Xbox one to 2010 iMac target display mode

DominoD7

macrumors newbie
Original poster
Nov 17, 2011
3
0
So hopefully somebody with more technical knowledge can explain if this is possible....

I noticed the latest Xbox One update can now output 2560 x1440 resolution....

I noticed target display mode on mid-2010 iMac supports input 2560 x 1440 resolution.....

I bought a hdmi to Mini DisplayPort cable and connect the 2 together and...... nothing.

I do already have it working via the belkin AV360 adapter which converts to 720p but was curious if the 1440p option would work.

Anyone know where the problem could be?
Thanks for your time and knowledge.

D7
 

DominoD7

macrumors newbie
Original poster
Nov 17, 2011
3
0
Which HDMI and Mini Display Port specs are the adapter rated for?
I see no reason this shouldn't work with the right cabling
Not sure but i will investigate. It was a amazon cheapie.

I did read somewhere the xobox will only offer 1440 resolution if auto-detected by a compatable monitor which the iMac may not be.

Unfortunately I can’t test it by connecting to another 1440 monitor first.
[doublepost=1527018620][/doublepost]Casperes- you may be onto something. I just noticed the cable says full HD which I understand is lower than 2560 x 1440?
 

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jerwin

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Jun 13, 2015
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converting display port into hdmi is trivial.
converting hdmi into display port is hard.

directionality matters.

https://www.macworld.com/article/1151256/kanexxd.html
[doublepost=1527022728][/doublepost]the nitty gritty:

https://en.wikipedia.org/wiki/DisplayPort#DisplayPort_Dual-Mode_(DP++)

  • Unidirectional — Although the dual-mode standard specifies a method for DisplayPort sources to output DVI/HDMI signals using simple passive adapters, there is no counterpart standard to give DisplayPort displays the ability to receive DVI/HDMI input signals through passive adapters. As a result, DisplayPort displays can only receive native DisplayPort signals; any DVI or HDMI input signals must be converted to the DisplayPort format with an active conversion device. DVI and HDMI sources cannot be connected to DisplayPort displays using passive adapters.
  • Single-link DVI only — Since DisplayPort dual-mode operates by using the pins of the DisplayPort connector to send DVI/HDMI signals, the 20-pin DisplayPort connector can only produce a single-link DVI signal (which uses 19 pins). A dual-link DVI signal uses 25 pins, and is therefore impossible to transmit natively from a DisplayPort connector through a passive adapter. Dual-link DVI signals can only be produced by converting from native DisplayPort output signals with an active conversion device.
  • Unavailable on USB-C — The DisplayPort Alternate Mode specification for sending DisplayPort signals over a USB-C cable does not include support for the dual-mode protocol. As a result, DP-to-DVI and DP-to-HDMI passive adapters do not function when chained from a USB-C to DP adapter.
 
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casperes1996

macrumors 603
Jan 26, 2014
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Horsens, Denmark
Casperes- you may be onto something. I just noticed the cable says full HD which I understand is lower than 2560 x 1440?
Some terminology:

HD Ready: 1280x720 (720p)
FullHD: 1920x1080 (1080p)
QHD: 2560x1440 (1440p)
UHD: 3840x2160 (2160p)

These sometimes go by other, incorrect names, like 4k and 2.5k. The terms are also sometimes used for very similar resolutions, like 1920x1200 sometimes being called FullHD, even though the FullHD spec technically only specifies 16:9, whereas the 1920x1200 resolution is 16:10. As far as I know anyway - the spec may be bigger than I know actually. Regardless, yes; 2560x1440 is more than FullHD.

