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Output to DVI/HDMI and s-video/composite at the same time?

Discussion in 'Computer Systems' started by jon_c0, Oct 13, 2006.

  1. jon_c0

    jon_c0 Member

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    I want a home cinema PC setup where I can drive the same image to both an LCD display in my lounge (DVI/HDMI) and a smaller LCD display in my kitchen (s-video/composite) via a long cable.

    Are graphics cards available that can drive both an LCD display using DVI/HDMI and an additional display by either s-video (ideally) or composite at the same time? Are there any obvious "gotchas" in this?
  2. pmc

    pmc Member

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    Most graphics cards on the market wil do this. Just check the outputs, most will have a DVI and a S-Video out. It's a very common arrangement. Personally I find ATI better than Nvidia for handling dual displays like this.
  3. motile rod 2

    motile rod 2 Member

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    Yes, they all do this.
  4. jon_c0

    jon_c0 Member

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    Ah...fantastic, thanks chaps. I've been a bit detached from anything that could be consider cutting-edge with regards to current spec graphics cards, and hence just wanted to make sure that simultaneous use of both digital and analog outputs was a commonly supported thing.

    Actually...related to this. Assuming that the DVI output is set at a resolution to match the LCD TV in my lounge, will the s-video output typically be sorted to display a "normal" full-screen picture for the additional TV? My only experience of this sort of dual display stuff in the past is with an ATI card supporting TV out - in order to get a non-"portal" output to the TV, it was necessary to have both outputs set at 800x600, which obviously won't be what I'll be after...
  5. warbie

    warbie Member

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    I'd be interested to know the answer to this too.
  6. jon_c0

    jon_c0 Member

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    Could anyone confirm whether it's feasible to use s-video and DVI output at the same time from common graphics cards and, most importantly, whether the s-video output is appropriately scaled to give a "normal" full output for a TV regardless of the resolution set for the DVI? I'm wondering whether this simultaneous use, with the TV-out producing an appropriate version of the DVI-out, is a bit of a niche case...
  7. pmc

    pmc Member

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    Certainly you can output both at the same time. What happens with the scaling will depend on the card and your settings, but it's certainly possible to do it.

    I have an ATI 6200, a pretty low spec card by todays standards but it's fanless which is the most important thing for me. It has DVI and S-Video out. I set my desktop resolution to 1280x720, i.e. 720p. My primary display is a projector and I connect that with DVI. My secondary is a CRT TV and I connect that with S-Video. I then clone the display onto the secondary. With ATI this causes the desktop to pan on the secondary display. This means that I can only see around half the desktop at a time and have to pan the display about to see other parts of the desktop. However when I play video it swtiches to full screen. So I get a full screen video display on my secondary no problem.

    This is pretty standard behaviour I think. Higher spec cards may be able to output two completely different desktop resolutions at the same time but I am only interested in using the secondary for video playback so it's fine.

    When you are looking at a card check that it has has both DVI and S-Video out and check that it supports cloned displays.
  8. jon_c0

    jon_c0 Member

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    Thanks PMC - I understand now. From your description it's "Clone display" that's the bit of terminology that I'm missing, and from what you've said I now know not what to check out in the graphics cards I'll be looking at.

    Cheers!
  9. jon_c0

    jon_c0 Member

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    I'm resurrecting this older thread as I've now sourced a case and so am looking for some graphics cards recommendations to fit my "dual DVI/HDMI and s-video output" requirements. My system will be purely run as a HTPC, and with the new TV I'm planning on buying I'm just looking for 1080p over DVI/HDMI and a simultaneous output of the same content via s-video to feed a second TV in the kitchen (as per the thread above). Ideally I want something that works with both TVs solidly after being configured i.e. I don't want to have to fiddle with the settings after initial setup to have both displays working reliably. The boxes I do have to tick are as follows:

    PCIe
    Low-profile
    Passively cooled (or, at least, quietly cooled).
    S-Video output
    DVI or HDMI
    Able to output the same display simultaneously over S-Video and DVI/HDMI.

