Monday, December 3, 2012

Trouble and success with mini DisplayPort

On Saturday and Sunday I continued watching video through the mini DisplayPort using the 8 foot Belkin HDMI adapter.  It worked OK, but the images looked very blurry, up close you could see obvious jagged-edge type artifacts.  It seemed like I could adjust UP the sharpness control on my Sony XBR-960 TV and Samsung LCD to make it better, similar to what has been claimed on web.

This is curious because what what sharpness controls do is actually distort the picture by boosting high video frequencies, similar to the use of the Treble control on old hifi equipment.  This doesn't actually increase true resolution, it lowers it actually, but might have an objectively beneficial effect if the source has excessive high video frequency rolloff.  Has Apple somehow pre-compensated for old analog sets when it makes connections at 480i. since such sets were frequently set with high "sharpness" control settings?  Or did they just use an especially lousy 480i video codec?

But another question was why, in this setup, I was being restricted to 480i.  There were no copying devices hooked up to the system.  HDMI goes first to a 5 way switch which is about 2 years old.  Then it goes to a 4 way splitter that is about 5 years old.  All of this handles 1080i perfectly, in fact that's what it often does.  In fact it even handles 1080p, except my 2005 CRT TV does not.

Somehow, when DisplayPort sees this HDMI switch, it refuses to engage any resolution higher than 480i.  No other devices have had that problem.  I tried re-hooking, different inputs, and powering up and powering down, and fiddling with the Display preferences, but DisplayPort has decided that you have a 480i device, you only have NTSC and PAL resolutions to choose from.

I disconnected the computer, keyboard, display, mouse, and cables and took them to the bedroom and hooked directly to my 1080p Samsung TV.  THEN the display port had no problem doing 1080i or 1080p, directly to my TV.  I tried both the Belkin and Rocketfish adapters, and they worked identically in this setup.  I normally use the Rocketfish Mini DisplayPort to HDMI adapter in the bedroom with my bedroom macbook pro.

So I brought the computer and stuff back to the living room, and tried using the Rocketfish adapter.  Once again I could only get 480i.  Since the two adapters behaved identically, I think the defective "intelligence" is actually in the DisplayPort itself.  After going back to the Belden adapter, and after lots more fiddling, I was stuck with no visible output just as I had been on Thursday night.  In the worst cases, the Display preferences don't even show a second display connected.

One of my theories is that mini DisplayPort is paranoid.  It agressively downrezes to 480i if it sees anything "fishy" on the output as part of it's copy-prevention protocol which goes above and beyond HDCP.  Even just an HDMI switch can engage this feature.  Apple does says that you can use the DisplayPort output with one adapter, and no more.  A switch is not an adapter, but still enough to give DisplayPort fits.  (This theory is a bit inconsistent with my later successes, read on.  Perhaps the DisplayPort is paranoid about the wrong things.)

It's also possible that something on my video network is reporting back it's capabilities incorrectly.  But since all my other 1080i devices on the switch work fine in 1080i, I think I can fairly say that the mini DisplayPort is not acting as switch (or splitter) friendly as true HDMI components.  Thus I am not surprised at all that Apple doesn't make an actual HDMI adapter.  They may know their interface is bugged, and it may be bugged deliberately.

So this was not looking well for connecting miniDispayPort to my Sony RDR-HX900 video recorder.  That connection through the Sony was the way I used to view the computer output, as it also conveniently switches in some other 480i components, with all of them, including video stored on the Sony itself, getting converted to 1080i with my HDHO adapter on the output.

But in fact, I hooked the mini DisplayPort to a miniDisplayPort to Component Video adapter (interestingly no longer advertised on the Monoprice website, but I found it searching on Amazon) and it worked fine.  I got clear 480i direct into my Sony.  I could select 480p, but then the Sony output went dark.  I checked the Sony manual and found that while the Sony allows 480p output, it only allows 480i input.  So this is the best I could do with any adapter.  Actually, the display preferences in this case let me select up to 1080p...the Monoprice adapter works with 1080p even if my old Sony does not.  I was also able to play back videos I have downloaded from commercial erotic websites also, with no problem.  I did not try playing DVD...I have little doubt that would not work.

And most strangely, the video even looked better this way.  The jagged edges were gone.  It's possible the image doesn't have any more resolution, in fact it might have less, but I think it looks better somehow (no side by side comparison possible now).  Possibly it's because the Sony decodes 480i better than most things.  Then the Sony output goes through an Anchor Bay DVDO to generate DVI, which gets adapted to 1080i into my HDMI switch.

So after this weekend, I cannot claim not to be a happy camper.  For years I resisted upgrading my Mac fearing that I would loose my old video setup.  Now I have my old video setup back, working fine*, and it looks about as good as before if not better, driven by a computer that doesn't strain (and often crash) under the load of YouTube video like my old one did.  Technically, my old Powerbook setup used S-Video and this new one uses Component, so it could be slightly better even, and I think it does look better now, despite the earlier lousy looking 480i on HDMI.

(*The hard drive in the Sony RDR-HX900 needs replacing.  The old one keeps old recordings, but won't keep new ones.  I bought a replacement harddrive a few months ago, didn't replace it when it seemed like the old harddrive was working again, but then I found it would not keep new recordings.)

It would still be good to have a direct Mac connection to my video system through HDMI at a higher resolution than 480i, then I could watch web videos at higher resolutions than 480i.  I never had that capability before, but I can see it would be nice.  Though I fear the limitation may be with the Mac DisplayPort, my positive experince with a component video adapter bodes well that a possibility still exists.  Perhaps there is some kind of communication problem with my video network that the Mac is sensitive to, but could be fixed with a gadget like the one sold by Geffen which forces a particular description of display capabilities onto the HDMI line.

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