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Create Standard Definition Video files for Raspberry Pi

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For the past few years I’ve been creating weird videos that (often) celebrate retro-computing with modern day low-power computing by making a Raspberry Pi connected to an old Apple display monitor play videos. You may remember Apple Watch and Apple Wait from past years of Maker Faire Milwaukee.

I’ve struggled a bit with the process of using modern software to create low-resolution videos, and I’m sure there is more than one way to do it, but I thought I’d document my process so that the next time I do it I’ll have a simple guide to follow. I’m calling this my “Guide to creating Standard Definition Video files for Raspberry Pi”.

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When I create a new video file in Final Cut Express (yeah, I’m still using it) I just pretty much assume I’ll want an HD version, so that’s what I create, even if I plan to have a standard definition video as my final output. Video files get created at 1920×1080, also known as “1080”, for short. Let’s make a 1920×1080 file in Photoshop.

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Our final file will be 640×480, but since SD is 4:3 versus HD which is 16:9, we need to adjust for that. If we put in 480 for the height of the file, we see it proportionally scales down the width to 853. (I remember this number from my video editing days!)

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853 isn’t what we want… we want 640, so subtract 640 from 853 and what do you get? Well, it’s 213. Maths, duh! (Remember, we’re going from 16:9 to 4:3 aspect ratio, so we need to lose some of the image.)

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Divide that 213 in half and we get 106.5, but since we need an integer and not a floating point, we will use two numbers, 107 and 106. Those are the number of pixels we need to crop from our video file.

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I still use MPEG Streamclip because, wow, it’s awesome and it works. I’ve highlighted all the important settings I need to care about. We are loading in our full HD (1080) video file, and then scaling it down to 853×480 and also cropping it, 107 pixels on the left, and 106 pixels on the right. (Selecting “Deinterlace Video” can help too, depending on the look you want.)

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If the export preview from MPEG Streamclip looks wrong, you probably did something wrong. If it looks right, then you are probably in luck! Once your MP4 file is saved, you can check it out.

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I open it with QuickTime Player to check the resolution. It’s 640×480, so everything is good. So now I’ve got a Standard Def 640×480 MP4 video file that is all set to be played on a Raspberry Pi connected via composite video to an old fashioned 4:3 video display.

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PCBWay Prototyping Service

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The crew at PCBWay got in touch with me to see if I’d like to try out their service. I’ve used other PCB manufacturers in the past, so I figured I’d give PCBWay a try to see how they worked. The ordering process was not the smoothest, but the boards turned out well, were very affordable, and they got to me pretty quickly.

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I designed this PCB years ago and I’ve used them a lot in my noisemakers and while I might modify them in the future, they are still pretty useful, so I figured I’d make more.

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I had my Gerber files ZIP’d up and ready for upload, so I started the process with PCBWay, which I assumed would be similar to other PCB manufacturers I’ve used. Yup, pretty close. Note that for color you can choose green, red, yellow, blue, white, black, or “none” at the same cost, but choosing purple, matte green or matte black cost bit more. (Not quite double, but more than just a few bucks.) I’m not sure what “none” looks like, but I am curious.

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So I added the boards to my cart, and I first noticed that I could not change the quantity. This was a little annoying, as I wanted to try different quantities to see how it affected the price. You can do that, but only at the first step in the process, at the “Online Quote” step, not once it’s in your cart, so make sure you know how many you want before your add them to your cart!

When I went to checkout I then found out I could not check out. Right, seems my boards were “Subject to audit.” Yes, they had to be approved by someone (a human I guess) before I could order them, which seemed weird. (Notice the yellow highlighting I added to the cart image above.)

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Now, this is partially my fault, as I didn’t see this the first time I uploaded files. There is a little bit of text on the upload form that shows it could take “10min to 1 hours” for approval. I’m not sure exactly how long it took, as I did this late one night and didn’t get an email about approval until the next day. This was the most annoying part of the ordering process. When I want to order something I don’t want to have to wait hours, or even one hour between putting it in my cart and being able to order it. Perhaps they could make it so that you can place your order, and then if not approved for some reason (?) they could refund the order. Or who knows, maybe this whole “approval” thing is due to some new tariff laws. I have no idea.

