DisplayPort to SVideo/Composite?

Discussion in 'MacBook Pro' started by Timur, Oct 15, 2008.

  1. Timur macrumors 6502a

    Timur

    Joined:
    Oct 14, 2008
    #1
    Hey ladies!

    Does anyone see a possibility to attach an analog TV (SVideo or Composite Cinch) to a new MBP? The only way I can think of is buying a DiplayPort->VGA adapter and then put another VGA->TV-Output adapter in between. Quite awkward.

    Any input welcome.
     
  2. donbenjy macrumors 6502

    Joined:
    Oct 15, 2008
    #2
    I can't help you, but I was wondering about how "daisy-chaining" would work...loads of my friends have old MBPs, and it'd be so much easier to only have to buy the displayport>DVI, then use their existing adaptors! I asked when I bought my Pro today, but they didn't seem to know, and it was really busy, so I didn't wanna get them to try it out for me! Plus its like £20, so I don't wanna be spending that much if it won't work! It would also mean that I could take that, plus my DVI>VGA adaptor from my old mini around for projectors!

    The displayport thing is ok, but it's such a pain when hardly anyone uses it yet! Oh well - I wonder just how much Apple can make from their proprietary connectors!
     
  3. danse macrumors newbie

    Joined:
    Feb 10, 2004
    #3
    Before suggesting that Apple is pushing proprietary connectors, it might do good to research a bit; DisplayPort is a new emerging standard put forth by VESA and is royalty-free and license-free. Apple, like its push with USB, is adopting a new standard in an effort to make it mainstream.

    Seems like you can daisy-chain it (as DisplayPort specs list support for legacy signal streams) but I've yet to see someone try linking DP - DVI, and DVI - Composite adapters together.
     
  4. mkrishnan Moderator emeritus

    mkrishnan

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    Jan 9, 2004
    Location:
    Grand Rapids, MI, USA
    #4
    Do some of the MBPs use the DisplayPort? I thought they all use Mini DisplayPort. The problem is that, while DP is an open standard, MDP is not, and as far as I know, Apple has not published detailed specifications on how the MDP works / whether it supports all DP specs, nor has the hacker community fully reverse engineered it or tested it out.
     
  5. donbenjy macrumors 6502

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    Oct 15, 2008
    #5
    Before you go jumping down people's throats, I suggest you actually research stuff properly. Kindly show me, if the MDP isn't proprietary, any other product that uses it.

    As mkrishnan pointed out; Apple haven't even published full specs, so how can there be any other manufacturers using it?

    I'm sure that the MDP technology allows for daisychaining - I'd be shocked if they didn't, but that isn't the point. What I suggested was that Apple would milk this. and to clarify: They are.


    [​IMG]

    The Apple MDP>DVI adaptor does not allow daisy-chaining, because the analogue pins have been removed (the 4 arranged in a square on the left). It's just a DVI-D (single link). Can you offer me any reason why they would do this, other than to stop users from buying not one, but two adaptors?

    I haven't seen the dual-link DVI adaptor, but as that's 3 times the cost of the others, there would be little point in buying that unless you also had a dual-link display as well.

    Am I happy with my new MBP? yes. Did Apple screw us on the ports? yes.

    Stop being such a fanboy, and realise that, no matter what the reasoning behind it, Apple have left us seriously wanting with the ports.
     
  6. 3247 macrumors regular

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    Feb 9, 2008
    Location:
    Germany
    #6
    On a German webform, someone cited an email message from VESA indicating that MDP will be part of DisplayPort 1.2 (current version 1.1a): http://www.macuser.de/forum/showpost.php?p=4587698&postcount=83 (Don't worry, the interesting part is in English.)
     
  7. NewMacbookPlz macrumors 68040

    NewMacbookPlz

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    Sep 28, 2008
    #7
    They use DVI-D because DisplayPort only carries a digital signal. The VGA dongle apple sells must have a DAC built in or something.
    http://www.datapro.net/techinfo/displayport_info.html
     
  8. mkrishnan Moderator emeritus

    mkrishnan

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    Jan 9, 2004
    Location:
    Grand Rapids, MI, USA
    #8
    This seems pretty unlikely, simply based on the size of the Apple adapter (in comparison to all the existing video DACs on the market) ... I think that again, while DP does not support the analog signal, Apple has never really said their MDP's are equivalent to DP's. I think there being a DAC in the adapter is a major stretch -- it's much more likely they've commandeered some pins somewhere on the DP that they're not using to send through the analog signal.
     
  9. cal6n macrumors 68000

    cal6n

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    Jul 25, 2004
    Location:
    Gloucester, UK
    #9
    DisplayPort does allow for analog signal conversion.

    This:

    is from the address mapping from version 1.1a of the VESA DisplayPort standard (p.122).

    I think it's very good news that Mini DispalyPort will be part of the standard. That means that 3rd party adapters will eventually fill our needs.
     
  10. Lornholio macrumors newbie

    Joined:
    Sep 19, 2008
    #10
    Just adding this into this old thread rather than creating a new one...

    I'm in the same position as the thread creator, I need to get an s-video or composite connection to link my MB to TV. So as has been said on a few threads you need to go MiniDisplayport > VGA then VGA > video. Apple store UK (and US for that matter) is not showing any VGA video adapters. Will cheap eBay ones work (see links below) as direct replacements or is there something fancy going on inside that little white box on the genuine Apple ones?

    The unsuitable DVI one I bought is labeled PAL, does that really matter? My old Canadian Dell PC displayed fine through S-video on my UK/PAL TV.

    This listing does say "Please check your PC & Video Card manual or manufacturer to make sure that your VGA card has TV-Out function capability through the VGA".

