NullPointerException in MovieCreator.build

[GoogleCodeExporter]

I have Android app which uses mp4parser 1.0.2-SNAPSHOT for reading files. I am 
receiving the following crash reports from some devices:

java.lang.NullPointerException
       at com.googlecode.mp4parser.authoring.container.mp4.MovieCreator.build(SourceFile:48)
       at com.googlecode.mp4parser.authoring.container.mp4.MovieCreator.build(SourceFile:35)
       at ru.roadar.android.audio.Mp4ParserAudioMuxer.mux(SourceFile:57)
       at ru.roadar.android.video.VideoRecorder$VideoAudioMuxer.run(SourceFile:641)
       at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
       at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
       at java.lang.Thread.run(Thread.java:856)

In fact, it's possible for IsoFile.getMovieBox to return NULL, so it may be 
makes sense to add a guard against it.

Original issue reported on code.google.com by andrey.c...@gmail.com on 9 Jun 2014 at 8:36