Monochrome CRT And Liquid Crystal Shutter Team Up For Color Video

If you were tasked with designing a color video monitor, it’s pretty clear how you’d go about it. But what if you’d been asked to do so 20 years ago? Would it have been a cut and dried from an engineering standpoint? Apparently not, as this hybrid LCD-CRT video monitor demonstrates.

We’d honestly never heard of this particular design, dubbed “LCCS”, or liquid crystal color shutter, until [Technology Connections]’ partial teardown of the JVC monitor and explanation of its operation. The idea is simple and hearkens back to the earliest days of color TV in the United States, when broadcasters were busy trying to bring color to a monochrome world in a way that would maximize profits. One scheme involved rotating a color wheel in front of the black-and-white CRT and synchronizing the two, which is essentially what’s happening in the LCCS system. The liquid crystal panel cycles between red, blue, and green tints in time with the CRT’s images behind it, creating a full-color picture. “But wait!” you cry. “Surely there were small color CRTs back in the year 2000!” Of course there were, but they kind of sucked. Just look at the comparison of a color CRT and the LCCS in the video below and you’ll see why this system carved out a niche in the pro video market, especially for video assist monitors in the days before digital cinematography. A similar system was used by Tektronix for color oscilloscopes, too.

As usual, [Technology Connections] has managed to dig up an interesting bit of the technological fossil record and present it in a fascinating way. From video on vinyl to 1980s copy protection to the innards of a toaster, we enjoy the look under the hood of forgotten tech.

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A Raspberry Pi 4 Video Streaming Backpack

Were you aware that there’s a market for backpack-housed live streaming video systems, and that they can cost as much as $1600? Apparently these things are popular with social media moguls who want to stream themselves living their fabulous lives to people sitting at home watching on YouTube or Twitch. But believing that even slack jawed yokels like us should have access to the same technology, [Speedify Labs] has been working on less expensive DIY alternative based on the Raspberry Pi 4.

Now you’ll note we didn’t use the term “cheap” to describe this build. As detailed here, it’s still going to cost you around $600. You could always swap out the Sony AS-300 camera and Elgato Cam Link capture device with cheaper versions, but the goal of this project was to deliver high quality HD video that’s comparable to what the professional rigs are capable of, so those kinds of concessions were avoided.

Whatever video source your audience and budget are comfortable with, it eventually gets fed into the Raspberry Pi 4 which uses an ffmpeg one-liner to encode the video and ultimately push it out as 720p at 24 FPS, which [Speedify Labs] says seems to be about as good as the Pi can do. The operator is able to start and stop the stream at will using a Circuit Playground Express and a Python script.

Of course, the trick to all of this is getting the video stream uploaded over potentially flaky mobile networks. But as you might have guessed, that’s where [Speedify Labs] gets to flex their eponymous product: a VPN with software channel bonding that allows you to combine multiple Internet connections for higher bandwidth and reliability. With their software, the Pi is able to stream the video through two mobile phones connected to it over USB. As demonstrated in the video below, the setup was able to maintain the stream even as they walked in and out of buildings.

Our very own [Lewin Day] wrote about his experiments with streaming video over 4G on the Raspberry Pi which might be of interest to anyone looking to take their show on the road. Though if you want to get serious it would be worth taking a look at the impressive mobile streaming rig that [Jenny List] saw at the BornHack 2019 hacker camp in Denmark.

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Speeding Up Drawing To MCU-Connected Serial Displays

Writing image data to serially connected (SPI/I2C) displays from a microcontroller is easy enough these days, courtesy of standards defined by the MIPI Alliance, yet there are some gotchas in it which may catch someone using it unaware. [Larry Bank] wrote up a good summary of how one can get maximum performance out of such a display link.

At the core is the distinction between pixel data and command transmissions. The change from command to pixel data mode requires signaling, which takes precious clock cycles away from transferring pixel data between the MCU and display. The common MIPI DCS instruction set allows for a big reduction in needed data transfers by allowing parts of the display to be addressed instead of requiring a full refresh. Yet by not properly segmenting command and data transfers, one ends up unnecessarily slowing down the process.

