HDMI Video Capture Devices - following up on Baggers presentation
![Ken Gracey](https://forums.parallax.com/uploads/userpics/937/nHX7GKXF8OR2S.jpg)
Hey there,
On Tuesday Baggers showed some real gems with Chip - Space Invaders, Space Invaders 2 and Lunar Rescue.
Of course, I want to post all of the source as Quick Bytes, excluding the ROMs, which people will need to scour from the web.
I'd like to include a video capture of the games, too. I asked @Baggers how to go about this and he flashed a little black HDMI to USB video capture device. I'd like to get a couple of these to be sure I buy one that actually works (or supports whatever signals the P2 is sending it).
I'm entirely confused about the connection of these devices. If they capture the signal from HDMI, how can I see what the video capture looks like? Is there some sort of splitter device that I can use to send the same video signal to a display?
Not asking for a friend, just for my dumb honest self.
Thanks,
Ken Gracey
Comments
My understanding is that the device capture the video and then a USB driver takes in the video. With some USB software it displays it on your computer which then allows you to see the video output from the HDMI device.
From there you can capture or screen print pictures.
Mike
That part I understand.
If I want to capture a video of a game, I'd like to be playing the game to capture it with my own eyeballs AND the HDMI memory capture device. Like having two video outputs.
Ken Gracey
Every capture program has a preview window. However, due to inherent delays (desktop compositing) and how the video capture system (especially on Windows) works it will be horribly delayed (haven't ran a test, but feels like at least 4 or 5 frames delay). You can get HDMI splitter boxes though, they will allow you to run two displays off one source, no delay. Usually these have certain issues relating to handshaking, but that doesn't matter with a dumb source like the P2. If you get the right kind, a splitter box will also strip the HDCP copy protection off your bluray, netflix, pay-tv or whatever signals :) (that has to do with how an HDMI splitter works - you can't just splice the wires because that'd mess up the impedance or smth. So what they do is put a TMDS receiver IC and two transmitter ICs back-to-back. And sometimes they forget to disable the decryption support in the receiver...)
HDMI splitter. Thanks @Wuerfel_21! The frame delay won't be a problem.
Since I have you here, I think somebody in the P2 Live Forum mentioned that you've also been porting games. I haven't kept track of all the forum activity, but if you've got some links for me to look at that would be neat.
Ken Gracey
I found this: https://www.amazon.com/IPXOZO-Directly-Streaming-Conference-Broadcasting/dp/B08V86C2VT/
I think I get the idea now. The capture is happening on the device, but the display output for the human is the computer.
It wasn't this clear when I was searching earlier.
Thanks all! Case closed.
Ken Gracey
The frame delay won't be a problem.
Well, it is a problem if you're trying to play any game through the capture preview. So yeah, getting a splitter is a good idea.
I think somebody in the P2 Live Forum mentioned that you've also been porting games
Not on P2, at least, for I actually don't have one. I do have what is probably the largest collection of P1 games though, most with a description, metadata and video capture, all ready to run on my board that I eventually want to make available... I also made Spin Hexagon and am working on a real nice one (that'll likely also run on P2). Probably still years out at the current pace of development. Ask if you want to know more about that one, I can talk about it for days.
Some more game capture wisdom, mostly gathered from my adventures in P1 game cataloging:
Ken,
I use an HDMI Capture device I bought via Amazon (https://www.amazon.com/gp/product/B08C9WJKXB/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1) to capture the HDMI from the Parallax Digital Video Out accessory board. I input from that device via a USB-C adapter to my MacBookPro. On the Mac, I run the OBS application to display the P2 output to a recordable window. In this image (below), I'm playing Space Invaders, live. The OBS window is fairly configurable (I have not discovered if I can twist the screen 90 degrees, yet:-) ... I don't see a delay with this setup and I'm able to record whatever is displayed.
You could actually use this HDMI adapter and app during live Zoom meetings to share P2 video output! With a little effort, you can also record any sound from the P2, via a mic input on your computer.
Here's the entire OBS window, where you can see its options. This app can take multiple inputs & allows switching between video inputs, PC screens, cameras, etc.. And it can do this, live! It is basically a video switcher app that can be used in live/recorded video studio operations, similar to expensive Black Magic hardware & software solutions.
Recorded from the OBS app: https://youtu.be/-e3RiFUHfC8
dgately
I have not discovered if I can twist the screen 90 degrees, yet
Right click the source, rotation is somewhere under "Transform".
Also, your aspect ratio is wrong. Either change capture res or resize the source (you can precisely resize a source using the "Edit Transform" option)
Excellent! That worked. If I rerecord, I'll update the YouTube link!
Thank you!
Oh, I didn't even see that YT link. There seems to be something weird going on, look at the fringe on those magenta invaders. I think you might want to dive into some of those capture settings. (If you have a choice of capture format, choose RGB!) As said above, HDMI capture should give you perfectly sharp edges. Relatedly, to get nearest-neighbor scaling in OBS, you rightclick the source and go "Scaling Filter -> Point". Use "Scaling Filter -> Area" if you can't set the resolution to an integer multiple (for example, when capturing anamorphic sources).
@Wuerfel_21 this is especially helpful, as there will be a lot of video capture in my future for the Quick Bytes, so I need to get my game down on process, configuration, matching frame rates, and everything else you described. It would be a shame to show a P2 video show up with missing frames and we want it to display with the original, highest quality. If you're interested in doing some P2 work and sharing it, I'd be happy to share hardware with you. E-mail me kgracey@parallax.com.
@dgately since you've already got the setup working, could you make a video capture for me of Space Invaders? I'd probably be able to post it by Monday or Tuesday, but it'll be next weekend before I have a functional video capture set up. During the week I can't really do any P2 stuff. . .instead it's purchasing, communication, marketing, and now this very lovely thing I'm looking forward to called CE compliance.
Thanks, Ken
@Ken Gracey
Baggers program outputs both VGA and HDMI so problem solved - use both. Also means you could use capture VGA instead. I would think that you can rotate 90deg when editing the file.
BTW Ken, You will need to do something with the audio as it's not output to HDMI.
If you record both the HDMI and the Audio at the same time and send me the two separate files I can combine them using AVS before you do any editing.
Yep, excellent point. I could capture it via a microphone worst-case, I suppose, and overlay the audio track against the video. Whatever I do, it shall be much better than pointing a cell phone at a display while trying to play a game :)
Ken
Hey Ken,
Just found this while searching. It's not available but there's probably something similar.
Still looking :)
Ken,
I'll try a video capture and post it, on Saturday night.
I was going to suggest an HDMI splitter, but if it is just for the Space Invaders demo then as you said it plays both VGA and HDMI at the same time.
I'll look forward to seeing the video :D
Ken,
Here are 2 captures of Space Invaders being payed on the P2 Edge, recorded via HDMI adapter into and recorded in the OBS App. One video displays just the game screen, while the other includes a still from the Live Forum with Jim Bagley, to fill some of the window. These are currently on YouTube, but are unlisted... I can place the videos in DropBox or send them, if needed...
My game playing skill is not really up to the task of giving the best demo...
dgately
Also, @Ken Gracey, I did send that email some time ago. Did you receive it?