Decodes the next packet and calls all registered {@link IMediaListener}objects.
If a complete {@link IVideoPicture} or {@link IAudioSamples} set aredecoded, it will be dispatched to the listeners added to the media reader.
This method will automatically call {@link #open()} if it has notalready been called, and will automatically call {@link #close()} whenit reads an error or end of file from the file. The default close behavior can be changed with {@link #setCloseOnEofOnly(boolean)}.
@return null if there are more packets to read, otherwise return an IErrorinstance. If {@link IError#getType()} =={@link com.xuggle.xuggler.IError.Type#ERROR_EOF} then end of filehas been reached.