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This isn't really properly a hardware or a software question; it probably involves something of both, and may in fact be impossible without severe do-it-yourself in both areas. I wasn't sure where to put it, but this seems likely to be no worse than any; if it belongs elsewhere, feel free to move it.


Most monitors nowadays have multiple video inputs, so it's relatively easy to hook up multiple computers - or a computer and something else - to the same monitor, and switch display back and forth among them, with no special hardware or software required.

I would like to instead be able to hook things up so that the video stream from the second device is displayed in a window on the desktop of the computer which serves as the first device, optionally scaled (or resolution-adjusted) to full-screen. (And the third device - if any - in a second window, et cetera.) However, I have no idea where to start.

What might it take to be able to do something like that?


(The followup would be trying to also do something similar with sound, multiplexing the audio from an external device into the audio being output through the central computer, with the ability to mute the incoming stream from each external device on the central computer. But that's a secondary consideration, if only because it's easier - and requires less space - to run multiple sets of speakers in parallel than multiple monitors.)

The Wanderer wrote:

I would like to instead be able to hook things up so that the video stream from the second device is displayed in a window on the desktop of the computer which serves as the first device, optionally scaled (or resolution-adjusted) to full-screen. (And the third device - if any - in a second window, et cetera.) However, I have no idea where to start.

What might it take to be able to do something like that?

Special hardware.

http://www.newegg.com/Product/ProductLi ... isNodeId=1

If you have more specifics we could probably make better recommendations.

I figured special hardware would be required, but I wasn't (and still am not) sure it would be enough.

I remember what I've read about video-capture cards as indicating that they are generally used, and in some cases may only be designed, for recording video - i.e., encoding and capturing it to file, or at most encoding and streaming live for remote viewing - rather than displaying it live and realtime (potentially without encoding/decoding first) in a local window. Nothing I've found in a quick search now seems to contradict that. Although I can see in principle how it shouldn't be impossible to do what I want this way, I'd like to ask: can you confirm that it has been and is done, using ordinary video-capture hardware?

As far as specifics goes, the scenario that got me thinking about this was wanting to be able to conveniently set up a gaming console in the same area as my computer, without need for another monitor or the like, and without having to go through annoying gymnastics to switch back and forth between computer and console - ideally, to be able to treat playing the game on the actual console much like playing in an emulator, except for having to use controllers actually connected to the console instead of ones connected to the computer (and/or possibly emulated, e.g. gamepad buttons mapped to keys on a keyboard). However, I'm finding myself also interested in (or at least curious about) the topic more generally.

Also, in case it's relevant and for whatever it's worth, I run Linux. Though that doesn't really bear on being interested in the more general topic.

Do you specifically want the picture inside a window on the desktop computer, or would it be sufficient to have both displays showing up on the monitor in some other way?

Some monitors natively support Picture-in-Picture, and if all you want to do is show two different video inputs at the same time, that should do it.

Every "picture-in-picture" setup I've ever seen has had the second picture small enough that it wouldn't work well for my purposes. Also, with the display in a window I could leave the window on one virtual desktop while I go do something (e.g. look something up) on another, then come back to it, rather than having to have it either "on everywhere" or "off everywhere".

It might be possible to kludge something together that way, but I'm pretty sure that a display in a window would be by far the better solution if it could be made to work properly.

If you don't need smooth real time video/audio playback, you can remote desktop into your other systems.

That won't help for the case which got me thinking about this, though, which is displaying the video output of a gaming console in a window on the central computer. (In which case smooth realtime video would indeed be required, anyway.) I'm specifically thinking about cases where the other device is not necessarily a second computer, at least not as ordinarily thought of.

The Wanderer wrote:

I remember what I've read about video-capture cards as indicating that they are generally used, and in some cases may only be designed, for recording video - i.e., encoding and capturing it to file, or at most encoding and streaming live for remote viewing - rather than displaying it live and realtime (potentially without encoding/decoding first) in a local window. Nothing I've found in a quick search now seems to contradict that. Although I can see in principle how it shouldn't be impossible to do what I want this way, I'd like to ask: can you confirm that it has been and is done, using ordinary video-capture hardware?

