Teletext Meddler SE


Teletext Meddler is a program to assist with the cleaning and restoration of teletext recoveries.


Known Bugs and Limitations
Getting Started
File Opening
File Saving
Page Editing
Page Clip
Status Bar
Control Flags & Language
FastText Editor
Keyboard Shortcuts
Miscellaneous Functions
Example Workflow
Questions & Remarks

Known Bugs and Limitations

Getting Started

To run the program, you will need a computer running Microsoft Windows 7 or above, with the .NET Framework 4.8 installed.

Unpack the archive anywhere you want. Run the program TeletextMeddler.exe.

Teletext Meddler SE annotated interface.


There are several ways to step through the pages. The simplest is via the address bar at the top. The first two boxes combined represent the page number, e.g. 1 & 00 = 100. The third box is for the subpage, usually used for long articles. The final box is the instance. The first occurrence of a page & subpage combination is the first instance. Subsequent repeats add more instances.

You can also use the Page Up & Page Down keys on the keyboard. These will step through subpages, but not instances.

The fastest way is using the mouse. Scroll up to go back, and down to go forward. This also steps through subpages only. (Depending on how your computer is configured, you might have to click on the page viewer first.)

File Opening

All the conventional ways work (File menu, file association, etc). It is possible to choose and load multiple files in a session to create a larger, single file.

This allows you to load recordings split into chunks. I tend to record in 15 minute blocks. Ensure the blocks are loaded in the right order (10:15 before 10:30, etc).

File Saving

When saving, all the pages will be written to the first file opened. Its name is shown on the title bar.

Your pages will be written out in sequential order, from 100 to 8FF. Lines are also saved sequentially, i.e. not interlaced in a broadcast-like manner.

Page Editing

When you click on the page, the region underneath the mouse pointer is highlighted by a small, white square. This is the cursor.

You can move the cursor around the page with the arrow keys, pointing and clicking the mouse, and by typing corrections and such - much like a word processor. It will stay in position between page changes. Press ESC to hide the cursor.

Changes can also be made using the right click menu. A weighted list of possible alternative bytes based on common errors will appear. Another way is with manual set. Enter the hexadecimal value in the box on the right. A history of 3 recently entered values is available for quick use.


The clipboard does not work quite like in other programs: it only deals in whole lines. You can only paste lines copied from Teletext Meddler. To increase confusion, there are two clipboards: an internal clipboard, and the normal Windows clipboard.

The internal board is split into 25 lines. Each line has its own memory to copy or paste from. You can copy any line by selecting it with the cursor, and going to Edit - Copy Selected. Pasting is also done with that menu.

The internal clipboard is best used for repeating areas such as page headers.

The Windows board is less restrictive, but only holds one line. You can copy any line and paste it to any other line, even between separately loaded copies of Teletext Meddler.

You might be familiar with these keys; keyboard shortcuts for copy and paste. They are used heavily in Teletext Meddler, but the action taken depends on a setting.

Press F12 to change this setting. There are four possible states: Windows clipboard, Internal clipboard, FastText data and Control Flags.

Example: If you set the state to FastText data, you can use CTRL-C to copy the FastText links from one page and CTRL-V to paste them into other pages.

Page Clip

The page clip is a temporary storage area for page collections. You can add any number of pages to the clip and save them all together into one file. This is useful if you need to extract a set of specific pages from a raw capture.

Use the Page menu to access the clip functions.

Status Bar

The bar at the bottom tells you how many pages are loaded, the location of the mouse or cursor, and information about CRCs. Debug messages can also appear in the centre.


Some broadcasters transmit CRCs for their pages, and some don't (you will see 0000, 2020, and 8080 amongst others in those cases). For those that do, you can be confident with the integrity of the restoration if the transmitted value matches the page's value. The status bar will go green.

There is a caveat. Sometimes the CRC itself is corrupted, in which case a perfectly valid page will not go green. There are a couple of helper functions in Teletext Meddler that might help.

Teletext Meddler corner screenshot.

The three possible CRC states.

CRC List
Most raw deconvolves contain multiple copies of the same page instance. Each copy ought to have the same CRC, unless the page was subsequently updated. Meddler can extract all permutations of the CRC for every page and compare them. If the page doesn't have a valid CRC (according to the broadcast), but does have one in the list, the status bar will go dark orange. You can view the list by right clicking the page CRC.

Bit Flips
Often when a page is perfect but the CRC isn't matching, its due to one or two bit flip errors. The difference between 7 and F is only 1 bit. Meddler will forgive a maximum of 4 flipped bits, one for each "character" of the CRC. e.g. 123F would be forgiven against 023E. The status bar will go gold in these cases. Warning: false positives are very possible. Use your intuition to decide if there's an error on the page or an error in the CRC.

If the status bar isn't green but should be, click on the calculated CRC. The page CRC will be replaced with it, and therefore become green.

Control Flags & Language

These do not affect the display in Meddler (nor does hide row 24), but might in other programs. Tick or clear as appropriate.

Changing the country will modify the character set used to display the page.

FastText Editor

The FastText editor interface.

With this you can edit the six links on the page shown underneath the viewer. You can also change their designation code and link control bytes.

Keyboard Shortcuts

F1-F3   First/second/third option in the right click menu.
F4   Last option in the right click menu.
F5   Refresh
F6   Set page CRC to the calculated CRC.
F12   Change clipboard behaviour when using CTRL keys.
CTRL- +/-   Increase or decrease value of selected character by 1.
CTRL-S   Save
CTRL-O   Open
CTRL-T   Toggle display of graphical symbols (i.e. text only).
CTRL-B   Brute force CRC.
CTRL-N   Insert a new, blank page. You will be prompted for an address.
ESC   Hide the cursor.

Miscellaneous Functions

Control Characters
Show or hide the (normally hidden) control characters.

Black & White aka X-Ray
Turns off page colouring instructions.

Show or hide hidden areas on pages.

Double Height
Allows or ignores double height character instructions.

Parity Map
Underline all characters on the page. Green = valid parity, red = invalid parity. Note: Pretty much useless in most cases.

Brute Force CRC
Attempts to guess where a possible erroneous character is on the page. It only goes one character deep and only makes suggestions. Use sparingly - the program might seem to freeze.

Renumber Page
Change the address of the current page instance.

Line Precedence
When loading a teletext stream; if two or more lines compete for the same location on the same page instance, decide which one is used. See example file.

Recalculate Parity
Fix all parity errors in saved files. Note: this means the parity map will only show green upon reloading.

Discard Empty
Do not save any lines that only contain spaces.

Debug Mode
Changes the behaviour of some program functions, and makes it chattier.

Example Workflow

Questions & Remarks

The font is ugly.
Once you've edited the file, you can always load the results in another program with a more authentic font.

It's buggy.
Sorry about that. You can tell me about any bugs you find - include all error messages, how it was done, etc.

The address bar flickers.
I know, it sucks. It wasn't designed for so many quick changes. Fortunately, the content is the focus.

I've made a mistake. Can I undo?
No, there's no undo system. If you haven't saved, you can open the file in a second copy of Teletext Meddler and copy content back across.