A Bullet Time Video Booth You Can Build

May 27, 2023 by Dave Rowntree 8 Comments

[Sebastian Staacks] built a video booth for his wedding, and the setup was so popular with family, that it was only fitting to do one better and make some improvements to the setup, Matrix-style. The “bullet time” video effect was introduced by the classic movie franchise and makes for a splendid video transition effect for video montages.

Hardware-wise, the effect is pretty expensive, requiring many cameras at various angles to be simultaneously triggered, in order to capture the subject in a fixed pose with a rotating camera. Essentially you need as many cameras as frames in the sequence, so even at 24 frames per second (FPS), that’s a lot of hardware. [Sebastian] cheated a bit, and used a single front-facing camera for the bulk of the video recording, and twelve individual DSLRs covering approximately 90 degrees of rotation for the transition. More than that is likely impractical (not to mention rather expensive) for an automated setup used in as chaotic an environment as a wedding reception! So, the video effect is quite the same as in the movies, as this is a fixed pose, but it still looks pretty good.

A Pico-W hidden in there providing a BT connected interface button

[Sebastian] did consider going down the Raspberry Pi plus Pi-cam route, but once you add in a lens and the hassle of the casing and mounting hardware, not to mention availability and cost, snagging a pile of old DLSRs looks quite attractive. Connectivity to the camera is a simple 3.5 mm jack for the focus and trigger inputs, with frames read out via a USB connection.

For practical deployment, the camera batteries were replaced with battery eliminator adapters which step-up the 5 V from the USB connection to the 7.4 V the cameras need, but the current spike produced by the coordinated trigger of all twelve cameras overwhelmed any power supply available. The solution, to be practical, and not at all elegant, is to just have lots of power supplies hidden in a box. Sometimes you’ve just got a job to do.

Reproducing this at home might be a bit awkward unless you have exactly the same hardware to hand, but the principles are sound, and there are a few interesting details to dig into, if you were so inclined.

We’ve seen a few takes on the bullet-time effect over the years. We featured a Raspberry Pi-based hack, a couple of years back, and earlier still, someone even built a rig to take bullet-time videos of Tesla coil discharges, because why not?

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Inside A Pair Of Smart Sunglasses

May 6, 2023 by Bryan Cockfield 14 Comments

If you’re willing to spend $200 USD on nothing more than 100 grams of plastic, there are a few trendy sunglasses brands that are ready to take your money before you have time to think twice. Sure, you can get a pair of sunglasses for an order of magnitude less money that do the exact same job, but the real value is in the brand stamped into the plastic and not necessarily the sunglasses themselves. Not so with this pair of Ray-Bans, though. Unlike most of their offerings, these contain a little bit more than a few bits of stylish plastic and [Becky Stern] is here to show us what’s hidden inside.

At first glance, the glasses don’t seem to be anything other than a normal pair of sunglasses, if a bit bulky But on closer inspection they hide a pair of cameras and a few other bits of electronics similar to the Google Glass, but much more subtle. The teardown demonstrates that these are not intended to be user-repairable devices, and might not be repairable at all, as even removing the hinges broke the flexible PCBs behind them. A rotary tool was needed to remove the circuit boards from the ear pieces, and a bench vice to remove the camera modules from the front frame. We can presume these glasses will not be put back together after this process.

Hidden away inside is a pair of cameras, a Snapdragon quad-core processor, capacitive touch sensors, an amplifier for a set of speakers. Mostly this is to support the recording of video and playback of audio, and not any sort of augmented reality system like Google Glass attempted to create. There are some concerning ties with Facebook associated with this product as well which will be a red flag for plenty of us around here, but besides the privacy issues, lack of repairability, and lack of features, we’d describe it as marginally less useful as an entry-level smartwatch. Of course, Google Glass had its own set of privacy-related issues too, which we saw some clever projects solve in unique ways.

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Pulling Data From HDMI RF Leakage

March 7, 2023 by Jenny List 25 Comments

A long-running story in the world of electronic security has been the reconstruction of on-screen data using RF interference from monitors or televisions. From British TV detector vans half a century ago to 1980s scare stories about espionage, it was certainly easy enough to detect an analogue CRT with nothing more than an AM broadcast radio receiver. But can this still be done in the digital age? It’s something [Windytan] has looked into, as she reconstructs images using leakage from HDMI cables.

