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#1 2014-09-28 20:55:36

bbraun
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Registered: 2014-05-29
Posts: 1,064
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Live video editing?

I was wondering if there is such a thing as live video editing on either 68k or ppc macs.  Maybe with something like the Radius VideoVision?  Since I have my cable TV network setup, I was thing of doing something like a channel guide or maybe some video overlays or closed captioning information with it.  It also seems like there's a ton of composite/svideo capture/output hardware available for that era of machines, so was wondering if anyone knew where to get started with such a thing.

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#2 2014-09-29 01:09:14

ClassicHasClass
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From: Electron Alley
Registered: 2014-05-26
Posts: 1,118
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Re: Live video editing?

You mean like overlays, chyrons, etc.? I'm pretty sure such things existed, but in those days the Amiga would have been the choice.


Machine room (updated for 2019!): http://www.floodgap.com/etc/machines.html

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#3 2014-09-29 14:15:17

bbraun
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Registered: 2014-05-29
Posts: 1,064
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Re: Live video editing?

Yeah, stuff like that.  It'd also be kinda neat to rig up a system to inject notifications into the closed captioning of the channel.  I had heard Amigas were the popular for that, I just figured since there's an abundance of NTSC video capture equipment for the old macs, there'd be something for them too, even if less popular/less featureful.  I guess I need to start playing with some of the video software out there.

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#4 2014-09-29 16:21:31

jt
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From: Bermuda Triangle, NC USA
Registered: 2014-05-21
Posts: 1,470

Re: Live video editing?

ISTR having a couple of cards that did Chroma-Key overlay in real time (back then it was green screen) in NuBus Macs.

There's some great info that Cel-Gen filled me in on over at the barracks. It sounds like NuVista is probably what you're going to want, though the radius rig may do what you need.

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#5 2014-09-29 16:59:42

markyb
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From: Aurora, OH (330)
Registered: 2014-05-16
Posts: 185
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Re: Live video editing?

Weren't Apple II's used for overlays and whatnot also?
(I know not what you are looking for just asking)


http://markyb86.weebly.com for some packs of old macintosh wallpapers, desktop patterns, windows wallpapers, sound files, etc.

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#6 2014-09-30 17:11:35

techknight
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Registered: 2014-05-22
Posts: 453

Re: Live video editing?

Amiga video toaster. Thats how the local tv stations injected tornado/thunderstorm watches on screen back in the day.

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#7 2015-01-16 06:24:19

bbraun
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Registered: 2014-05-29
Posts: 1,064
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Re: Live video editing?

Well, it's no amiga toaster, and certainly isn't Mac, but I've got a bit of a hack going on this for my tv network:

It's using an arduino pro board with a video experimenter board to handle syncing things up, and then bitbanging the overlay ntsc signal.
It's supposed to be the dog from NES duck hunt, rendered in 32x32 b&w.  I'm not so great at the artistic part of this, so it looks kinda ugly.  If anyone wants to get me a better duck hunt dog, I'd be grateful.  It's just 2 frames for the laughing.

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#8 2015-01-17 01:27:47

dougg3
Member
Registered: 2014-05-27
Posts: 28

Re: Live video editing?

Totally awesome, bbraun! I notice that the white overlay is semi-transparent. How are you managing that? Are you able to force the output luma value to any value between "totally black" or "totally white"? (Obviously, the chroma is in the weird NTSC color burst so that would be pretty much impossible to change, but the transparent overlay is way cool)

Last edited by dougg3 (2015-01-17 01:29:32)

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#9 2015-01-17 01:49:12

bbraun
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Registered: 2014-05-29
Posts: 1,064
Website

Re: Live video editing?

Thanks!  The video experimenter board just keeps the sync signal in sync between the input and the sync of the output signal, and then the video signal is just wired together.  You can also do B&W bitbanged output with an arduino (which I'm doing separately for a channel guide), the VE board is just what allows the overlay.  So basically the output is "white", which is what you see in the video, and "no output", which would be black if the overlay weren't there.  No real ability to influence transparency from software.

There's a mod to use a mosfet to turn off the input video signal for portions of each scanline, so you can create black (or semi-black, depending on how effectively it blocks the input video current), so you can effectively make black boxed subtitles that way.

The resolution of the output is largely limited by the atmel 328 chip's sram, which is only 2k.  You need to keep a framebuffer for the blitting interrupt to read from, and a measly 136x96x1bpp buffer is 1.5k, the remaining 512 bytes being used for program memory.  Which is why the dog is only 32x32, but also because I started off testing by displaying Mac icons like happy mac and flashing the ? floppy icon.  The const bitmap data of the icons is stored in flash, so doesn't take up the 512bytes of ram which is nice.

The banging of the ntsc signal takes up most of the available CPU, but someone's done a hacked up serial driver to poll the UART during the vertical blanking interval, so there's some minimal, although laggy, serial capabilities to have some external input on what gets displayed.  I'm hoping to use that for my channel guide information.

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#10 2015-01-17 06:37:53

ClassicHasClass
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From: Electron Alley
Registered: 2014-05-26
Posts: 1,118
Website

Re: Live video editing?

I'll sign a contract right away. What are your monthly rates? Do you have HBO? wink


Machine room (updated for 2019!): http://www.floodgap.com/etc/machines.html

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#11 2015-01-17 07:19:19

bbraun
Member
Registered: 2014-05-29
Posts: 1,064
Website

Re: Live video editing?

The execs at this cable network really know and cater to their audience.  ME!  big_smile
This evening's update is I got the parts in for doing a non-overlay video signal from an arduino pro mini.  So I hooked it all up on a breadboard, and have a simple program to take text input from serial and display it on bitbanged NTSC.  The NTSC goes into the rf modulator (channel 19 in this case), and out to the house.  The serial side is connected to a Cyclades serial concentrator in my rack (the whole setup is racked with rackmount rf modulators and channel combiners, along with servers and stuffs), which makes serial ports network accessible.  So I can "echo text | nc cyclades" from a unixy machine, and have it display on that channel.  At the moment, it's setup doing a rudimentary channel guide with the playlist genre listed for each channel.  Maybe tomorrow I'll hack up a script to query each channel's rpi to get what file is currently playing.
Since it's only 136x96, and with an 8x8 font, that's 17x12 characters on the display, so it kinda has to do some scrolling.
Sorry for the terrible picture of the breadboard setup, it's "in production" right now.  smile
channelduino-s.jpg
channels.png

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