CebraText Quick Tutorial, Version 1.2

by Paul B. Davis / Lektrolab

email: paul@lektrolab.com

 

Updates:

ADDED Section 2.6 Extra Design Tips

ADDED Section 3.3 Microtel Pages

UPDATED Sections 1.2, 3.1

EDITED various typos

 

CONTENTS:

 

1. INTRODUCTION

1.1 Purpose

1.2 Microtel Project Credits

 

2. DESIGNING PAGES WITH CEBRATEXT 1.1

2.1 The Teletext format

2.2 Page Layout

2.3 Control Characters

2.4 CebraText modes

2.4.1. Text Input Mode

2.4.2. Graphic Input mode

2.5 Importing Bitmap Images

2.6 Extra Design Tips

 

3. SUBMITTING YOUR PAGES

3.1 Saving

3.2 Submitting

3.3 Microtel Pages

3.4 Other Info

 

1. INTRODUCTION

 

1.1 Purpose:

 

CebraText is a freely available teletext editor for the Windows operating system. It is, in fact, the only fully-functioning free teletext editor we've found for Windows - all the others use dongles and are save-disabled.

 

The purpose of this tutorial is to introduce CebraText's use and functionality so that anyone who wants can design pages for the Microtel - a teletext TV station running on NOS [Dutch public television] during the 35th International Rotterdam Film Festival [Jan 26 - Feb 5, 2006].

 

1.2 Microtel Project Credits:

 

Microtel is a project run by Lektrolab [Emma Davidson & myself] and is part of the VBI section of the "Satellite of Love" exhibition and laboratory. VBI is produced by ambientTV.net and Satellite of Love [Microtel included] will be held at the Witte de With center for contemporary art in Rotterdam.

 

http://www.ambienttv.net for more infos on VBI.

http://filmfestivalrotterdam.com for more infos on the Rotterdam Film Festival

http://www.wdw.nl for more info on the Witte de With center

 

Just had to make sure everyone was mentioned - you know how it is.

 

2. DESIGNING PAGES WITH CEBRATEXT 1.1

 

2.1 The Teletext format

 

A teletext page has 24 rows and 40 columns. You can think of a teletext page as a 24 x 40 grid where each space on the grid can contain a character of text [the font is mono-spaced], a graphic character, or "control character" - a special character that changes the color of the text, graphics or background. However, the top row is reserved for system information and isn't editable with CebraText and the left-hand column is used to hold color information. At the moment I'm not sure if the left-hand column displays on TV's so it's best not to use it for anything other than control characters [see section 2.3]. In effect, then, while the page is 24 x 40 in size, think of it as having an editable area of 23 x 39 with the top row off-limits and the far left-hand column only for control characters.

 

2.2 Page Layout

 

Each row defaults with white text on a black background. For every change in color [text or background] or other attributes [flashing, etc] you must insert one or more control characters. The change will affect the rest of the row unless modified by a subsequent control character on the same row. Each control character takes up one character position and will display as a blank space on the TV screen. I find it helpful to make the control characters visible by checking "Show Controls" under the View menu.

 

2.3 Control Characters

 

The main control characters are Change Graphic Color [GR], Change Text (alpha) Color [AL] and Change Background Color [NB]. Graphic color and text color control characters can be set on their own at any time and actually specify the color to change to, the background color characters is just a general "set background" character and relies on a previous graphic or text color character for the color information.

 

Examples:

[Graphic Color BLUE] + [Change Background] + [Text color YELLOW] = Yellow text on a blue background for the rest of the row

 

[Text Color RED] + [Change Background] + [Text color WHITE] = White text on a red background for the rest of the row

 

As you can see, text and graphics colors are set with just one character while it takes a combination of two characters to change a background color. The one exception to this is a special Change Background BLACK character that will change the background color from anything to black.

 

2.4 CebraText modes

 

CebraText has two modes, text input and graphic input. While text and graphic characters are pretty much the same, and you can input graphic characters in text input mode, Cebra also has a special graphic input mode so you can draw lines and shapes with the mouse and the correct graphic characters are applied. Both are available under the "Tools" menu: "Standard Text" is text input and "Graphics Select" is graphic input.

 

2.4.1. Text Input Mode

 

Text input mode is the initial mode when you make a new teletext page. Type on the keyboard for text & number input and change text color by clicking with the mouse on any of the colored "TXT" buttons in the floating toolbar. You can use the arrow keys to move the cursor around the page. If you're in graphic mode you can get back to text mode by clicking "Standard Text" under the "Tools" menu or the "T" text button in the top button menu.

