Update README.md

Updates to instructions and added Android notes.

Author: rbiresch

README.md

@@ -6,10 +6,11 @@ This repository contains script(s) to build ffmpeg for android with RTMP (and Op
 
 1. Install the [Android NDK][android-ndk] (tested with version r10).
 2. Ensure that [cURL][cURL] is installed.
-3. Clone this repository and `cd` into its directory.
-4. Run `build.sh`.
-5. Look in `build/dist` for the resulting libraries and executables.
-6. Look in `build/build.log` if something goes wrong.
+3. Ensure that [pkg-config][pkg-config] is installed.
+4. Clone this repository and `cd` into its directory.
+5. Run `build.sh`.
+6. Look in `build/dist` for the resulting libraries and executables.
+7. Look in `build/build.log` if something goes wrong.
 
 For example:
 
@@ -36,6 +37,56 @@ $ rm -rf src build .build-config.sh
 $ ./build.sh
 ```
 
+## Android
+
+To use `ffmpeg` with an Android app you will need to deploy the binaries along 
+with the libraries.  Here's a listing of the `build/dist` directory.
+
+```
+.
+├── bin
+│   ├── ffmpeg
+│   ├── openssl
+│   └── ssltest
+└── lib
+    ├── libavcodec-56.so
+    ├── libavdevice-56.so
+    ├── libavfilter-5.so
+    ├── libavformat-56.so
+    ├── libavutil-54.so
+    ├── libcrypto.so
+    ├── librtmp-1.so
+    ├── libssl.so
+    ├── libswresample-1.so
+    └── libswscale-3.so
+```
+
+A simple way to deploy the binaries would be to archive (e.g. zip) these directories
+and copy the archive in a res/raw directory within the Android project.  Then at runtime, 
+unpack the archive into a directory accessible to the app and set the appropriate permissions, 
+e.g. chmod 750 -R directory-name.
+
+In order for the Android app to use the libraries the LD_LIBRARY_PATH must be set to the location
+where the libraries reside.  For example:
+
+```java
+// Change the permissions
+Runtime.getRuntime().exec("chmod -R 0750 "+ abspath).waitFor();
+	
+//...
+    
+ProcessBuilder processBuilder = new ProcessBuilder(cmd);
+
+final Map<String, String> environment = processBuilder.environment();
+
+environment.put("LD_LIBRARY_PATH", context.getDir("lib", 0).getAbsolutePath());
+
+Process process = processBuilder.start();
+
+//...
+```
+
+
 ## Acknowledgements
 
 Inspired by: [openssl-android][openssl-android] and [FFmpeg-Android][FFmpeg-Android].
@@ -45,4 +96,5 @@ Inspired by: [openssl-android][openssl-android] and [FFmpeg-Android][FFmpeg-Andr
 [openssl-android]:https://github.com/guardianproject/openssl-android
 [FFmpeg-Android]:https://github.com/OnlyInAmerica/FFmpeg-Android
 [android-ndk]:https://developer.android.com/tools/sdk/ndk/index.html
-[cURL]:http://curl.haxx.se/
+[cURL]:http://curl.haxx.se/
+[pkg-config]:http://www.freedesktop.org/wiki/Software/pkg-config/