Automated Document Conversion System for Simple ... - UVigo

This full text paper was peer reviewed at the direction of IEEE Communications Society subject matter experts for publication in the IEEE CCNC 2010 proceedings

Automated document conversion system for simple multimedia platforms R. P. Martínez-Álvarez, S. Costas-Rodríguez

F. J. González-Castaño, F. Gil-Castiñeira

Gradiant Vigo, Spain {rmartinez, scostas}@gradiant.org

Departamento de Enxeñería Telemática Universidade de Vigo Vigo, Spain {javier, xil}@det.uvigo.es

Abstract—Sharing documents across different platforms is highly necessary nowadays. However, many devices, as embedded ones, cannot deal with formats like PDF or PowerPoint, despite their widespread use. In this paper we propose an automated format conversion system to allow the visualization of formats that are not supported in simple multimedia embedded devices. Format conversion, multimedia, embedded devices.

I.

INTRODUCTION

Some documents we handle in everyday life can only be viewed in advanced electronic devices such as desktop computers or laptops. This is the case of PDF documents or slideshows. In some scenarios, the possibility of playing those contents on a set-top-box or any other screen-enabled embedded device would be of great interest.

2.

Uploads the file and the metadata to the server

3.

Performs all necessary tasks to convert the document to the desired format

4.

Carries out database updating to allow users to access the document in the output format

A. PDF conversion We use the ImageMagick tool [4]. The -density parameter defines the resolution at which the document is rendered, with a default value of 72 dpi (100%). At this density, a typical A4 page maps to a 595×842 pixel image. Note that -density is not equivalent to a simple bitmap rescaling (-geometry), since it exploits the vector properties of PDF documents.

We present an automated conversion system from PDF and PowerPoint to portable graphics, to allow the visualization of those commonly used formats on simple embedded multimedia devices like video players, digital photo frames or IP set-top boxes. These devices usually include a plain image viewer or a very limited web browser. Our conversion system is also of interest for institutional and educational IP TV environments with centralized multimedia servers.

Although 72 dpi may be enough for some documents, in other cases a higher resolution must be chosen, for instance if the document includes tiny fonts that would be otherwise illegible. The resulting image usually exceeds screen dimensions, and scrolling is necessary. This is irrelevant, since the orientation of PDF pages is usually vertical.

Regarding the final image format, JPEG is suitable when the original document includes true color images or photographs. However, we recommend PNG when possible, since it does not incur compression losses.

convert

There exist other tools, mainly desktop applications, to convert PDF and PPT files to images [1-3,7-9]. But they have not been conceived as part of an automated framework, and they not follow a submit-and-forget remote server-based approach. We do not impose any computational requirements for document conversion or playback at the client side.

B. PowerPoint conversion For this MS Office proprietary format we need a reliable free rendering tool, which should be adequate for an automated framework. A specially designed OpenOffice [5] macro performs image conversion from PPT and PPS documents.

II.

SYSTEM DESCRIPTION

Our document conversion system is a Linux-based tool that is part of a video on-demand educational platform. To upload a document to the system there is a PHP web script that performs the following operations: 1.

Presents a template to enter all the documentrelated info

We automatically obtain an image for every page in the document. For example, the ImageMagick command line -density

144

foundations.pdf

foun-%d.png

generates images foun-0.png, foun-1.png... To extract a single specific page from the document, it is possible to run convert -density 144 foundations.pdf [0] cover.png.

Since the process that invokes the macro is a PHP server daemon, it is necessary to create a virtual video buffer before launching OpenOffice. A bash script deals with this intermediate step and then calls OpenOffice with proper arguments. The basic script is the following: #!/bin/sh pid=`ps -eaf | grep Xvfb | grep :20` if [ ! $pid ]; then xauth add :20 . `/usr/bin/mcookie` > dev/null

978-1-4244-5176-0/10/$26.00 ©2010 IEEE

This full text paper was peer reviewed at the direction of IEEE Communications Society subject matter experts for publication in the IEEE CCNC 2010 proceedings

Xvfb :20 -screen 0 640x480x24 & sleep 5 fi /usr/bin/ooffice -invisible -norestore -display :20 "macro:///Standard.Module1.SplitSlides($1,$2)"

For example, the following command line generates a JPG file for every slide in the presentation:

Next, the users can click on the ‘play’ button to start viewing the document, as just another multimedia content. The arrow keys on the STB remote control allow to navigate and scroll across the different pages/slides (Fig. 3).

./splitslides.sh profits.pps jpg

The OO macro (SplitSlides) opens the original document and exports every page in it to the required format by means of a filter. It requires two parameters: document path+name and image output type. C. Demonstration layout For the tests, as visualization device, we used an Amino AmiNET110 IPTV set-top box [6], with an ANT Fresco web browser. The process to add special contents to our multimedia platform is quite simple. The first step is document upload. Fig. 1 shows a screenshot of the HTML template we fill. Figure 3. Playing the converted document on the STB screen

III.

CONCLUSIONS

We present an automated conversion system to adapt document formats to simple embedded devices. Unlike previous approaches, it does not impose any requirements for content conversion or playback at the client side. As future improvements, we plan to support new special formats, such as Macromedia Flash. Another interesting feature would be inserting delays between slides, and even exporting some audiovisual effects to enrich slideshows. REFERENCES

Figure 1. HTML input template

Once the document is in the server, the conversion procedure takes place. In a few seconds, the output can be accessed from the STB user interface, as shown in Fig. 2.

[1] [2] [3] [4] [5] [6] [7] [8] [9]

Figure 2. The converted output is available at the STB interface

PDF-Convert Inc, http://www.pdf-convert.com Universal Document Converter, http://www.print-driver.com Word Pdf Convert - PowerPoint/PPT to Image Jpg/Jpeg Bmp Tiff Png Converter, http://www.word-pdf-convert.com ImageMagick, http://www.imagemagick.org OpenOffice, http://www.openoffice.org Amino, http://www.aminocom.com PPT To Video Scout, http://www.bytescout.com/ppttovideoscout.html PPTmovie, http://pptmovie.uptodown.com/en/ Moyea PPT to DVD Burner, http://www.dvd-ppt-slideshow.com