Video Hacks

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Gif Player Does It Using Paper Medium

November 23, 2011 by 4 Comments

Ditch that fancy wide-format LCD monitor and go back to the days when animation was made up of moving frames played back by a specialized device. [Pieterjan Grandry] built this gif player which does just that. The frames of the animation are printed on a paper disk. When spun and viewed through a looking hole the same size as one frame an animated image is formed.

If you know a thing or two about how movie projectors work you might have a raised eyebrow right now. To make the animation smooth you need a way to hide the changing of the frames. With a projector there’s usually a spinning shutter (like a fan) that covers the transition between frames. In this case, [Pieterjan] has mounted the case of the gif player far enough in front of the paper disk that the image is in shadow, making it hard to see. A microcontroller responsible for the speed of the spinning disk flashes some white LEDs with precise timing which gives light to each frame at just the right time.

This is really a 2D equivalent to the 3D stroboscope we saw a few days ago.

[Thanks Agtrier]

Monitoring Batch Jobs The Cylon Way With Python And A Parallel Port

November 18, 2011 by 14 Comments

parallel-port-trigger

If you happen to do a lot of video encoding, you know that your computer can really drag while the process is carried out. Our own [Mike Szczys] transcodes videos at home fairly often, and because the process is automated, he doesn’t always know if a conversion is taking place in the background.

He has been tinkering with Larson Scanners recently and thought he could put everything he’s learned along the way to good use by using the scanner as a “busy” indicator for his PC. He hooked the scanner up to the computer’s parallel port, and took a few minutes to bang out some Python code that would alert him when his PC was busy.

He set his notifier script to launch along with FFMPEG, whenever his MythTV setup had something ready to convert. The Python script drives a pin on the parallel port high, triggering the Larson Scanner’s animation. Every minute, the script checks the status of FFMPEG and continues to hold the pin high until the application exits. Once the conversion is done, the scanner goes back to sleep, letting [Mike] know that the coast is clear.

Check out the video below the break to see his parallel port trigger in action.

Continue reading “Monitoring Batch Jobs The Cylon Way With Python And A Parallel Port” →

Video: Interrupts On The ATmega328p

November 17, 2011 by 1 Comment

This week, we are bringing you the final video in our series where [Jack] uses the 3pi robot as a fancy development board for the ATmega328p processor. Today’s video deals with interrupts. If you have been wanting to have your programs do more than one thing simultaneously, interrupts are the solution. [Jack] discusses various ways that you can use interrupts in your programs and then shows how he created a interrupt routine that drives the 3pi’s beeper. He also shows the routines that enable, disable, and control the interrupt.

Since this is the last post for this series of videos, we are posting the code used for all of the previous videos. Click here to grab a copy.

For our next series of videos, we are going to attempt something more challenging so most likely we will be taking a couple of weeks off to do some development before presenting it here. Stay tuned folks, we’ll be back.

Video is after the break…

In case you missed any of the previous videos, check out these links:

Part 1: Setting up the development environment
Part 2: Basic I/O
Part 3: Pulse Width Modulation
Part 4: Analog to Digital conversion
Part 5: Working with the 3pi’s line sensors

Continue reading “Video: Interrupts On The ATmega328p” →

Video: Working With The 3pi Robot’s Line Sensors

November 12, 2011 by 4 Comments

This week, we are serving up part five in our series where we are using the Pololu 3pi robot as a fancy development board for the ATmega328p processor. This week we are taking a quick break from working with the perpherals specific to the processor and will show how to work with the 3pi’s line sensors. A quick look at the schematic for the 3pi might lead you to think that you should be reading the line sensors with the A2D peripheral. Even though they are wired to the A2D pins, they need to be read digitally. In the video, [Jack] will show how to read raw values from the sensors and then how to calibrate the results so that you can get a nice clean 8-bit value representing what the sensors are seeing. Of course, that would happen under normal circumstances. Murphy had his way in this video and it turned out that our studio lighting was interfering a bit with the sensor readings when we were shooting so we didn’t get as good of a calibration as we would have liked when we shot.

Video is after the break.

In case you have missed the previous videos here are some links:

Part 1: Setting up the development environment
Part 2: Basic I/O
Part 3: Pulse Width Modulation
Part 4: Analog to Digital conversion

Continue reading “Video: Working With The 3pi Robot’s Line Sensors” →

Ghostly Images Appear Thanks To Projections On Fog

November 12, 2011 by 28 Comments

This wire-frame cube appears to be floating in mid-air because it actually is. This is a project which [Tom] calls a Laminar Flow Fog Screen. He built a device that puts out a faint amount of fog, which the intense light from a projector is able to illuminate. The real trick here is to get a uniformed fog wall, which is where the laminar part comes in. Laminar Flow is a phenomenon where fluids flow in a perfectly parallel stream, not allowing errant portions to introduce turbulence. This is a favorite trick with water.

[Tom’s] fog screen starts off with a PC fan to move the air. This airflow is smoothed and guided by a combination of a sponge, and multiple drinking straws. This apparatus is responsible for establishing the laminar flow, as the air picks up fog from an ultrasonic fogger along the way.

The only real problem here is that you want the projector shooting off into infinity. Otherwise, the projection goes right through the fog and displays on the wall, ruining the effect. Outdoor applications are great for this, as long as there’s no air movement to mess with your carefully established fog screen.

You can find a short test clip embedded after the break but there are other videos at the link above.

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Big Head Costume Would Make Max Headroom Jealous

November 9, 2011 by 21 Comments

big-head-halloween

[Dan Rosenfeld] does a lot of thinking in his spare time, and one thing he returns to pretty often is videoconferencing. He’s often wondered why it hasn’t caught on enough to become a ubiquitous piece of technology, and his examination of the topic in regards to eye contact and spatial awareness inspired him to create a very unique Halloween costume.

His “Big Head” costume consists of a front-mounted 24” LCD panel that displays the wearer’s face in real time. Inside the large headpiece [Dan] installed a microphone, another LCD screen, a half silvered mirror, and a video camera – not to mention all of the power-related goodies required to keep it running. While the main LCD displays his face, the internal monitor is fed by an externally mounted camera that shows him everything going on outside the box. This image is reflected off the half silvered mirror, allowing him to gaze directly at the camera, while also seeing what’s going on in front of him.

As you can see in the video below, the effect is pretty cool, and devoid of the ‘disconnected’ look most people have when talking to others via a camera and computer screen.

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Video: Analog To Digital Conversion On The ATmega328p

November 3, 2011 by 6 Comments

In this week’s video, we continue on where we left off last week with another in our series of videos where we discuss how to program for the ATmega328p processor. This week, [Jack] takes a look at the analog to digital converter and takes us through how to set things up and then how to perform a conversion using the potentiometer on the 3pi as the analog source. Playing with potentiometers isn’t the most interesting thing in the world, but after watching this video, you will be able to do things like take light readings using a cadmium sulfide cell, read the weight applied to a sensor, calculate the temperature from a resistor and a thermistor, or interface with an analog gyroscope.

If you have missed our previous videos, here are some links:
Part 1: Setting up the development environment
Part 2: Basic I/O
Part 3: Pulse Width Modulation

Stay tuned for next week’s* video where we will take a look at how to interface with the 3pi’s line sensors.

Video is after the break…

* HAD is in the process of moving our secret headquarters so next week’s video may come some time later than next week.

Continue reading “Video: Analog To Digital Conversion On The ATmega328p” →