Thread by @tech963

I ordered some really cool things from ebay two days ago, and one of them is something I've wanted to get for *years* now, so let's take a quick look at what I ordered!

I'm gonna, of course, make a more detailed tweet about those things once they arrive, but for now I can just show what info I have on those things at the moment

So, the things I got are all for my analog video setup I've been working on for... quite a while
You can read all about it over here (samuele963.github.io/projects/retro…), though keep in mind that that page isn't complete yet, so some info is missing.

Some of the things I ordered are quite bording: BNC cables and adaptors
But then I also ordered a 7" monitor - something like this:

These are made for car cameras, as you can see from the picture, but they're just composite monitors, so I can use them with other video sources - and they're really really cheap too, so they're pretty nice monitors to have and that's why I ordered one of them.

I'd like to get a bunch of them and put them all next to each other and make them show various outputs from my Weird™ Video™ Things™, but for now I bought just one of em so I could see how good/bad they are

But anyways, that's not the coolest thing I bougt that day:
I also bought THIS:

This is a Blaupunkt DVM-1000 video mixer, which is just a rebranded version of the famous Panasonic WJ-MX10
That line of mixer also included other cool mixers like the MX12, (sort of) the AVE5 (it has some differences, but it's similar, just lower end) and the *awesome* MX50

It might be hard to see from the photos, but all of these share more or less the same feature-set and control placement - and the MX10 (the one I got) was the first one of the line, having been released in late 1988

For context: the IBM PS/2 was released a year before, the NewTek Video Toaster was to be released TWO YEARS later and here's some magazine covers from that same year:

This is important, because (as you'll see later) this mixer has quite a lot of capabilities for the time, and I thought that showing some computer mags from when the MX10 was released would make that more clear.

Btw, even though it hasn't arrived yet I thought it'd be cool to show the features this mixer has. However, there's a problem: to see how big of an impact this device had on the market it'd be useful to look at a review of the time - and of course finding one will be difficult...

So here's a December 1988 issue of the Italian "Alta Fedeltà" A/V magazine, with (oh look!) a review of the brand new Panasonic WJ-MX10!

Here's the article itself, and I think even someone who doesn't know Italian can figure out that something about the WJ-MX10 is special, given that the exclamation mark in the title.

Also, that picture just below it is *super* 80s.

So, what's so special about it? Audio mixers had been a thing for quite a long time by that point, surely making a video mixer wouldn't be too difficult?

Well, yes, but also no. Let me explain:

Here's a (very dusty) video processor bt JVC: it can do colour correction, video titling and other things, but right now we're only interested in one function it has...

...this one right here:
You can select a background colour and then you can fade or wipe (using a variety of patterns) to that colour by using a slider (there's one to wipe and a different one to fade). So this JVC device is also a video mixer, right?

Well, no, and that's because, while the JVC can mix a video source together with the background colour, it cannot mix two *different* video sources together. It does have 2 SCART inputs on the back, but those just go to a button that lets you switch which input you're working on.

It might seem as if this is an artificial limitation: the "background colour" is of course just an internally-generated video signal, so if that signal generator was replaced by a composite video input then you'd have a perfectly functional video mixer... but that's not the case.

You see, mixing two video signals is actually WAY harder than it might seem: to understand why though, we need to take a closer look at how a composite signal works

I'm only gonna cover what is necessary to explain the functional principle of that video mixer, so there's a LOT I'll leave out.
@TechConnectify has made an excellent video on how composite signals work which you should check out if you're interested:

So: a composite signal is deeply tied to how a CRT works: in short, the image is drawn on the screen following a raster, so the electron beam of the CRT goes from left to right in lines, in this way:

If we picture two separate video signals coming from 2 separate video sources, the path of the electron beam will be the same on both of them, but the actual position of the beam will be different: the images won't be synced - and thus we can't mix them together

This isn't a problem for the JVC video processor, because the internal colour generator will make sure that the signal will be synced to the incoming video source, but with a video mixer we need to be sure that the two signals will be synced... and that's hard to do

As a sidenote, you might have seen this video by @AkBKukU about a really cool Sony video processor (which works more or less the same as my JVC):

In that video Shelby took the Sony apart to try to add a video input so the device could go from a video source to the new video input instead of going to the colour backdrop video signal

Now, he didn't actually manage to make this modification, but that's ok because the two video signals would have been out of sync with one another, so the mod wouldn't have produced the desired effect.

So, how did TV stations solve this problem? Well, they did it in two ways: one was to have devices that could be synced to a common sync source. Professional cameras generally have not just the obvious video output, but also a sync input.

That way every device will be synced the same, and it is possible to transition between them without any problem.

Another way to solve this issue is by having a device that could change the sync of a video source to one from another device.

This was called a TBC (Time Base Corrector) (or, to be more specific, a variant called a frame synchroniser) and it solved that issue - but cameras and VCRs with sync inputs and TBCs were VERY expensive, definitely out of reach of the average consumer of the time.

This is why the WJ-MX10, which is labelled from the magazine I showed earlier as the FIRST consumer video mixer, was such a big deal: you didn't need to get special VCRs that could be synced together, you could just use the one you likely had at home already.

So, let's take a quick look at the controls of the MX10 (or, well, the Blaupunkt one I got... but it's the exact same thing) so we can see what it can do!

The mixer is divided into various sections, so let's start by the bottom right: the fade control.

This is pretty simple: it lets you fade the video, audio, title (if you have the external titler option), or a mix of those things to white, black or the background colour.

