Dec 27

TI Stellaris and 28byj-48

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I had 2 impulsive buying of paperweights collecting dust – TI Stellaris Launchpad and 28byj-48.

The reason for purchase in both cases was dirt-cheap price.

Well, Stellaris is no longer a paperweight – thanks to the guys who wrote Energia

I plug thing together and it did not work. I swapped wires to inputs 1 and 2 and it started spinning. Why is that? I’m not sure, but I have noticed that LEDs on the control board fire in the wrong order, and I foxed it with swapping wires. Now it spins OK.

stellaris

You can see 3 LED ON – it is side effect of digital camera long exposure time. Only 1 or 2 LEDs are ON at a time.

How I’m going to use it? I have no idea. Perhaps, it will go to back to the shelve.

See source code after the break. I did not write it – I found it on the internet and tweaked a bit.

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Nov 06

Kinect Face Tracking

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It is easy to plug a Kinect to PC – all you need is a cheap adapter. Then you can control something with it.
kinect

Watch the video:
Kinect-to-Arduino-to-Pan-and-tilt

It takes a little bit of programming, but that’s the fun part.
Kinect code is written in C# and run on Win7/64 PC. I use example from Kinect SDK. Arduino part is written in Arduino C. They communicate via Serial-over-USB.

Sadly, it is little too late for Halloween. Never mind, I already have a REALLY CRAZY idea for the next year!

People are asking for source codes. Sure, no problems!

Download All Sources

PC sources include Kinekt project and standalone WinForms project for testing communications with Arduino (testing servo operations from Kinekt is quite inconvinient)

If you want to use Kinekt sources, download the toolkit from MS web site and compare project FaceTrackingBasics-WPF with my sources using something like WinMerge. You will see what did I change.

Arduino part is missing code that checks for non-“0”. But it works. The idea was – if there is bad package, or PC-Arduino get out-of-sync, Arduino shall skip bad data and re-sync. However, code works just fine without it, so I never added the last few lines of code.
(do you remember programming Int14 in MS DOS? That thing required all kind of SW recovery and yet worked unreliably, or maybe I just had some bad hardware). Anyways, I tell to myself: it is not broken, so do not fix it.

Oh, and communication protocol is very simple. PC sends to Arduino 3 bytes over and over:
0x00, X, Y

X and Y are in a range from 1 to 255

Enjoy!

Jun 30

Reverse a video

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I captured a video I wanted to play backwards. I also wanted it to be played slower than it was captured.
I know how to make it slower – Windows Live Movie Maker does an excellent job (“Speed” dropdown in Edit tab).
It cannot reverse the video though
I found instructions on the internet to run an Avisynth script with Reverse, but it is not very smart about codecs (all I got is codec errors).
Then I found instructions to do it step-by-step. First, I slowed the video with Mindows Live Movie Maker. Then I converted it with VLC. Then I decompressed it with Avidemux. Then I revered it with older version of Avidemux as new version (2.6) no longer supports reverse (no kidding! I’m glad I still have 2.5!) and compressed it.

Here is the result:

Then I thought: hmm, there should be an easier way. I tried all free video editors – they all both unusable and do not have this feature. Then I found VideoPad.
VideoPad has free license for personal use. It also has an option to change clip speed in “Effect” menu (10x is the limit, but I can live with it). It also has a checkbox for “Reverse”.
It is exactly what we need, right?
Sadly, it does not work. Video is ugly, shaky, badly interlaced, and jumps back and forward in time.
I thought – well, may be if I slow video down with Windows Live Movie Maker, it will help? Because slowing down does not work smooth in VideoPad. No, it does not.
Next thing to try was decompression of the video before reversing. First time it decompressed into colorful noise, but after playing with codecs, I decompressed it decently. Sadly, it did not help.

The bottom line is: VideoPad is not commercial grade software, and those guys should test it before releasing and before asking money for it.

How I’m going to reverse my video next time? I guess, I will play more with Avisynth, figure out codecs issues and write a script.