The result is that one can run something like a Pac-Man emulator on an AVR MCU with a sluggish 320×480 SPI LCD at 60 FPS, as one can see in the video that is embedded after the break. Check the article for another demo video as well.

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RCA Created Video Records Too Late

It is easy to find technology success stories: the PC, DVD, and cell phone are all well-documented tales. However, it is a little harder to find the stories behind the things that didn’t quite take off as planned. As the old saying goes, “success has many parents but failure is an orphan.” [Technology Connections] has a great video about RCA’s ill-fated SelectaVision video disc systems. You can see part one of the video below.

RCA started working on the system in the 1960s and had they brought it to market a bit earlier, it might have been a big win. After all, until the VCR most of us watched what was on TV when it was on and had no other options. You couldn’t record things or stream things and f you didn’t make it home in time for Star Trek, you simply missed that episode and hoped you’d get luckier when and if they reran it during the summer. That seems hard to imagine today, but a product like the SelectaVision when it was the only option could have really caught on. The problem was of course, that they waited too late to bring it to market. The video also makes the point that the system contained a few too many technical compromises.

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10-Way Game Console Lets Everyone Play

[Bitluni]’s motto seems to be, “When you’re busy, get busier.” At least that would explain adding even more work to his plate in the run-up to the Hanover Maker Faire and coming up with a ten-player game console from scratch.

As for this being extra work, recall that [bitluni] had already committed to building a giant ping pong ball LED wall for the gathering. That consisted of prototyping a quarter-scale panel, building custom tooling to get him past the literal pain point of punching 1200 holes, and wiring, programming and testing the whole display. Building a game console that supports ten players at once seems almost tame by comparison. The console is built around an ESP32 module, either WROOM or WROVER thanks to a clever multifunctional pad layout on the slick-looking white PCBs. [bitluni] went with a composite video output using the fast R-2R ladder network DAC that he used for his ESP32 VGA project. The console supports ten Nintendo gamepads for a simple but engaging game something like the Tron light cycles. Unsurprisingly, players found it more fun to just crash into each other on purpose.

Sure, it could have been biting off more than he could chew, but [bitluni] delivered and we appreciate the results. There’s something to be said for adding a little pressure to the creative process.

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An All-In-One Conference Video Streaming Box

When running a hacker camp or other event, one of the many challenges faced by the organisers concerns the production and distribution of event videos. As the talks are recorded they must be put online, and with a load of talks to be processed it quickly becomes impractical to upload them one by one through a web interface such as that provided by YouTube. At the BornHack 2019 hacker camp in Denmark they were using a particularly well-integrated unit to do the video uploading in real time, and its creator [Mikkel Mikjær Christensen]  was good enough to share the video we’ve put below the break, a talk he gave about it at The Camp 2017, a Danish open source software camp.

It takes the viewer through the evolution over several years, from simple camcorders with integrated microphones and post-event processing, through a first-generation system with a laptop and rack-mount monitors, and into a final system in a rugged portable case with a significantly powerful laptop running OBS with a hardware MPEG encoder. Careful choice of power supplies and the use of good quality wireless microphones now give instantaneous video streaming to events such as BornHack without the need for extensive infrastructure.

If you were wondering where you might have heard that name before, [Mikkel] is the [Mike] from the Retrocomputing with Mike YouTube channel. It’s being honest to say that more of our conversation was about retrocomputers than the video box.

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Building DIY Acoustic Panels To Cut Down On Echoes

Plenty of hackers and makers are passionate about content creation. In the dog-eat-ice-bucket-challenge world of online video, production value is everything. If you want to improve your audio quality then cutting down on echoes is a must, and these acoustic panels will help you to do just that. 

The build starts with aluminium L-channel, affixed together into an equilateral triangle with the help of some 3D printed brackets. Two of the triangular frames are then fitted together via a series of hexagonal standoffs. Foam or housing insulation is then added to act as the primary sound absorbing material. To give an attractive finish, the panels are covered in fabric. The panels are then placed on to drywall using nails glued into the standoffs.

While the panels are likely more expensive to build than off-the-shelf foam alternatives, they have an attractive look which is key in video studio environments. If you’re wondering where to position them for the best results, there’s a simple and easy approach to figure it out. Video after the break.

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