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Like I said, pricing is good. I got 75 boards for $32. That’s about 43 cents per PCB. These are tiny boards though, so obviously the price per board goes up when you get larger boards. With approval completed (by some human, I guess) I was able to move on to shipping options.

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I went with shipping via DHL, which came in at $21, so the order total for 75 boards ended up being $53, making each board cost approximately 71 cents. (Obviously ordering more would probably bring that price down, but I really doubt I need more than 75 of these right now.)

I uploaded the PCB files on July 21st, and they were approved and ordered by July 22nd. Manufacturing was completed by July 25th and they were then shipped via DHL July 27th and I got them by July 30th. That’s about an 8 day turnaround for these printed circuit boards. (With some weekend days in there.) Not bad! For US shipping DHL is probably the best option for getting them fast. There were two cheap shipping options, one being an ePacket (which seems to be how I get most of my eBay electronics delivered) which was $8 but had a 10 to 15 day delivery time frame. There was also “China Post” option which was $7 but showed 25 to 40 days for delivery. Wow. So the ePacket is not too bad if you do not need your boards in a hurry.

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The boards from PCBWay look good and got to me fast. They were also very affordable. Overall it was a good experience except for the issue of having to wait until files were approved before ordering and not being able to change quantities once the item is in your cart.

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LinkDump 2018-08-17

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What time is it? It’s time for another LinkDump post. Not familiar with link dumps? They’re blog posts that link to other things on the World Wide Web, and often have little to no commentary. Every now and then I’ll just post some links to things I’ve read or looked at or need to check out in the future, or just want to share.

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A Concrete Bolt

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When last you saw my cast bolt it was made from plaster and an ABS 3D print which served as a mold. It sort of worked. As mentioned, it was more “art object” than “functional thing” and that was what I was going for…

Well, I made another ABS mold from the first experiment and even though I had worked with a flexible filament mold I thought I would give the ABS version one more try, this time with concrete instead of plaster.

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I really liked the way this one turned out. Yes, I had to destroy the mold again, and in the process the part got damaged and broken, and then I pulled out the hot glue gun and put it back together, and now I like it even more!

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It’s one of those situations where things go wrong so you just do something and it turns out (possibly) better than you thought it would. I joked that this was the modern maker equivalent to Kintsugi, using hot glue instead of gold.

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I really like how it has this feel of being an ancient relic. In a strange twist of fate, I was at first annoyed with all the tiny pebbles in the concrete, so much so that I made a sifter to remove them, but now I’m thinking up a list of things I can mix into the concrete besides pebbles (and, probably pebbles too.)

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Water Bottle Repair

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I bought a water bottle about two years ago after my old one was stolen (I know, who steals a water bottle!?) While the new bottle was much better, since it was insulated and could keep water cold for more than a day (with ice added in) one of the things I didn’t like about it was a small rubber ring used to seal the cap. The rubber ring had a split in it (maybe to assist with the seal?) and it was difficult to clean, and eventually it broke from attempts to vigorously clean it.

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I replaced the sealing ring by 3D printing a small mold and then casting a replacement using Smooth-Sil™ 940 silicone. The silicone is a two part mold, with a volume of 100:1 for part B to part A, which is why you get a giant tub of silicone along with a small bottle of whatever the red stuff is.

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This was my first silicone casting at home for a personal project. I’ve done casting at work for prop making, but this time I didn’t have a vacuum chamber, and I was doing a tiny part all by myself.

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So how did it turn out? Pretty good! I used a digital scale and filled a cup with 10 grams of part B, then added 1 gram of part A and mixed it all up with a popsicle stick and smeared it into the cavity of the 3D printed PLA mold. I let it sit overnight then used a sharp knife tip to pry it out. There was a thin skin around the piece but it peeled right off.

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So how does it fit? It’s good but not perfect. If I make another one I may decrease both the inside diameter and outside diameter. It could fit a bit more snug, and it could have just a wee bit more clearance when inserting into the bottle. (I’m guessing between 0.1mm and 0.2mm, maybe)

I’ve got plenty more silicone, and it is food-safe, so I want to experiment with making some food molds, and yeah, I’ll probably 3D print the objects to create the molds from, taking a page from Anna Kaziunas France.