()
        commandLine "$ndkDir/ndk-build",
            '-C', file('src/main/jni').absolutePath,
            '-j', Runtime.runtime.availableProcessors(),
            'all',
            'NDK_DEBUG=1',
            'V=1',
            'APP_PLATFORM=android-19'

    }

    task cleanNative(type: Exec, description: 'Clean JNI object files') {
        def ndkDir = project.plugins.findPlugin('com.android.application').getNdkFolder()
        commandLine "$ndkDir/ndk-build",
            '-C', file('src/main/jni').absolutePath,
            'clean'
    }

    clean.dependsOn 'cleanNative'

    tasks.withType(JavaCompile) {
        compileTask -> compileTask.dependsOn buildNative
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
        }
    }
}

The project now builds and runs. The only other things you will need to do is add ndk.dir to local.properties:

sdk.dir=/Users/svenyonson/sdk/android-sdk
ndk.dir=/Users/svenyonson/sdk/android-ndk-r9d
gst.dir=/Users/svenyonson/sdk/gstreamer-sdk-android-arm-debug-2013.6

One more thing: These examples will not build using android-ndk-r10d. Be sure to use android-ndk-r9d.

Mullane