Yes.

I have a Hauppauge WinTV-HVR-1600 and an AVerMedia AVerTV HD DVR. Both have bundled windows applications that will allow you to view the stream live on a local window. They both work quite well, though the software can be buggy. It's gotten better over the years though.

The Wanderer wrote:

As far as specifics goes, the scenario that got me thinking about this was wanting to be able to conveniently set up a gaming console in the same area as my computer, without need for another monitor or the like, and without having to go through annoying gymnastics to switch back and forth between computer and console - ideally, to be able to treat playing the game on the actual console much like playing in an emulator, except for having to use controllers actually connected to the console instead of ones connected to the computer (and/or possibly emulated, e.g. gamepad buttons mapped to keys on a keyboard). However, I'm finding myself also interested in (or at least curious about) the topic more generally.

They both work fine for this, and that's why I have both. They're used to record gameplay footage of various different consoles as they are played live through the monitor of the computer system. To be clear, the monitors involved are only hooked up to the PC, the audio/visual output of the console is plugged into the capture card installed in that PC, and the console is directly controlled by its own controllers.

The Wanderer wrote:

Also, in case it's relevant and for whatever it's worth, I run Linux. Though that doesn't really bear on being interested in the more general topic.

Unfortunately, it does.

The hauppauge card has the hardware smarts to fully handle the A/V stream, but I don't think the Avermedia one does. At any rate, last I checked linuxtv.org is viable for the first one, but you're going to have to spin the wheel with wine with the second one. It's possible that the hauppage card is in the mainstream kernel now, but the general problem is that this is something you're definitely going to have to do some independent research on and AverMedia certainly isn't well-supported.

I use Linux too, but this is one of the areas where windows works better. Most of the development behind this sort of thing on the linux side goes towards mythtv, which really isn't the best fit for your intended use case. Maybe things are better these days, but I doubt it. And this is coming from someone who actually uses mythtv for recordings/scheduling. I can't stand as it a video library though (hello Plex!), and I've never even bothered investigating how to handle a stream that's coming from composite/S-video//component (which all recent consoles should be using).

Hopefully, for your sake, someone will correct my ignorance though.

Actually, now you've piqued my interest, darn it! I *may* still have a Hauppauge 1250 lying around that *might* be functional. If I get the time in the next few days I'll install in one my kubuntu boxes and see how far I get. I'll let you know.

Thanks for the information, and for being interested. ^_^ Please keep me posted!

I'll see about investigating Hauppage cards, and Linux video-capture support more in general, in the meantime.

You can look at some of the cards designed for "capturing game footage", but I think even those are going to introduce too much latency to be used for real-time gaming. I understand what you're trying to accomplish, but I don't know that there's any good solution for doing it without bad latency.

Most modern monitors switch between inputs fairly quickly and easily. I actually see switching the audio source as being the bigger hassle, and the one I might consider running though the PC sound card. Of course that means you'd have to jack around with software and such.

The Wanderer wrote:

Thanks for the information, and for being interested. ^_^ Please keep me posted!

I'll see about investigating Hauppage cards, and Linux video-capture support more in general, in the meantime.

If Deanjo doesn't post to this thread, I'd try sending him a PM. From my recollection he may have some experience with video encoding/streaming in Linux that might give you a good solution.

As a more hacky approach, lots of people do screen capturing in Linux using FFMPEG with h.264 encoding that's actually relatively efficient (but can be CPU intensive). If you keep the resolution from getting too high, you might try FFMPEG + network streaming over your LAN to a client like VLC that can receive the stream and display it on the other monitor. This is a view-only solution, however. You are losing the ability to send commands from the remote system to the PC that is generating the video.

