He buscado en internet y encontré esta biblioteca llamada "ffmpeg" que dice que es capaz de convertir GIF a MP4. Lo intenté pero no tuve éxito y obtuve una excepción.

https://github.com/guardianproject/android-ffmpeg-java

Si alguien sabe cómo convertir GIF a MP4 en la plataforma de Android, por favor ayúdame. Gracias

EDITAR

esto es lo que estoy haciendo usando ffmpeg lib anterior

String path = Environment.getExternalStorageDirectory()
                + "/gif/wall.jpg";
        String tmp = Environment.getExternalStorageDirectory() + "/gif/tmp";
        System.out.println(path);
        Clip clip = new Clip(path);
        File f = new File(tmp);
        try {
            f.createNewFile();
        } catch (IOException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
        try {
            FfmpegController controller = new FfmpegController(this, f);
            controller.convertImageToMP4(clip, 5,
                    Environment.getExternalStorageDirectory()
                            + "/gif/mynew.mp4", new ShellCallback() {

                        @Override
                        public void shellOut(String shellLine) {
                            // TODO Auto-generated method stub

                        }

                        @Override
                        public void processComplete(int exitValue) {
                            // TODO Auto-generated method stub

                        }
                    });

        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStack,Trace();
        }

obteniendo la siguiente excepción

10-09 14:39:59.638: W/System.err(19460): java.lang.NullPointerException: taintedCommand[7] == null
10-09 14:39:59.638: W/System.err(19460):    at java.lang.ProcessManager.exec(ProcessManager.java:184)
10-09 14:39:59.638: W/System.err(19460):    at java.lang.ProcessBuilder.start(ProcessBuilder.java:195)
10-09 14:39:59.638: W/System.err(19460):    at org.ffmpeg.android.FfmpegController.execProcess(FfmpegController.java:138)
10-09 14:39:59.638: W/System.err(19460):    at org.ffmpeg.android.FfmpegController.execFFMPEG(FfmpegController.java:102)
10-09 14:39:59.638: W/System.err(19460):    at org.ffmpeg.android.FfmpegController.execFFMPEG(FfmpegController.java:112)
10-09 14:39:59.638: W/System.err(19460):    at org.ffmpeg.android.FfmpegController.convertImageToMP4(FfmpegController.java:620)
10-09 14:39:59.638: W/System.err(19460):    at com.example.demo.MainActivity.onCreate(MainActivity.java:36)
10-09 14:39:59.638: W/System.err(19460):    at android.app.Activity.performCreate(Activity.java:5231)
10-09 14:39:59.638: W/System.err(19460):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
10-09 14:39:59.638: W/System.err(19460):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2148)
10-09 14:39:59.638: W/System.err(19460):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
10-09 14:39:59.638: W/System.err(19460):    at android.app.ActivityThread.access$800(ActivityThread.java:135)
10-09 14:39:59.638: W/System.err(19460):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
10-09 14:39:59.638: W/System.err(19460):    at android.os.Handler.dispatchMessage(Handler.java:102)
10-09 14:39:59.638: W/System.err(19460):    at android.os.Looper.loop(Looper.java:136)
10-09 14:39:59.638: W/System.err(19460):    at android.app.ActivityThread.main(ActivityThread.java:5001)
10-09 14:39:59.638: W/System.err(19460):    at java.lang.reflect.Method.invokeNative(Native Method)
10-09 14:39:59.638: W/System.err(19460):    at java.lang.reflect.Method.invoke(Method.java:515)
10-09 14:39:59.638: W/System.err(19460):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
10-09 14:39:59.638: W/System.err(19460):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
10-09 14:39:59.638: W/System.err(19460):    at dalvik.system.NativeStart.main(Native Method)