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There was a video the other day which I posted about where the video footage was all highly pixelised into circles of varying sizes and colours, and I reckoned I could produce a similar effect by either resizing the stream down so it’s really blocky then scaling it back up or reading all the pixels in a block, averaging the colour and then drawing blocks of that averaged colour.

Well, I had an hour or so today to do a bit of “me-coding”, and in the end I took the second option.

The pixelisation works on the live stream, and you can drag the slider around to switch through from 1 division (i.e. the entire window is one block of solid colour) to 160 divisions.

I’ll bring the values into OpenGL and see what I can do with points and the like when I have another hour or two spare over the coming few days – fun stuff =D

Source code after the jump for those interested…

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I’ve started learning OpenCV, the open-source computer vision library, and I’ve got to say – it’s absolutely brilliant. In the below screenshot I’m just running the canny edge detection filter on the live stream and outputting it in a window with some sliders which link to the edge detection parameters, and the entire thing from initialising the web cam, to displaying the frames and performing all the filtering is a little over 100 lines of code… Amazing!

It’s when I start asking OpenCV to do things that it currently doesn’t do that I’m going to start screaming, and I read that optical flow analysis has stolen the youth of many a Ph.D student… But how awesome will it be if I can make a really robust gesture recognition system and tie it into OpenGL? I guess there’s only one way to find out…

Full source code after the jump for those interested (although please don’t ask me how to build/install OpenCV and link the libraries into the project – it’ll vary depending on your system and build tools of choice).

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I found these instructions on the PulseAudio Wiki a long while back, but they still work (circa Ubuntu 10.10) and are super useful to record streams/record the audio from videos (i.e. YouTube), so I thought I’d put this out here under a different heading to help people find the info…

1. Install PulseAudio Volume Control by running the following in the Terminal:

   sudo apt-get install pavucontrol

2. Fire up Audacity and:
   – Go to Preferences by pressing Ctrl+P (or select “Edit” -> “Preferences…” from the drop-down menu).
   – Click the “Devices” .
   – Change the Playback device to “pulse”.
   – Change the Recording device to “pulse”.
   
   
3. Open PulseAudio Volume Control (“Applications” -> “Sound & Video” -> “PulseAudio Volume Control”) and leave it open.
   The first time you use a recording program you need to to edit the recording settings of PulseAudio Volume Control. It should remember your settings after rebooting.
   
   
4. Open Audacity and hit the “Record” button.
   
   
5. While Audacity is recording, open PulseAudio Volume Control and select the “Recording” tab. It will show “Alsa plug-in Audacity. Alsa capture from” and a combo-box. Choose the “Monitor of internal audio…” if you use an internal sound card.

Note: You need to select another monitor if you use any playback device other than an internal sound card. For example, when I play sound with Microsoft LifeChat headphones connected to my computer via USB, I select the “Monitor of Microsoft LifeChat Analogue Stereo” to capture from it with Alsa.

6. Check Audacity, it should be recording now.

Sling a note in the comments if you’re having any difficulty enabling recording of the “stereo-mix” output – not that you should come up against any problems, but I’m happy to work on clarifying the wording if it’s necessary…

Cheers!

Apparently, due to freak conditions the Gulf Stream has left the UK for Greenland it’s winter in the UK – and this is the result! (Gulf Stream myth debunking here).

Beautiful, yet frickn’ freezing!

There’s a high of 32C in my part of Oz today – and can’t say I really miss the cold that much at all