PDF documents and multimedia e-books

Abstract This paper introduces the structure and generation tools of PDF documents, describes the problems of the production, management and copyright protection of multimedia electronic books in PDF format, and proposes that the electronic books in PDF format should become one of the collection goals of the library.
Keywords PDF document multimedia e-books e-books

PDF (Portable document Format Structured Document Format) An electronic document format developed by Adobe (http://www.adobe.com/adopports/) that allows text, fonts, formats, colors, graphic images, hypertext links, sounds, etc. Information such as dynamic images is packaged in a file. PDF evolved from the page description language PS (Postscript) and has almost the same page description capabilities and similar description methods as PS. However, unlike PS, PDF can also describe features such as interactive features (such as hyperlinks, interactive forms, etc.), page random access, and font emulation. Therefore, PDF is not only suitable for print publishing, but also suitable for electronic publishing. PDF also has its own obvious advantages compared to the HTML language that currently dominates electronic publishing. HTML can not describe the layout, but PDF can describe the beautiful layout; information inconsistencies often appear in HTML pages (such as different platforms, different browsers, different web browser windows see the same web page looks different), and This problem does not exist in PDF; HTML pages need to save additional images when saving, and PDF documents can be saved in one step. PDF not only has the advantages of both PS and HTML, but also overcomes their shortcomings, thus achieving the unity of paper printing and electronic publishing. If the typesetting content is generated as a PDF file, it can be released online while delivering the print.
1 PDF structure
PDF documents are constructed through a series of object sequences. PDF objects include Direct Objects and Indirect Objects. Indirect objects are identified PDF objects. Direct objects usually have Boolean, Number, String, Name, Array, Dictionary. Basic types such as null, stream, and stream. A PDF document contains one or more pages, and each page can contain documents, graphics, and images. A typical PDF file contains 4 parts, namely: file header, file body, cross-reference table, and file tail. The header is located on the first line of the PDF document. It indicates the version of the PDF specification used by the current file. The Body includes a sequence of indirect objects that make up the file. These objects represent the various components of the document. Examples are fonts, page trees, images, etc.
A cross-reference table is an indirect object address index table set up to allow random access to indirect objects. It gives the entry address of all objects used in the current file, ie the byte offset. So that the system randomly accesses different objects; the Trailer contains the starting address of the cross-reference table and the total number of objects in it, the object number of the Catalog object in the document, and the security information such as encryption. It is provided based on the end of the file. The information PDF application can find the cross-reference table and the directory object of the entire PDF file, thus controlling the entire PDF document.
2 Making Multimedia E-books with PDF Document Generator
Due to the various advantages of PDF documents, it has become the new darling of the publishing industry. At present, most of the online electronic publications are distributed in the form of PDF documents. The PDF version of the e-book can retain the original version of the book, with illustrations and texts. It can be directly printed or downloaded, and has a full-text search function.
Currently, there are mainly three ways to create PDF-based multimedia e-books: The first method is to use a special PDF authoring tool software to produce; the second method is to convert files containing Postscript page description language into PDF files; The way is to use conversion tools to convert other format files (such as DOC, HTML, etc.) into PDF documents.
Adobe Adobe Acrobat 4.0 has introduced several PDF document development tools. Among them, Acrobat PDF writer can convert any format of the document into a PDF document, it is a simulated "print" driver that is called in the client application (such as word97) print command, "print" file to create PDF The format of the document. The PDF writer is used by installing the software first. After the installation is completed, the PDF writer will be added to the column of the Windows printer settings; then start the application and open the file for conversion. Select “Print” in the menu or toolbar. ; Select PDF writer on the printer name menu; then select the target directory and name the PDF file; after completing the corresponding information, the PDF writer will automatically generate the PDF file. Acrobat Distiller is a high-end PDF document generator that can be used to create and edit PDF files. It can be used to convert Postscript files into PDF documents. Acrobat PDF maker is a series of tools. For example, Acrobat PDF maker Forword 97 can directly convert the edited DOC file into a PDF document in word97. In the conversion process, PDF maker will convert some of the information and structure in the word file accordingly. The information and structure in the PDF document, such as converting the head in word into a PDF bookmark, converting the URL in word into a PDF web link, and so on.