Then we have a small audio mixing section, where you can balance between the 2 input sources, change the volume of the main audio, of the mic and the aux input

That way you could connect a CD player to this and add background music to your family videos - pretty useful!

Then we have the main part of the mixer: the mix/fade controls. This is fairly simple, you have an A bus and a B bus, and you can assign input 1/input 2/the background colour to each of them as you please and then you can either mix or wipe between those 2 buses.

There are quite a lot of wipe patterns you can choose (17, in fact!) and you can do so from the 6 buttons on the raised section of the mixer. There you'll also find a VU meter because 80s, a "sync warning" LED and 4 A/V switching buttons, so let's see what they do:

You see, the mixer has 2 video inputs (well, technically 3 but we'll take a look at the third one a bit later), but you might want use it with just one video source, or maybe you want to swap the 2 inputs for some reason - well, you can do that easily thanks to those buttons!

Swapping the two inputs might seem like a weird thing to do, but it makes sense since the digital effect section we'll take a look at in a bit only works on the first input, so this solves that problem

(Also, the mixer only has a single TBC in it, and it uses the sync from the first input source as a reference: I suspect that this might also be a useful thing to use if you'd like to use an external switcher with the MX10 (like in my case) and you want to avoid problems)

Anyways, let's move on with the tour of the controls: up next there's a "positioner" knob, which is really just a joystick you can move around
This is useful for 2 of the 17 wipe patterns: the circle and square ones

The knob lets you choose *where* you want the circle or square to be positioned on the screen, so you can have part of an input source overlayed on the other source in a specific spot

This is really cool, but since it was 1988 it didn't actually compress the image: think of it more like adding a window onto part of the image to see another part of the other image

Still, it's a pretty nice effect to have.

Then we have the colour knob, which is just like the one on the JVC processor I have: it lets you choose between a few colours which can then be used on the other sections (for example, you can wipe between one of the inputs and the background colour).

The next section is awesome: it's the digital effects section, and it lets you add various effects to the input 1 source (this is where those switching buttons are useful):
- still frame (IN 1988!!)
- strobe
- mosaic (which just pixelises the image)
- paint

If you want to apply just part of an effect to an image (for example, let's say you wanted to pixelise the face of someone) you can just select source 1 on both the A and B bus, and then you could use the square or circle patterns and move the circle or square to the right part.

(warning: the following section contains some speculation:)

So, remember how I said that the MX10 only has one TBC?
Well, let's take a look at the AWE5, which has two TBCs:

Notice anything?

*the AVE5, whoops

And yeah, the digital effects section has two sets of buttons: one for the A bus and one for the B bus, whereas the MX10 (and the MX12) can only apply their effects to the first INPUT

And I think the fact that the last 2 only have a single TBC is related...

I was looking at the wikipedia page for how a frame synchroniser works (en.wikipedia.org/wiki/Time_base…) and I noticed something...

Quoting the text on wikipedia:
"The synchronizer accomplishes this by (first digitizing in an analog scenario and) WRITING THE INCOMING DIGITAL VIDEO INTO A FRAME BUFFER MEMORY using the timing of the sync information contained in that video signal. "

So this is why the mixer has a built in freezeframe effect: it needs a framebuffer anyways for the synchroniser, so why not just add a freeze frame button?

I presume that this is also why TBCs were so expensive: they needed a LOT of memory.

And for the other effects, well, they probably weren't all that hard to make by just using a microprocessor - the hard part was getting the memory there in the first place

Since the AVE5 has 2 TBCs (source: this awesome 1991 video: ) it can have two sets of effects - making it better, at least in that sense, than the MX12 (which was more or less the S-Video version of the MX10).

This also means that the AVE5 would probably be better suited to use with video switchers, since the second input doesn't need the first one to be present to be synced

The AVE5 is kinda worse than the MX12 in other aspects though: mainly build quality, the MX12 looks much more professional and it has a proper T-bar instead of the small slider on the AVE5.

Plus the AVE5 didn't have knobs to select how "much" of an effect you wanted, you just had to press a button multiple times, which meant you couldn't decrease an effect... and that's really not great IMO.

Plus apparently the AVE5 could overheat if left on for too long🙃

Anyways, let's finish the overview of the control section of the MX10;
the next part is probably one of the coolest features it has, and that is the superimpose section.

This is also where that "third input" is used - let me explain:

The video mixer has 2 main A/V inputs, as we discussed - but it also has a third input for an external camera. However, that input needs to be connected to something with a sync input or it won't work (I happen to have a camera with a sync input, so I can test that feature)

This feature would have been used for titles: you could have a camera pointed at a sign you made and that would be your title, then you could use the other two inputs like normal, without tying one of them up just for the title

Here's that control section again:
You can select the source you wanna key (between those three video sources), you can adjust the level of the key, so that you only see the parts you wanna see, there's a reverse button to invert the effect, and then there's a colour selection:

This is because this device doesn't actually do a "real" lumakey, it replaces the leftover parts of the image from the video that's being keyed into a solid colour: you can select between white or the currently selected background colour - which makes perfect sense for titles

The last button is a "title effect" button and it lets you select between different shadows and borders for your title.

And the final section on this mixer lets you select what you want to see on the main video outputs (video1, video2 or the final effect).

Overall this is a solid device and I can understand why that magazine called it a "miracle" - it was the first of its kind and it's a very interesting piece of history that I'm happy to have showed here (even though it hasn't arrived yet).

Anyways, that's all for now :)

I'll make another tweet once the stuff I ordered arrives, but until then... have a good day!