The Wanderer wrote:

Thanks for the information, and for being interested. ^_^ Please keep me posted!

I must have given the hauppage 1250 away or something, I can't seem to find it.

The Egg wrote:

You can look at some of the cards designed for "capturing game footage", but I think even those are going to introduce too much latency to be used for real-time gaming. I understand what you're trying to accomplish, but I don't know that there's any good solution for doing it without bad latency.

I may not be as sensitive as a pro-gamer, but it isn't that bad. At all.

I've played Call of Duty online through the avermedia, I couldn't tell the difference.

The Egg wrote:

Most modern monitors switch between inputs fairly quickly and easily. I actually see switching the audio source as being the bigger hassle, and the one I might consider running though the PC sound card. Of course that means you'd have to jack around with software and such.

As someone who has routinely done exactly what the OP is asking one way or another since like 1998, you are vastly over-selling the difficulty.

Glorious wrote:

The Egg wrote:

You can look at some of the cards designed for "capturing game footage", but I think even those are going to introduce too much latency to be used for real-time gaming. I understand what you're trying to accomplish, but I don't know that there's any good solution for doing it without bad latency.

I may not be as sensitive as a pro-gamer, but it isn't that bad. At all.
I've played Call of Duty online through the avermedia, I couldn't tell the difference.

The Egg wrote:

Most modern monitors switch between inputs fairly quickly and easily. I actually see switching the audio source as being the bigger hassle, and the one I might consider running though the PC sound card. Of course that means you'd have to jack around with software and such.

As someone who has routinely done exactly what the OP is asking one way or another since like 1998, you are vastly over-selling the difficulty.

Depends on the person, but you must not be very sensitive to input lag/latency. When I switched from CRTs to LCD about 6 years ago, I noticed the input lag even on one of the fastest TN panels at the time (most notably with emulators where the timing of the games was hard-coded into my brain). I'd just hate to spend $175 on a card, only to find out the lag was too much for me.

I'm not sure exactly what you mean by "overselling", but I regularly connect 2-3 machines to a single monitor (without a KVM switch) when I'm working on other computers. Hitting "input select" and waiting 1-2 seconds really isn't too much of an issue. As I said before, I see switching the audio source to be more of a problem. I suppose if he's willing to spend $175 on a card, that money could instead go towards a cheap receiver which can switch the audio input at the push of a button.

Do you intend to play the console game from your workstation? Or just want to see the output? A web cam should solve latency issues at the expense of quality.

I intend to play the console game sitting at (or, for e.g. Wii games, standing in front of) the desk with the monitor, more or less as if on an emulator, except with the game running on an actual console.


One disadvantage of the "switch video inputs" approach is that it means when the game is visible, I can't do anything else with the computer that's normally connected to the monitor.

With a separate display device for the game console, I'd be able to put down the controller for a moment and switch over to the computer, whether because someone just asked me a question online or because I want to take notes or because I want to look up something about the game or for whatever other reason. Importantly, I'd be able to see the game's current state while interacting with the computer (and vice versa), just by glancing over at the other monitor.

With the game video displayed in a window on the monitor, I could do the same thing, in an only slightly different - and, depending on implementation details, potentially even more convenient - fashion.

With the "switch video inputs" approach, instead of just being able to glance back and forth between the two as fast as my eyes and attention can shift, I'd have to hit the "switch inputs" trigger and wait for the monitor to complete the switch - and quite possibly switch back again only a few seconds later, either to apply the information I'd acquired or to remind myself what information I was looking for. Since the switch itself usually takes at least a second or two in my experience, that's unwieldy and inconvenient, and I'd like to avoid it.


In other words: with separate display devices running simultaneously right next to one another, context switches are cheap. With only one display device, displaying both video sources simultaneously in some way, context swiches are nearly as cheap. With only one display device, displaying only one video source at a time, context switches are expensive.

Given the constraints of my setup, having separate display devices is not practical, so I'm wanting to look into the second option. I've already tried the third enough to confirm that it's not viable for my uses.