3 Reading and Managing Multimedia Electronic Books in PDF Format
At present, multi-media e-books in PDF format use Acrobat Reader 4.0 for reading. Acrobat Reader 4.0 is freeware and can be downloaded directly from the Internet at http://168.160.233.14/utility/ar40chs.exe. This file is a simplified Chinese version of the 4.0 version and has a file size of 14MB. Acrobat Reader can run either independently or as a browser plug-in to read PDF documents online. If Netscape is already installed on your computer, the installer will automatically insert it as a plug-in to Netscape when you install Acrobat Reader 4.0; if you are using Internet Explorer, you should install it after the program is installed. , Copy the nppdf32.Dll file from the directory "\Adobe\Acrobat\4.0\Reader\browser" to the Internet Explorer plugin directory "\InternetExplorer\Plugins\" and restart the computer so that it can be viewed in the browser. HTML web pages are as easy to navigate as PDF documents.
Acrobat Reader 4.0 provides users with multiple forms of browsing windows, such as "single page", "page + bookmark directory" and "page + page icon", which can be viewed in full screen or single page. Also provides a powerful page turning function, can use the menu, scroll bar, right-click menu, arrow keys, etc. to page, you can choose the first end, before and after and specified page number page; Acrobat Reader4.0 page multi-level zoom function to the user You can zoom from 12.5% ​​to 1600% to select the right size to read; at the same time, it also provides the function of copying. Click the “Text Select Tool” button with the “T” in the toolbar and drag the mouse to select The copied text content can be copied. It should be noted that if the security of "Text and graphics are not allowed to be selected" is set when creating a PDF document, the text cannot be copied.
Acrobat Reader 4.0 is a good choice for us to read multimedia e-books in PDF format. However, if we want to edit and modify the content, we should use Adobe's other product, Adobe Exchange. We can use it to add documents to the document. Hypertext links, bookmarks, small page icons, tables, etc. You can also insert, delete, copy, or move one or more pages in a document.
At present, many libraries in China have opened up their own multimedia reading rooms. The author believes that multimedia e-books in the PDF format should be one of the major sources of books. The library can be downloaded or purchased from the Internet. After being catalogued and indexed, the library can be organized into an electronic library to provide readers. It can also be used to create an electronic publication in PDF format using its own collection of books. The e-books that have been electronically converted into a common format will be converted into PDF format, which will give full play to the features of small, easy-to-transmit and store PDF files, and provide readers with a large number of electronic books with rich content and illustrations. In short, with the rapid development of information technology, paper-based books should gradually withdraw from their dominant position. Libraries should focus more on e-books, break through traditional methods and modes of book organization, and collect e-books. Organize and organize into daily work. The PDF format of e-books should become the mainstream of e-books because of its extensive application.
4 Copyright issues
Because the PDF document is easy to transmit and can be browsed freely after obtaining the free reading software, the copyright protection of the PDF format electronic book brings a great challenge. In response to this problem, Adobe has launched a secure publishing system for publishers and publishers. The system consists of two parts: the Web Buy plug-in for Adobe PDF Merchant and Acrobat Reader. PDF Merchant is a server-side program and Web Buy plug-in is a client program that works together to ensure that online publications are protected from piracy. PDF Merchant adds a “lock” to the PDF file to be sent. When readers try to use Acrobat Reader to read the “locked” file, they will see a message saying that you do not have permission to read the file, and ask if you would like to purchase it. The contents of the document, after you click to purchase, PDFMerchant will take you directly to the publisher or publisher's site. After the purchase is completed, the website will be accompanied by Acrobat Reader to send the file content and reading permission to your computer.
Of course, this system is only for publishers and publishers. How the library protects its rights and blocks the piracy loopholes. At present, there is no ready-made solution, but the above security system provides us with ideas. The library can also emulate the method of adding “locks” to PDF-based e-books. When a web user downloads and reads the e-books, the user is required to enter relevant information (such as the number of the library card, etc.) and promise not to use the book. For commercial use, then display the content.
5 Concluding remarks
The popularity of PDF documents in the distribution and digitization of electronic documents is not accidental. It is backed by a series of advantages. With the advent of more and more PDF documents on the Internet, its scope is no longer limited to e-books. Many product descriptions, electronic newspapers, corporate advertisements, web materials, and e-mails are all made into PDF documents. Therefore, libraries should This new thing pays full attention to it and incorporates it into its own information resources system. It discusses the ways and methods of collecting, organizing, managing, and providing the use of information to better serve readers.