    Any recommendations/personal experiences with this particular kind of "dual output" setup?
  10. jon_c0

    jon_c0 Member

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    Both of the following were given in response to a somebody else's request for low-profile PCIe cards:

    XFX GeForce 7300LE
    Sapphire RADEON X1300

    These look like they fit the bill from a naked "supported video output" perspective, but what I'm not clear on is if they can transparently drive both DVI and s-video with the same output at the appropriate resolutions...that would be the key thing for me. Looking at the GeForce card...IIUC this supports nVidia's nView stuff which seems to include both "Dualview" and "Clone mode" from the listed support. Looking at the video presentation, and as suggested earlier in this thread, "Clone mode" seems to be the boy... Looking at the nView documentation, it seems that you can set different resolutions in clone mode for DVI and s-video/TV output, but great emphasis is placed on the advantages of the "Virtual desktop", where the display with the lower resolution has a pan and scan outlook of the same output being displayed on the higher resolutions display. I guess this is exactly what I don't want...but it's not 100% clear to me whether this is always what happens, or whether it's possible to drive both displays to provide full screen pictures (at least as much as possible) without pan and scan. Or I am misunderstanding what's possible here?

    Anyone any experience of the above or any other good alternatives/suggestions?
  11. jon_c0

    jon_c0 Member

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    I'll apologise now as I'm just responding to my own posts :) . However, I guess it might be useful to others to log what I've found out so far (at least it is for me) and I hope someone more knowledgeable than I drops by soon with some concrete views along the lines of "Nooo...you've the wrong end of the stick there". I guess I'm kind of surprised that "identical dual display output" isn't more of an issue, especially with HTPCs where driving two displays in two different locations would seem to be a useful thing to do.

    Now - from what I can gather the simultaneous display of something being output via DVI at a HD resolution for an LCD TV/monitor and via s-video at a lower resolution for a TV isn't something that NVidia cards do particularly well. At least, from what I can gather, their "clone display" really is just that - a clone, that will end up giving you only a pan and scan window on the lower resolution display of what's full screen on the higher resolution display. Can anyone confirm/deny this because, if so, I can at least restrict the field by striking NVidia cards off my list...

    Now...ATI cards seem to further support a "Theater Mode" option as part of their "Clone Mode", that really can give you an identical display via both higher resolution DVI and lower resolution s-video, including streaming video. What I'm still not clear on from my digging about so far is whether things like video playback really are supported in this "dual mode" and with a reasonable quality in both cases. I'm also not clear on how fiddly this all is. Ideally, from an end user perspective, I just want an identical display from both outputs; DVI needs to be good and smooth 1080p on my main lounge display, s-video of the same content just needs to be adequate for a kitchen LCD. Anyone with experience of ATI's "Theater Mode" that can comment?

    Ta.
  12. Nick_W

    Nick_W Member

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    Both my Nvidia cards (in different PCs) are able to output 1280x720 over S-Video and DVI at the same time (clone mode).

    So yes, I can confirm that it works. ATI cards are unable to do this, which is why you shouldn't buy one if that's what you want to do.

    Let me know if you need more info.

    HTH,

    Nick.
  13. jon_c0

    jon_c0 Member

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    Do you have full screen display on both of your outputs, or does the s-video output provide a "pan and scan" Window onto what's being displayed over your DVI output? If you have full content on s-video, and the same occurs when you're driving the DVI at 1080p, then I've got the wrong end of the stick and it looks like a single NVidia card might meet my needs.. If not, however, what I'm after is a simultaneous full-screen display of all content on each output, with no pan and scan. My understanding is that NVidia cards in "Clone Mode" operate in the same way as outlined in pmc's posting above. The reason that his secondary display jumps from "pan and scan" to 'proper' full-screen when playing a video is because of ATI's Theater Mode, I would guess, and the fact it can supply just the video overlay at the correct resolution, if not everything else. This isn't suitable for me either as I want everything full-screen on each output - the full Desktop, running applications, DVDs etc.
  14. Nick_W

    Nick_W Member

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    Yes, full screen, no pan-and-scan. You can get most resolutions via s-video with nvidia cards, it's just a matter of using advanced timings.

    The nvidia card is what you need. ATI cannot do this properly (Theatre mode is a kludge).

    Regards,

    Nick.
  15. jon_c0

    jon_c0 Member

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    Excellent - thanks, that's good news.

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