I did read somewhere the xobox will only offer 1440 resolution if auto-detected by a compatable monitor which the iMac may not be.
So the way auto-detection of resolutions and other monitor details works, is a bit tricky. The reason again being that different specs have different methods of doing this, and the iMac does inform Display Port clients about itself, using the Display Port standard (EDID - Extended Display Identification Data). Newer DisplayPort standards also support another information table, known as DisplayID. I don't know what HDMI uses to transfer its data stream for a monitor's capabilities. EDID is a standard, so it may very well be that it just uses that too, but it's a standard made by the VESA group, who also are behind DisplayPort, so the group behind HDMI may have their own separate solution. An adapter may be able to convert this data stream as well, if it is not able to just carry it on. It does seem like this would be necessary to get 1440p though. Even then though, Display Port through an adapter should at least give you 1080p no issues, since I assume that's what the Xbox One defaults to if it gets no monitor capability details.

converting display port into hdmi is trivial.
converting hdmi into display port is hard.

directionality matters.

https://www.macworld.com/article/1151256/kanexxd.html
I'm only really quoting this to emphasise it. Display Port is made to be compatible with other standards, but how trivial the conversion is, isn't a concern for the VESA - just that it's doable.
[doublepost=1527023962][/doublepost]Just something you might want to read about EDID
https://www.extron.com/company/article.aspx?id=uedid&version=print

As well as a product guaranteeing to send the EDID information
https://www.extron.com/product/product.aspx?id=hdp1014k&s=4#desc

It doesn't sound like it's something of an expected standard that adapters will send the EDID data though. They say that their adapter asks the display about it's EDID data, stores it inside the adapter, and sends the signal to the source on power-up, making it sound like it's not passed through the cables, but has to be actively passed through the adapter.
 

redheeler

macrumors 604
Oct 17, 2014
7,659
7,501
Exactly this:
converting display port into hdmi is trivial.
converting hdmi into display port is hard.

directionality matters.

https://www.macworld.com/article/1151256/kanexxd.html
[doublepost=1527022728][/doublepost]the nitty gritty:

https://en.wikipedia.org/wiki/DisplayPort#DisplayPort_Dual-Mode_(DP++)
No passive adapter or cable will do it, you absolutely need an HDMI to DisplayPort or DVI to DisplayPort converter which converts the HDMI signal into a DisplayPort signal in real-time.

Here is how I used my 2010 iMac as a display for an older Mac with dual-link DVI (and no DisplayPort) at native res; however, I don't think you could get any higher than 720p (the highest it will go with single-link DVI) to work with an HDMI signal.
 

macduke

macrumors G4
Jun 27, 2007
11,032
14,846
Central U.S.
I can't even get my MacBook Pro to go to an older iMac from this era we have lying around at work so good luck with an Xbox, lol.
 

EugW

macrumors G3
Jun 18, 2017
8,836
6,154
I can't even get my MacBook Pro to go to an older iMac from this era we have lying around at work so good luck with an Xbox, lol.
What are you using?

I have no problem using my 2010 2560x1440 27" iMac as an external monitor for my MacBook 2017 or my iMac 2017.

You need the proper adapters/dongles though. Lots of incompatibilities with current Macs' USB-C ports.
 

macduke

macrumors G4
Jun 27, 2007
11,032
14,846
Central U.S.
What are you using?

I have no problem using my 2010 2560x1440 27" iMac as an external monitor for my MacBook 2017 or my iMac 2017.

You need the proper adapters/dongles though. Lots of incompatibilities with current Macs' USB-C ports.
Mini DisplayPort adapter -> DVI cable -> Mini DisplayPort adapter. I started working one day a week in another office to help them with a project and get training on their new development frameworks and they don't have an external monitor for me aside from some old iMacs laying around and IDK how to get it to work. I need to do some more in-depth googling.
 

EugW

macrumors G3
Jun 18, 2017
8,836
6,154
Mini DisplayPort adapter -> DVI cable -> Mini DisplayPort adapter. I started working one day a week in another office to help them with a project and get training on their new development frameworks and they don't have an external monitor for me aside from some old iMacs laying around and IDK how to get it to work. I need to do some more in-depth googling.
I don't think that would work.

It sounds like all you need is a Mini DisplayPort cable. They're something like $6 at Monoprice.

https://support.apple.com/en-ca/HT204592

In my case I use a USB-C to Mini DisplayPort adapter, attached to a Mini DisplayPort cable, although it's also possible to just get a direct USB-C to Mini DisplayPort cable too.
 
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