[rawles.net]

edit-tf: an in-browser editor for teletext frames

In 2014 I was working on a teletext project with Dan Farrimond to celebrate forty years of the medium. Then, designers would prepare frames using aging professional and proprietary editors, convert them to a graphic format like PNG, and upload them to the web. Dan felt that although having more and more of this kind of work online was great, what would really help catalyse an online teletext scene would be to have an easy means for people to edit their own frames, perhaps to contribute to amateur teletext services. In response, I wrote edit-tf, which allowed anyone to open up a page in their web browser and do just that, providing they could get their head around control codes and the like. edit-tf was designed to be free and available to everyone, and was licensed from the outset under the GPL v3.

At the time, a novel feature of edit-tf was that the data for the frame was encoded in the page's URL, rather than being on a backend or cloud server. This opened up possibilities for easier frame creation. It meant that the user could bookmark the page, saving the frame to work on later. The user could link to the page on a website so that visitors could open up an editor with the frame ready to improve or use in their own work. Similarly, users could collaborate on a frame by sending the URL via email or instant messengers. Because the data is stored in the URL fragment identifier, the part of the URL after the # symbol, it doesn't show up in my web server logs and the pages are private to the user (at least from me).

Since 2014, the amateur teletext scene has grown and a lot of work has been done on a wide variety of teletext projects, even on new editing tools. In particular, Alistair Cree has produced a in-browser teletext editor, the ZXNet editor. It is more full-featured, more correct, and more regularly maintained than edit-tf. I'd now recommend it to new would-be teletext creators.

However, you can try edit.tf out online. GitHub hosts the source code and documentation. This page will serve as an occasional source of edit-tf news, including those times when I open up my laptop and have a go at solving one of the outstanding bugs or enchancements. Contributions and improvements are still, of course, very welcome.

Stay blocky!


Another benefit of having the data in the URL is that, to some extent at least, the web will have scattered across it teletext frames in the form of edit.tf (and zxnet.co.uk) URLs. These URLs are trivial to identify and can be converted easily into frames.

The Google search operator site: seems to promise to return all URLs in Google's index with a given site or domain, but in our case, this doesn't work, perhaps because of the use of the URL fragment identifier (the part of the URL after the # symbol). This would make sense, since the conventional use of the URL fragment identifier is to identify a part of a document. Neither DuckDuckGo nor Bing do this either.

A web archivist could run a web crawler or network of web crawlers to wander over the web, looking for these URLs, and harvesting any that it sees. Though the web is big, perhaps teletext frames can be found on a small and predictable part of it, and a heuristic could guide the crawler. What remains of the HTTP referer field in edit-tf's server logs after the fragment identifier is removed, and where it is even passed by the browser at all (because of privacy and security threats), could nevertheless be used in seeding the crawler or informing such a heuristic.

Half a dozen new frames from Dogetext in the examples archive. Later in the day, one more. A vintage frame from TVE was reconstructed by the same author, with a subtle hold graphics trick.