More Than Technical

Posts Tagged ‘programming’

A very basic feature that I was missing in my Android phone is the ability to save a number while I’m in a call. Sure you can go to the home screen, and open up any app with a textbox, but I decided to create a dedicated application.

So, meet Number Saver!
(Source code is available at our SVN at http://code.google.com/p/morethantechnical )

Basic usage guide:

When you open the app you will get the main screen:

From here you are able to enter the number, copy to the clipboard, and clear the clipboard if it is full. Also, when you open the app, if there is a text in the clipboard it will already be in the text box. So you can press Dial to instantly dial the number

Also, during an active call you will notice the note and pencil icon. Stretching the notification area will give you the option to launch the application.

This app is available for free through the Android market

As a part of my work, I was asked to create a semi-simulator for JNLP (Web-Start) loader.

The intention was to get the JNLP link, get all the necessary JARS and resources, and send the main class to another process that will run it as a host.

I had no previous in

troduction with JNLP what so ever… Well, first stage: look at the file.

Looking at the file revealed a simple XML file that contained all the necessary data.

So of course, first things first – Get all the JARS. But how?
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Hi

I have been playing around with NyARToolkit’s CPP implementation in the last week, and I got some nice results. I tried to keep it as “casual” as I could and not get into the crevices of every library, instead, I wanted to get results and fast.

First, NyARToolkit is a derivative of the wonderful ARToolkit by the talented people @ HIT Lab NZ & HIT Lab Uni of Washington. NyARToolkit however was ported to many other different platforms, like Java, C# and even Flash (Papervision3D?), and in the process making it object oriented, instead of ARToolkit procedural approach. NyARToolkit have made a great job, so I decided to build from there.

NyART don’t provide any video capturing, and no 3D rendering in their CPP implementation (they do in the other ports), so I set out to build it on my own. OpenCV is like a second language to me, so I decided to take its video grabbing mechanism wrapper for Win32. For 3D rendering I used the straightforward GLUT library which does an excellent job ridding the programmer from all the Win#@$#@ API mumbo-jumbo-CreateWindowEx crap.

So let’s dive in….
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Hi

Just wanted to report on a breakthrough in my iPhone-CV digging. I found a true realtime frame grabber for the iPhone preview frame (15fps of ~400×300 video), and successfully integrated this video feed with a pure C++ implementation of the MeanShift tracking algorithm. The whole setup runs at realtime, under a few constraints of course, and gives nice results.

Update: Apple officially supports camera video pixel buffers in iOS 4.x using AVFoundation, here’s sample code from Apple developer.

So lets dig in…

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As my search for the best platform to roll-out my new face detection concept continues, I decided to give ol’ Qt framework a go.

I like Qt. It’s cross-platform, a clear a nice API, straightforward, and remindes me somewhat of Apple’s Cocoa.

My intention is to get some serious face detection going on mobile devices. So that means either the iPhone, which so far did a crummy job performance-wise, or some other mobile device, preferably linux-based.
This led me to the decision to go with Qt. I believe you can get it to work on any linux-ish platform (limo, moblin, android), and since Nokia baught Trolltech – it’s gonna work on Nokia phones soon, awesome!

Lets get to the details, shall we?
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Recently I was working on an iPhone app for work, for demo purposes, but my company cheaped out on the Apple iPhone Developers registration. 

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Hi

I had a little project at work recently, that involved creating movie clips using AviSynth.
And I was appalled by the shabbiness of existing transition plugins available freely for AviSynth, they always reminded me of 80s-like video editing…
So I set out to integrate AviSynth with OpenGL to create a nice 3D transition effect for our movie clips.

I had 2 major bases to cover:

• AviSynth plugin API
• OpenGL rendering

AviSynth API is not so well documented, but they have very good ground-up examples on how to DIY plugin. Here is the one I used, that basically does nothing but copy the input frame to the output frame.
Open GL on the other hand is very well documented and “tutorialed”. I based my code on this example from NeHe.

So basically what I wanted to achive is:

1. Read input frame (AviSynth)
2. Paint frame as texture over 3D model (OpenGL)
3. Draw rendered 3D image to output frame (OpenGL+AviSynth)

Reading the frame is pretty straightforward. Frames come encoded as RGB 24bit, with a little twist: rows size in bytes is not width*3 as you’d expect it be, but AviSynth use a parameter called “Pitch” to determine row size in bytes.

Update (14/9/09): source is now available in the repo: browse download
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I recently had to build a demo client that shows short video messages for Ubuntu environment.
After checking out GTK+ I decided to go with the more natively OOP Qt toolbox (GTKmm didn’t look right to me), and I think i made the right choice.

So anyway, I have my video files encoded in some unknown format and I need my program to show them in a some widget. I went around looking for an exiting example, but i couldn’t find anything concrete, except for a good tip here that led me here for an example of using ffmpeg’s libavformat and libavcodec, but no end-to-end example including the Qt code.

The ffmpeg example was simple enough to just copy-paste into my project, but the whole painting over the widget’s canvas was not covered. Turns out painting video is not as simple as overriding paintEvent()…

Firstly, you need a separate thread for grabbing frames from the video file, because you won’t let the GUI event thread do that.
That makes sense, but when the frame-grabbing thread (I called VideoThread) actually grabbed a frame and inserted it somewhere in the memory, I needed to tell the GUI thread to take that buffered pixels and paint them over the widget’s canvas.

This is the moment where I praise Qt’s excellent Signals/Slots mechanism. So I’ll have my VideoThread emit a signal notifying some external entity that a new frame is in the buffer.
Here’s a little code:

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I was recently building a simple GUI in .NET to operate an algorithm as part of a school project, and I encountered a weird problem using BackgroundWorkers. I spent a lot of time debugging it, mainly because the code seemed to be perfect (which was true) but the run-time behavior was so strange…

Anyway, to make my algorithm as weakly-coupled as possible decided not to use ‘BackgroundWorker.ReportProgress‘, because then my algorithm will have to know what a BackgroundWorker is…
I decided to actually fire my own event whenever I wanted to report on the algorithm progress (which is rather lenghty). So I defined my delegate and event inside my one-function class that runs the algorithm:

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