Posts tagged ‘video’

Collection of hacks

Its been quite a while since I last posted anything.

That doesn’t mean that i haven’t been coding small hacks, just that i haven’t posted them. But now is probably a good time to show some of the stuff.

As the title suggest it has something to do with I have been using processing on and off for some time. Its is really nice when you want to make a quick hack, or as its called in processing a “sketch”.

In no particular order here is some of the fun stuff made using processing.

General remarks

The following sketches and their sourcecode have served as small hacks, hence don’t expect nice comments or optimal algorithms…


It is possible to remove the line from a picture representing the least amount of information. The algorithm evaluates every pixels “weight” as the absolute difference between the different color channels (r,g,b). And then finds the “lightest path” from the bottom to the top.

This means that “prominent features” won’t be removed or change size when shrinking the image. Here the definition of “prominent features” is high difference in colors between the neighboring pixels.

Have a look at shrinkImage

Room for optimizations :

Eventhough its quite quick at calculating the weights and finding the lightest path, it does so in every iteration. Letting it use a bit more memory and just recalculate the changes when removing a line should speed it up. I found a huge speedup when just having an array with the weights from the last and current line, when calculation the path, so not only would saving all weights require a bit more memory it would also slow down the first calculation. But I’m sure it would give a significant speed up in the next iterations, and a lot of +-1 frustrations ūüėČ


There a some quick getting to know processing hacks, this is one off the. helloFoo

One of the very cool things about processing is the ability to use openGL, so originally this sketch uses openGL. But applets and openGL isn’t exactly the best combination. It can be done, but since it doesn’t work for me (firefox, linux openJDK JRE) i just converted it to standard java graphics. And the effort required to do this, is remove an import and don’t say setup(400,400, OPENGL) but just setup(400,400). This is trivially true the other way around. If you want to use openGL its quite easy.

The sketch is just bouncing balls, when going away from openGL I reduced the size and number of balls, in order to get a decent animation speed.


Again used openGl originally FooIII

Some satellites rotating around some satellites rotating around some ….


yes sketches tend to have silly names : sndHello

From Clifford Pickovers  book : Computers, Pattern, Chaos, and Beauty Рgraphics from an unseen world (p 39 section 4.3 snowflakes from   sound)
Draw symmetrically and in “polar form” the¬†fft of the sound, hence creating snowflakes based on the sound.
Music by David Rovics
Choppy sound I had some problems with the sound when run as an applet. You might have better luck using the jar directly or by downloading the sourcecode and running it with processing


The former applet relied on an external library for the sound, ther are quite a few libraries available. I did use GSvideo to hook up my crappy webcam and do some video effects. I experimented with slit-scanning in different ways.Unfortunately this won’t run as an applet and it might only run on Linux.

By creating a cube of the images, where the z-axis represents time, its possible to play back different parts of the movie from different layers in time. Which makes for some quite interesting and dizzing effects.

For example a time buble where playback is delayed around a “bulge in the timespace continuum” :s (a video of some guy playing with it (timebuble1.avi) some sourcecode for a similar effect where the mouse pointer moves the buble (TimeCube.pde) another more “traditional slitscan” (CamWarpTime.pde) .

In general there is plenty of room to fiddle with the code, there a functions like selectSlice or initQueues where its decided how to slice time. its great fun to play with..

Flash development

A course Im taking requires that we use flash and we are left to using specific workstations at school or download a 30 day trial for the 6-7 week project. And well either way we are supposed to be using a proprietary piece of software from Adobe.

The first flash assignment were to create a picture slide show, with captions and a soundtrack. Using the Adobe flash gui its very easy, drag and drop “programming”.

But as Richard Stallman says “its not a matter of convenience, but of ethics”. So I went looking for replacements. In another course I had no problems using octave instead of matlab, so should this be any different? Yes, unfortunately it seems that its very difficult to get the needed features in free software, well at least in the given timeframe.

HaXe is able to compile to swf, as well as doing a lot of other nifty stuff. I just learnt about it recently from this video.

I didn’t manage to make the entire assignment, (yet?) in haxe, but i did make this :
flash presentation(5MB+)


I did manage to add sound and captions.

So how did I do it?

Well first of all i installed haxe and swfmill. Haxe is able to use the actionsscript api and swfmill can create resources so your are able to refference them in you haxe code.Here is the recipe i used to create this slideshow.

1. create a xml file for swfmill, in order to create a resources for the haxe code.This i something like

 <movie width="480" height="480" framerate="25">
      <library><clip id="img1" import="library/newton001Slide_.png"/>

unfortunately swfmill isn’t able to add sound to a library, so that had to be loaded directly from a file. I had some trouble getting it to function on the server but i think that adding “-D network-sandbox” to the haxe compilation might have done something. ???

2. run swfmill, thats swfmill simple slides.xml slides.swf

now i had linkage names for the image files, and could add them to the movieClip.

3. Create file SlideShow.hx

The main part. The basic haxe syntax is pretty straightforward, but since it uses the actionscript api it were mostly a question of getting a hang of actionscript. I did however strugle a bit with making a anonymous function, for the sounds onLoad. I used “static inline function sndStart(succes){…}” , its a wee bit diffrent than what i would do in java. but it works.

3. compile.

make a “make file” for haxe, compile.hxml

-swf test.swf
-main SlideShow
-swf-lib slides.swf
-swf-header 480:480:25:FFFFFF
-D network-sandbox

The last part -D is a conditional flag and as far as i can tell it shouldn’t do anything, but a saw it in Fmp3PlayerHx and when i added it the sound seemed to work from the server, using a URL :s :s

4. run haxe compile.hxml

5. display the pretty result. (try not to go crazy when wordpress decides to help you format the html code….), at first i tried embedding the flash in this post, but wordpress kept on changing the code, apparently if you add code and have newlines between the tags it throws in a couple og <p> tags …..

Now its on a separate page, then you don’t have to download the 5 mb flash file just to view the page, and I can use wordpress with out getting too frustrated.

sourcecode slideShow.hx

The music is “the free software song” this version is by Jono Bacon , and I personally prefer it to the version by Richard Stallman

Sound Sequencing Mouse

I saw this cool sound sequencer ( arduino punk console ). I don’t much about sound and that kind of stuff, but i thought it was quite nifty. And I had just gotten a ps2-mouse to work with the arduino. And hmmm, I had to use it for something. So why not try to make a sound sequencer with it ?

So I started hacking away. Unfortunately I don’t have any nice video or sound clip, but then again its more like a noisemaker and its just a mess of wires. I’ll try to get something up soon.

But it does work, you have to take my word for it or download the sourcecode and wire up your arduino and try it out.

How does it work ?

There a two modes of operation “play mode” or “sequencing mode”, and it shift between modes by clicking the middelbutton (mousewheel button) and it starts out in sequence mode.

sequencing mode

  • moving the mouse changes the frequency of the sound. It’s very simple the more you move, the more it changes (just by (X + Y) *magic_number)
  • pressing the right mouse button reduces the duration of the sound
  • pressing the left mouse button increases the duration
  • turning the mousewheel selects a tone in the sequence, either an existing or adds a new one to the sequence.

play mode

  • it plays the sequence of tones you’ve recorded.
  • the mouse wheel changes the playback speed.

So it keeps track of both a duration and a frequency, it uses a queue and its possible to add sounds to both ends. I haven’t yet hit a maximum but since its in a int array my guess is that it should be able to hold a lot 100 or 1000 of tones. And it should be possible to do some bytepacking to reduce the memory requirements, but since you have to enter each sound manually and there are no persistent storage you really don’t need that to hold a lot of tones.

Sound Sequencing Mouse sourcecode