How far are we talking about from your computer to your other devices?

Potentially only inches, and certainly no more than two or three feet, at least with my present setup. There are some arrangements I could use that would up that to as much as six to eight feet in some arrangements, but none of them are anything I'm likely to go with.

That's measuring from the side of the computer to the place where the console would sit, not exact connection-point-to-connection-point cable lengths, of course.

You might also consider a dual-monitor setup. If you connect the console to the secondary monitor, you'll still have full functionality of the PC on the primary.

The Egg wrote:

You might also consider a dual-monitor setup. If you connect the console to the secondary monitor, you'll still have full functionality of the PC on the primary.

This. Cheap 1080p monitors with HDMI input are well under 200$ now. Cheaper than some nice TV tuners.

Plus, when you're not using the monitor for the console, you can put other stuff on it.

I personally would run the HDMI or DVI to the PC, and use VGA from the console. Most current gen consoles don't actually run any games at 1080p anyways.

As I already said, given the constraints of my setup, having separate display devices is not practical. (Short of having the game console's display device be in another room, anyway, which would negate most of the benefit and which is my current setup.)

The Wanderer wrote:

As I already said, given the constraints of my setup, having separate display devices is not practical. (Short of having the game console's display device be in another room, anyway, which would negate most of the benefit and which is my current setup.)

Maybe a better desk or a different room? I'm just playing the better-overall versus immediate-need devil's advocate, so feel free to disregard.

It's worth keeping in mind for the long run, but even a desk suitable for that approach might be a problem in the space I have available, and moving it all to a different room is not going to be an available option anytime remotely soon.

The Egg wrote:

Depends on the person, but you must not be very sensitive to input lag/latency. When I switched from CRTs to LCD about 6 years ago, I noticed the input lag even on one of the fastest TN panels at the time (most notably with emulators where the timing of the games was hard-coded into my brain). I'd just hate to spend $175 on a card, only to find out the lag was too much for me

But I'm not terribly insensitive either.

My point is that you are obviously not the average case, and if the OP was anywhere near as sensitive to lag as you evidently are he would already know.

And, as you should know, the speed of the TN panel itself very likely wasn't related to your problem at all. It almost certainly wasn't the pixel driving that was your problem, but rather the display electronics. The more relevant question isn't panel type, but rather things like scaling and connection-type, as both of those can have a tremendous impact on latency even when the display electronics don't suck.

Additionally, It was probably about 10 years ago at this point, and I no longer remember the card involved, but a friend of mine played some version of beatmania IIDX through a capture card without any issue. If latency was always a serious issue with capture cards that simply wouldn't have been possible.

I'll agree that it can be an issue, but I am saying, with actual experience, that I have been doing what he wants to do, on and off, for nearly 15 years now, and I've rarely had a serious issue with input lag. I've probably had something like 6 or 7 different capture cards over the years, so it wasn't just luck either.

The Egg wrote:

I'm not sure exactly what you mean by "overselling", but I regularly connect 2-3 machines to a single monitor (without a KVM switch) when I'm working on other computers. Hitting "input select" and waiting 1-2 seconds really isn't too much of an issue. As I said before, I see switching the audio source to be more of a problem. I suppose if he's willing to spend $175 on a card, that money could instead go towards a cheap receiver which can switch the audio input at the push of a button.

I've done that too, I'm currently running a poor's man's KVM where my dual monitor setup has dvi connections to one computer, VGA to the other, and I switch between the two by pressing monitor buttons and manually unplugging and replugging between two USB cable extenders.

The point is that the OP was already aware of this sort of solution, and he was clearly groping towards a solution that capture cards nicely provide.

You are solving a problem that is only a corollary to a solution he already said he wasn't satisfied with.

