‘Animals’ is currently a very short flashcard set. The issue of image copyright is bothering me. I used WikiMedia Commons for the images in these flashcards, but it required a bit of brute-force searching to find images that were totally unencumbered by copyright. Most of the images in WikiMedia Commons seems to be under one of the Gnu licences or one of the Creative Commons licences. Wossis.com currently has no means of recording copyright information with the flashcard images, so I feel as though I should only use ‘totally free images’ (with one very obvious exception!).
The more I think about the copyright issue on wossis.com, the more I think ‘public domain’ is the way to go. 200×200 pixels is a fairly restrictive format for images – perhaps contributors to wossis.com will be happy to ‘let go’ of such small images? I must get round to making a page on wossis.com that clarifies the copyright position of images uploaded for cards. One day!
It required a bit more work than I was expecting, but wossis.com now has a shiny new Atom feed for updated cardsets. Atom is a format and protocol for providing news (the ‘feed’) about a website. You may have seen the little orange ‘ping’ icon on nearly every blog or news site you’ve ever visited. That’s an Atom or RSS feed.
I’m not going to include the little icon in any of the pages at wossis.com just yet. You can make a feed available from a webpage so that a sufficiently magical browser can discover it itself, and make its presence know to you. All you need to do is to include a link element like this one (taken from wossis.com’s homepage):
and your browser will let you know in its own special way that a feed is available from the site.
Feed Icon in the Firefox URL bar
Now when you click on the icon you should be offered the opportunity to ’subscribe’. Don’t worry – Site Feeds are free (usually)! Subscribing to the feed usually means that you’ll have an easy way of keeping up to date with changes on the site you’re subscribing to. If you subscribe to the cardset updates feed from wossis.com, you’ll be able to see which are the most recently created and updated cardsets. In Firefox you get this neat popup menu:
This isn’t the most exciting of flashcard sets ever! I wanted something to test a lot of work I’d done behind the scenes with Spinneret (the webserver that wossis.com is built on). It was a good test – it broke it! There was some horrendous code in Spinneret that received requests from browsers and broke them down into header fields and form data / posted files. That’s largely re-written now, and seems to be working perfectly when I uploaded the 40-card HTTP Status Codes flashcard set.
If you’re not familiar with HTTP Status Codes, they’re the very first part of the reply from a webserver when your browser makes a request. You won’t know 200 (OK), that’s what the webserver sends whenever it has what you’ve asked it for! You’ll almost certainly know 404 (Not Found) – you see that at some sites when you ask them for something it doesn’t have, perhaps because of a bad URL or the site provided a page or image once, but no longer does. Some websites occasionally break down while you’re using them, and give you a 500 (Internal Server Error).
I’m struggling to think of any more examples! A lot of status codes are invisible because they’re part of a conversation between your browser and the server that you really don’t need to know about. What status codes have you seen from websites?
It was only going to be a partial eclipse, but even so, I was looking forward to capturing it for my blog. Before you read any further, I should add the video here. Don’t bother watching it, unless you really want to feel as I felt today. It was cloudy. For the whole duration. Here’s the video:
It’s quite nice to see the clouds roiling above my house. Or is it?
USB Camera Obscura
The bit where you can clearly see two layers moving in different directions isn’t bad. If it looks like poor quality, it has been reduced from 640×480 to 320×240 prior to uploading to YouTube, and it was captured by my USB Camera Obscura! Here it is, sitting outside my house today.
The plastic table and chairs came in very handy! My Dell Mini9 was on one (covered in rubbish most of the day – I was worried someone would see it). The table served as a sun-shade to allow me to see the screen (almost impossible otherwise). The other chair was my ‘observatory’.
The cardboard box is the camera obscura. I didn’t actually test whether pointing the webcam directly at the sun would work. The way I see it is that if it didn’t work, there’s a slim chance I’d destroy my webcam, so I played it safe and made the camera obscura. It’s really just a box with a hole in. The image of the sky is formed on the side of the box facing my PC. The hole is facing the sky. I put a single sheet of white paper on the image side of the box to improve contrast. The webcam is rather clumsily taped to the lid of the box at the same end as the hole, but pointing towards the other end (where the image is).
If it’s not clear what’s going on – the video is of the image projected through a small hole in one end of the cardboard box onto a sheet of white paper at the other end – inside the box. The webcam is also inside the box. The dark edges are not the walls and roof of my compound – they’re the sides of the cardboard box, seen from inside. The webcam doesn’t ‘line up’ with the sheet of white paper because I only found out about the eclipse an hour or so before it was due to start! Everything was rushed!
Then all I did was run the magic mencoder command line:
That tells mencoder (part of MPlayer) to use the second webcam (the first is built into the lid in my Mini9) and create an AVI movie with no sound and 1 frame per second. The low frame rate is still much higher than needed for sky-watching, but was a compromise between not wanting to miss anything, and not filling up the tiny flash drive in the Mini 9. I think I ended up recording just over an hour of video, occupying nearly 2GB on the PC.
And then it was cloudy all afternoon ~:( and now I’m really, really disappointed! Never mind, it was good to go through the whole procedure. The camera obscura seems to work a treat. I think the Logitech webcam I’m using may not be the most sensitive in the world. It’s really hard to tell – maybe I should build in a light-proof eye-hole so I can check in future! There was a bit of light leaking in. You can see in the picture where I’ve tried putting black fabric tape over the corners of the box to cover up the holes. There’s a bit of an orange blur over the video: that’s light leaking in.
Just one last thing: the 1frame-per-second video is very annoying to replay! I changed it into a 20fps video, with this command line:
The filmdint filter drops 24 out of 25 frames (so I end up with one frame for 25 seconds of ‘action’). I keep staring at this command line and failing to understand how I end up with just over 1 minute of video from well over an hour’s worth of data. It’s very late now, and I’m a bit sad about the result of my ‘hard work’ today, so I’ll leave that last bit as an exercise for the reader.
Many thanks to Chew Hong Liang, who helped me to test the new ‘Copy cardset’ feature and provided the captions and audio clips for the flashcards. Quite a lot more people were involved in choosing the name for the cardset! 五官 – ‘wǔguān’ in Pinyin was suggested as the best title.
My Chinese is lousy, so when I directly translated ’simple words for parts of the head’ into Chinese, everybody just lifted the corner of their lip, or one eyebrow! I see that 五官 is translated as “five sense organs” at one website. I’d be interested to know what anybody else thinks.
Wossis isn’t intended to be a replica of Wikipedia. It seems to me that there could be many, many different sets of flashcards for 五官, differing in picture design, in explanatory text, or pronunciation of the words. You can’t normally change another user’s flashcards (though I have just also added a permissions-granting system), to prevent vandalism of your (or your favourite) flashcards. To make it a bit easier to contribute your own version of existing cardsets, I’ve just added a ‘Copy’ facility that will copy anybody’s cardset as your own.
I imagine one day there’ll be a need for a facility to remove copies that don’t add anything to the originals, but are just attempts to pass off someone else’s work as the copier’s. I’m not sure at this point how that’ll work. Drop me a postcard with your suggestions!