    And this one similarly: "Your VGA card must support TV out directly through VGA port function".

    [​IMG]
     
  11. mkrishnan Moderator emeritus

    mkrishnan

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    Jan 9, 2004
    Location:
    Grand Rapids, MI, USA
    #11
    There obviously are some different opinions on this. I'll continue my statement that I find it extremely unlikely that any of the Apple plug adapters have a DAC inside them.

    So then, the question isn't whether any old VGA -> S-Vid adapter would work. Yes, any one should work, rather than just one from Apple.

    The question is whether the VGA side of the MDP actually carries a composite signal through to the VGA side. The VGA spec specifies this as an option, but as you know, historically, not all VGA devices output composite. Apple obviously could have output composite, but then they could have output DVI-I also, and yet they chose not to.

    I dunno what to tell you except that someone has to get the hardware, try it, and confirm whether or not it works.
     
  12. Lornholio macrumors newbie

    Joined:
    Sep 19, 2008
    #12
    OK, I've bought one of the eBay ones, only £2 so no big deal. I'll post the results. I'll need to visit the Apple store to get a MDP > VGA sometime this week first though.
     
  13. donbenjy macrumors 6502

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    Oct 15, 2008
    #13
    How you do you know they don't output DVI-I? Just because the adaptor doesn't have the right pin-set, it doesn't mean that the signal isn't present. Surely the analogue signal is present at the port regardless of whether the pins are used, so if there was a 3rd party DVI-I connector, that would work definitely.

    Also, why would you need a DAC to go from VGA (analogue) to composite/S(analogue)? The question is whether the VGA spec allows composite through.
     
  14. mkrishnan Moderator emeritus

    mkrishnan

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    Jan 9, 2004
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    #14
    The VGA spec definitely allows composite. Google it.

    As for the DVI-I, I meant that the MDP->DVI adapter does not provide DVI-I. Several people have tried (and failed) to use DVI-VGA adapters daisy-chained on it, which would seem to be a fairly compelling demonstration of this. Of course, the analog signal is present on the MDP.If someone made a 3rd party MDP->DVI-I adapter, of course it would work.
     
  15. Timur thread starter macrumors 6502a

    Timur

    Joined:
    Oct 14, 2008
    #15
    If anyone finds a working solution for the composite/shvs problem, please report back.

    As far as the DVI-I/D question is concerned a little internet search reveals that. Neither the DisplayPort nor the MDP->VGA adapters do any kind of conversion!

    Both the DVI and the VGA signal are natively created by the graphic-chip and then just send over the (Midi)DisplayPort where a simple connector rewires them to DVI and/or VGA (some voltage conversion may be required though).

    So in theory it should be possible to build a single MDP to DVI-I/VGA adapter, but there may be one reason why this doesn't work in practice. I don't know wether the adaptor or the screen connected to it is the one who tells the graphic-chip which signal to send. If it's the adaptor then it makes sense to build single adaptors.

    Maybe it isn't even possible to send two separate signals (DVI-I = DVI-D + VGA) over one DisplayPort because of that the adaptor has to tell the chip which signal to send. I didn't dive that deep into the subject.
     
  16. Lornholio macrumors newbie

    Joined:
    Sep 19, 2008
    #16
    So I got my Mini DisplayPort > VGA adapter and a cheap eBay VGA > S-video/composite adapter. Connected up, the Macbook recognises there is another display connected ("VGA display" or something similar) but the picture on the TV is full of static/wavy lines/etc for all display settings. The lowest disaplay setting (640x???, 59Hz) shows some stretched out windows repeated across the TV screen in black and white. Results are the same with S-video and composite.

    I know from my laptop PC that my TV can take a 640 or 800-wide input (Windows detected it as a television). So I suspect it's a setting on the Macbook that's not right. I am in the UK so could PAL be a reason? And the "VGA display" lowest setting was 59Hz - aren't TVs 24 or 25Hz?

    I did find a post somewhere online from someone with a similar problem who replaced their eBay adapter with an Apple video adapter and it worked right away. But I can't see any Apple ones online, only DVI, Mini DVI or Mini VGA to video. What's needed is VGA to S-video/Composite
     
  17. cornelius1 macrumors member

    Joined:
    Jul 12, 2008
    #17
    The MDP->VGA and the cheap VGA->S-video adaptor combination doesn't work. The working solution is described in this thread.
     
  18. Lornholio macrumors newbie

    Joined:
    Sep 19, 2008
    #18
    The only solution is an external powered conversion box? Pathetic, Apple. I'm glad I still have my PC for now. Are there plans for a MDP to video adapter or does Apple not think it'll sell?
     
  19. 3247 macrumors regular

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    Feb 9, 2008
    Location:
    Germany
    #19
    The spec (DisplayPort Interoperability Guideline v1.1) does define adaptors for DVI-D and HDMI (which are quite similar) but not for VGA. Mini-DisplayPort is not present, either, and supposed to appear in v1.2. Maybe the new version will also contain guidelines for making triple-mode devices that also support VGA and/or S-Video/component video.
     
  20. GizmoGimps macrumors newbie

    Joined:
    Nov 24, 2008
    #20
    I have successfully used a DVI to S-Video Adapter to hook my G5 PowerMac to an analog TV by going through to RCA input on my VCR.
    It worked fine as my second monitor for months, and then I unhooked/re-hooked up my computer and have not been able to get my computer to detect the DVI to S-Video display since!!
    Its driving me nuts, especially because it has worked previously with all the same stuff.
    Any tips on on getting my G5 to detect my second display would be great!

    Thanks
     

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