The tale starts with a mystery RF noise, soon identified as not unlike the scanning frequencies of a video signal. Plotting the noise intensities while treating the supposed scanning frequencies as video synchronization yields a shadowy version of her Raspberry Pi desktop, so she’s on to something. It’s important to note that this isn’t a video signal she’s receiving, but the noise associated with the bit transitions in an uncompressed digital video stream, so she quickly concludes that trying to resolve color would be futile.

It does however leave the tantalizing possibility of using this as a medium to wirelessly export data from a compromised machine, and it’s down this route she goes. She finally arrives on a scheme of encoding data as lines of individual colors that look like interference patterns over a desktop, and from there can send and retrieve files. It works for digital audio streams, and as shown in the video below, even an MJPEG video stream, hidden in the noise from a video signal. That’s impressive work, by any standard!

We covered those BBC detector vans in detail a while back.

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Connecting A Keyboard To A Vintage PC-XT, The Hard Way

February 7, 2023 by Dan Maloney 15 Comments

We’re not sure if there’s any single characteristic that qualifies someone as a hacker. After all, we’re a pretty eclectic bunch, with skills that range all over the map, and what one person feels is trivial, others would look upon as black magic. But there’s one thing we’re sure of: if you find yourself reading the original POST code for the PC-XT motherboard just to get a keyboard working, you’re pretty much our kind of people.

That was the position [Anders Nielsen] found himself in as work progresses on his “PC-XT from Scratch” project, which seeks to build a working mid-80s vintage IBM Model 5160 using as many period-correct parts as possible. The first installment of the series featured the delicate process of bringing the motherboard up, lest the magic smoke was released. After seeing some life out of the old board, [Anders] needed a little IO, specifically video and keyboard. The video side of the equation was relatively trivial, with an early-90s VGA card from eBay — not exactly period correct, but good enough to get something to display. Continue reading “Connecting A Keyboard To A Vintage PC-XT, The Hard Way” →

DIY Macro Keyboard Wood Be Nice

January 25, 2023 by Bryan Cockfield 13 Comments

Editing video tends to involve a lot of keyboard shortcuts, and while this might be fine for the occasional edit, those who regularly deal with video often reach for a macro pad to streamline their workflow. There are plenty of macro keyboards available specifically meant to meet the needs of those who edit a lot of video, but if you want something tailored for your personal workflow you may want to design your own keyboard like this wooden macro pad from [SS4H].

The keyboard itself is built around an STM32 microcontroller, which gives it plenty of power to drive and read the keyboard matrix. It also handles an encoder that is typically included on macro keyboards for video editing, but rather than using a potentiometer-type encoder this one uses a magnetic rotary encoder for accuracy and reliability. There’s a display built into the keyboard as well with its own on-board microcontroller that needs to be programmed separately, but with everything assembled it looks like a professional offering.

[SS4H] built a prototype using 3D printed parts, but for the final version he created one with a wooden case and laser etched keys to add a bit of uniqueness to the build. He also open-sourced all of the PCB schematics and other files needed to recreate this build so anyone can make it if they’d like. It’s not the only macro keyboard we’ve seen before, either, so if you’re looking for something even more esoteric take a look at this keyboard designed to be operated by foot.

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Generating PAL Video With A Heavily Overclocked Pi Pico

January 24, 2023 by Dave Rowntree 19 Comments

Barely a week goes by without another hack blessing the RP2040 with a further interfacing superpower. This time it’s the turn of the humble PAL standard composite video interface. As many of us of at least a certain vintage will be familiar with, the Phase Alternate Line (PAL to friends) standard was used mainly in Europe (not France, they used SECAM like Russia, China, and co) and Australasia, and is a little different from the much earlier NTSC standard those in the US may fondly recollect. Anyway, [Fred] stresses that this hack isn’t for the faint-hearted, as the RP2040 needs one heck of an overclock (up to 312 MHz, some 241% over stock) to be able to pull off the needed amount of processing grunt. This is much more than yet another PIO hack.

The dual cores of the RP2040 are really being pushed here. The software is split into high and low-level functions, with the first core running rendering the various still images and video demos into a framebuffer. The second core runs in parallel and deals with all the nitty-gritty of formatting the frame buffer into a PAL-encoded signal, which is then sucked out by the DMA and pushed to the outside world via the PIO. There may be a few opportunities for speeding the code up even more, but [Fred] has clearly already done a huge amount of work there, just to get it working at all. The PIO code itself is very simple but is instructive as a good example of how to use multiple chained DMA channels to push data through the PIO at the fastest possible rate.

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