Category: General

Friday Links: How the magic happens

By Ashish Datta | Leave a Comment on Friday Links: How the magic happens

Happy holidays to everyone! Hopefully the eggnog has been flowing freely and if you’re in the Northeast you’ve been enjoying the unusually warm weather. I’d been planning to post the usual link roundup but changed my mind. I ended up seeing The Imitation Game last night and it inspired me to do something different. The movie is definitely worth seeing and if you work in technology it illuminates a connection to a shared past that most of us don’t often think about. So continuing in this theme, here are four links that’ll help explain how the actual sausage gets made.

Church–Turing thesis

This is the big one. Developed independently by Church and Turing, and eventually formalized by Kleene this axiom serves as the foundation for computer science. It lays out a framework for computation and defines the limits of what problems can be computed.
Read More >

How does a computer chip work?

Skipping over a few decades of research (and vacuum tubes) puts us at modern microprocessors. Today microprocessors are found in basically every piece of consumer electronics including your TV, car, tablet, and obviously laptop. But how do these actually work? At a fundamental level, it’s not as complicated as you think.
Read More >

Why should I learn about compilers?

Now we’ve built a microprocessor but how do we do anything useful with it? You’ve probably heard people talk about “programming languages” and a compiler is the tool that makes them magical. Read on to learn how a compiler translates text written by humans into instructions a machine can understand.
Read More >

How Does the Internet Work?

Ok we’ve established what can be computed, how processors work, and how we program them. Now we just need to get online. Unfortunately, it’s a morass of acronyms but the pieces generally fit together logically.
Read Now >

Friday Links: Obama codes, MSFT <3 BTC, and hacked k-cups

By Ashish Datta | Leave a Comment on Friday Links: Obama codes, MSFT <3 BTC, and hacked k-cups

It rained, it snowed, but hey it’s Friday! Grab some beers and snack on some links.

Now you can exchange bitcoins to buy apps, games, and more at Microsoft

It’s a post Ballmer world and Microsoft is making big moves. Starting immediately, you can use Bitcoin to fund your Microsoft account to buy apps and Xbox content. Get the details >

Async – Cooperative Multitasking for Hack

Evaluating Facebook’s new Hack programming language? Well check out how it supports cooperative multitasking. Hint: It’s pretty sweet. Read more >

Keurig 2.0 DRM Bypass

Have a shiny new Keurig 2.0 but don’t want to pay for the premium K-cups? Well KeurigHack has you covered. Get some scotch tape and drink those cups. Details here

Obama Becomes First President to Write a Computer Program

In support of CS education and the “Hour of code” project, President Obama wrote some Javascript. Rumor has it a fist bump was also involved. Read the story >

Video: Video effects with avcon and ImageMagick

By Ashish Datta | Leave a Comment on Video: Video effects with avcon and ImageMagick

A couple of months ago I was at Firebrand Saints and started wondering how the effects that they run on their videos work. At Firebrand, their main bar has a few flat screen TVs showing cable channels you’d expect but every now and then one of the TVs will start displaying the video through a filter. So as you’re sitting at the bar you’ll notice Sportcenter go from regular video to what looks like Sportcenter put through a pixelated filter. Unfortunately, the fall got a bit busy and I forgot to jot this down but it recently came back to me while watching the Family Guy – Take On Me skit.

So how do you programmatically apply effects to video? After some searching around, it seems like the preferred way to do this is to convert the video to a series of images, apply the effects, and then encode the images back to a video. Since we’re on Linux the weapons of choice for this are libav (ffmpeg fork) and ImageMagick. Additionally, I used youtube-dl to grab some source video from YouTube.

Playing around with manipulating videos and images is pretty CPU intensive so I decided to do this on a c3.xlarge. Once you have a machine up, just run the following to get everything setup:

Now, snag yourself a video from YouTube:

Next, you’ll want to extract the audio and then the individual frames from the video:

And now for the fun part – time to apply some effects to the image! As an fun first pass I ran the “paint” transform across the images. PS. Remember how we launched on that c3.xlarge? Well now we can run the transforms in parallel with xargs:

Finally, you’ll need to encode the images back together into a video format of your choice:

Here’s a clip of the video I ended up with:

So what else can you do with this? Well that’s the awesome part! An image manipulations you can do programmatically (ImageMagick, NodeJS, etc.) you can apply to your video.

Perhaps some Mystery Science Taylor Swift?

Unfortunately this adventure has left me with more questions than answers:

  • How do you apply filters to a video in real time?
  • Would it be possible to integrate this into a rooted (or stock) Chromecast?
  • Could you build something to support user interactivity? Maybe with Canvas/nodeJS?

I’d love any thoughts, input, or ideas!