 

To place graphics while in text mode, click on any of the colored graphic buttons in the floating toolbar - they look like X's missing the bottom left bit and are right under the colored "TXT" buttons. What they do is insert the various Graphic Color control characters into your teletext page, and while you are still in the "Standard Text" editing mode all the characters you type with the keyboard are now graphic shapes in the color of the box you clicked. Teletext graphics divide each cursor space into six "pixels" - three rows of 2 squares:

 

XX

XX <-- diagram of cursor space as a graphic

XX

 

The keys on the keyboard now give you different combinations of this graphic instead of numbers and letters. To get back to text input click one of the colored "TXT" boxes again.

 

2.4.2. Graphic Input mode

 

Graphic input mode is for drawing shapes using the mouse which are converted to graphic characters. You can access it by clicking "Graphics Select" under the "Tool" menu, or by clicking on a number of the graphic tool buttons [line, rectangle, filled rectangle] in the top button menu.

 

In order for graphic mode to work your teletext page must already have some rows set with Graphic Color control characters - only rows that have those control characters set in them can be used in CebraText's graphic input mode. Once you have placed the control characters in the rows, let's say you've put a Graphic Color control character at the start of each row for the top six rows, you can then select one of the graphic tool buttons and start drawing in those rows. CebraText will automatically input the correct graphic characters down to pixel resolution to create the shape.

 

2.5 Importing Bitmap Images

 

CebraText can import/convert bitmap images to teletext "pixels", although very simply. It helps to do a bit of editing of with your bitmaps beforehand to ensure the highest quality teletext output.

 

In your preferred bitmap editor, reduce the size of the image as much as possible [smaller than 100x100 is suggested], make it a black & white image only [2 color bitmap], and invert the colors [black turns to white, white turns to black]. Now copy your image to the clipboard.

 

In CebraText, open a new page and insert Graphic Color control characters at the start of every row for the whole page. Now switch to Graphic Input mode [see Section 2.5.2]. Once in Graphic Input mode, use the mouse to highlight the entire area of the page that you want your bitmap pasted into [CebraText will scale the bitmap to fit]. For the highest quality image select the whole page. Now click "Paste" from the "Edit" menu and your bitmap stored in the clipboard will be pasted into the teletext page as graphic pixels.

 

2.6 Extra Design Tips

 

Wendy @ NOS suggests not using blue text on a black background as it is difficult for people to see. Also, Ronald @ NOS says using black text on any background is suspect - the original teletext specification did not allocate "alpha black" [later one's did] so some tv's may not display black text at all. The CebraText "default" change background color is white [if you insert a "change background" character without first inserting a color character it will make a white background], and we don't know if this actually works on tv's so for the moment you should probably not use it and always insert the white color character first.

 

3. SUBMITTING YOUR PAGES

 

3.1 Saving

 

When you have designed your teletext you need to save it. The CebraText "Save As" menu gives three options - CebraText Format (*.TTX), 971 Format (*.TTV) and 1091 Format (*.TTV). For your own use you may use any of these formats, although the CebraText format is probably best. For submitting your pages to Lektrolab for the Microtel Teletext station you need to save your pages in 971 Format and email us the *.TTV file.

 

NOS has decided to limit the Microtel broadcast to single pages, so any animations [pages with subpages] submitted to us cannot be displayed - although we may use them in other ways [on the website, DVD, etc.]. If you really want to make a slow animation you can submit it as individual pages and we will try to broadcast them in sequence but we cannot guarantee it - also keep in mind that each numbered page that NOS has given us is limited to 5 teletext pages per day [see Section 3.3].

 

3.2 Submitting

 

Once you have saved your page in 971 Format, email the *.TTV file to vbi_microtel@lektrolab.com

 

Again, Microtel runs from January 26 - Feb 5. Anything you can send us before January 26 is best but you can also email us pages up until the end of the festival. FINAL DEADLINE FOR SUBMISSIONS IS FEB 4.

 

3.3 Microtel Pages

 

The NOS pages that have been allocated to Microtel are 450 through 455 and Microtel will start broadcasting them on Thursday 26 Jan 2006. We have arranged the pages in this way:

450 - Project info and credits

451 - NeverEnding Story [Emma & Paul's teletext soap opera]

452 - Public Art Submissions

453 - Micromusic Submissions

454 - Public Art Submissions

455 - Microtel Studio Blog

 

On each numbered page, 5 teletext pages will be displayed each day, for one day, and then replaced with 5 new pages the next day. You can view the pages on channels Nederlands 1, 2 or 3 on your TV [in the Netherlands, obviously] or on the NOS website: http://teletekst.nos.nl

 

3.4 Other Info

 

Please keep checking http://projects.lektrolab.com/microtel for up to date info about the Microtel project. For help and questions you can also use the vbi_microtel@lektrolab.com address.

 

-- January 25, 2006