Archives for January 2017

I have a dream

This is too long for a tweet or fb post so...

I like big screen TV displays - in this a case its a raspberry Pi in my sailing club running Screenly, since, underneath its linux anything it can't do I probably can using its local install of apache/php/mysql/SQlite (apt-get install [whatever]. Current fun stuff I've done with it:

• Showing people how to make a PowerPoint show (PowerPoint "export" uses the right codecs for Screenly free, fantastically simple solution) - rating: Simples!
• Go on line once a day trawl through the Top Yacht Results Site, find DSC, then identify series, fleets, and races. Track them in a database, then Download the HTML of the race, rewire it in bigger fonts etc. If too long scroll slowly down, show only recent races less than X days old. - rating: Headache
• Display a map of the current progress of long distance yacht races eg Darwin Ambon - rating: Sounds Simple. Isn't.

The last is a dream of mine. Sounds simple but:

• I like my sailing club, they're luddites, the have no idea what internet plan they have (Australia hasn't discovered unlimited broadband yet) but I don't want to blow their cap, or bankrupt them.
• The trackers are usually interactive I.E. you have a hodgepodge of of zoom and click controls all over them. This is no use on a Digital Sign.

Last year's fudge'o'matic worked something like this, Laptop in office running Firefox (lower security) and Auto Hotkey and a screenshot plugin. Methodology was every hours or so auto hotkey sent f5, waited a few minutes then sent shortcut key to screenshot app, saves it in a folder that's inside a web-server. Then a PHP scripts retrieves the directory listing off the web server, sorts by file timestamp and displays the latest screen shot on the Telly. DISABLE widows update, power management, any auto updater with a prompt. Hope it works. It sort of did. Mostly it did. Horrible though it was.

• Advantages - screenshot is loaded every 5 minutes as screenly cycles through its other stuff, but this local, no Internet required screenshot loaded every hour.
• Disadvantages
  • Every little bloomin annoying dialog box on widows will break it.
  • If it goes slow you get a screenshot of a 404
  • If it gets out of fullscreen it gets a window.
  • If firefox opens a tab suggesting you update (this actually happened) it displays on the telly.
  • If someone were to get bored and open the laptop and see what it was doing there, and say browse porn in firefox.....*shivers* the horror.

Anyway it worked, mostly, and because the tracker they used was so basic that it could be screenshotted.

This year they are going for Yellow Brick trackers again. This is the gold standard of trackers. Screen shot of trackers in not going to cut it. Website of YB trackers is detailed has hell, covered in interactive controls, interactive, group able rewindable replayable. in short unsuited to TV screen automation.However there is an API with an xml feed. So lets break down the problem now, while I have time to work on it:

1. One retrieve the XML file of latest positions
2. Store positions.
3. Create a leader-board (yay I love the trigonometry of spherical triangles in PHP) but I have done it before.
4. Display those positions on a map - without raping the clubs bandwidth.

I just succeeded in 1 and I think 2. Need to wait for a transatlantic rowing race to paddle further to make sure it can detect duplicates and update db. Row you b******s! I've done 3 before plus the Darwin - Ambon is pretty much straight north so if necessary I can cheat and assume difference in latitude between boat an Amahusu = distance to finish in nautical miles.

Four. Four is going to be a bugger - I can display boats, and tracks on Google Maps no problem, control the zoom and so on, BUT its likely to reload every x minutes and rape the bandwidth...... This years fudge may be a caching proxy...

I'm making a TV display, for hourly type updates, it doesn't have to be real-time or as accurate to the meter but it would be nice....