Glorious wrote:

And, as you should know, the speed of the TN panel itself very likely wasn't related to your problem at all. It almost certainly wasn't the pixel driving that was your problem, but rather the display electronics. The more relevant question isn't panel type, but rather things like scaling and connection-type, as both of those can have a tremendous impact on latency even when the display electronics don't suck.

I understand; that's not quite how I meant it. I meant that it's a TN panel (which is generally faster than most other types to begin with), and it was known through testing to be one of the best models for input lag (at the time).

Glorious wrote:

Additionally, It was probably about 10 years ago at this point, and I no longer remember the card involved, but a friend of mine played some version of beatmania IIDX through a capture card without any issue. If latency was always a serious issue with capture cards that simply wouldn't have been possible.

I'll agree that it can be an issue, but I am saying, with actual experience, that I have been doing what he wants to do, on and off, for nearly 15 years now, and I've rarely had a serious issue with input lag. I've probably had something like 6 or 7 different capture cards over the years, so it wasn't just luck either.

A capture card may very well work for him, but it's a $175 gamble (or whatever restocking fees would be involved). I'm more or less just trying to alert him to my concerns. Knowing myself, it probably wouldn't work for me.

For whatever it's worth, I'm not likely to play FPS-style games, or any of the other high-end twitch gameplay sorts. The closest to latency-sensitive gameplay I'm likely to come is a platform-action or Zelda-type game, and I think latency is generally less of an issue in those contexts.

(Though when I was trying this once before, using the "switch between monitor inputs" approach, I do recall having difficulty matching combo-sequence timing on Paper Mario... but that might have been due to also using a six-foot-plus controller-cable extender.)

The Egg wrote:

I understand; that's not quite how I meant it. I meant that it's a TN panel (which is generally faster than most other types to begin with), and it was known through testing to be one of the best models for input lag (at the time).

It is definitely annoying that there really isn't much in the way of good data that measures such latency, which I admit is extremely frustrating. We're left with educated guesswork and non-rigorous user testing.

The Egg wrote:

A capture card may very well work for him, but it's a $175 gamble (or whatever restocking fees would be involved). I'm more or less just trying to alert him to my concerns. Knowing myself, it probably wouldn't work for me.

There are some user reviews that try and compare latencies, but again, non-rigorous.

The Wanderer wrote:

(Though when I was trying this once before, using the "switch between monitor inputs" approach, I do recall having difficulty matching combo-sequence timing on Paper Mario... but that might have been due to also using a six-foot-plus controller-cable extender.)

The whole situation is fraught with such perils. It's a shame, but that's just the seemingly never-ending state of things.

If you are worried about latency and further examine the capture card route, you're going to be in jam. Any user-conducted latency testing of any particular model will be almost certainly be non-rigorous and conducted in Windows.

But, if you're not particularly sensitive and the intended games aren't either, the harder question is the linux support.

So long as you have a suitable input device VLC or MPC HC can handle displaying in a window. Just look for the "Open Device" or "Open Stream" option and select your capture card. I used it ages ago with a Radeon 9800 AIW, wanted the capture but didn't want to use ATIs software.

What about a streaming tablet app like Splashtop for the desktop tasks? You can get a tablet (a Nexus 7 will work on the cheap - tho $5 says you already have a tablet that can do this) and stream the desktop to that and just connect the console directly to the monitor. No input lag on the game, so no worries there. Assuming you have a decent network the streaming speeds will be fine and plenty responsive for work tasks - you would just type on your regular keyboard and use your regular mouse. And, if the desktop and the tablet are on the same network, the Splashtop setup is free.

EDIT - realize now you need to do this on Linux... luckily Splashtop works on Linux . Haven't tested it myself tho.

It's a thought, but it would still require me to switch manually from normal computer use to that setup - doable, but more annoying and less convenient than I'd hope for (which is to be able to just power on the console if it's off, launch the viewer program if necessary, and pick up a controller).

Something to keep in mind, but I'm still hopeful about the video-capture-card approach. (Especially since I don't presently have a tablet, though a Nexus is likely in my future somewhere.)