[opendtv] Re: HDMI attracts three challengers

Thanks Mark,

 

I would like to respond below.

 

Also how do I get to OpenDTV list?

 

>>> 

Couple of issues raised by Dan:

 

Conversion form DVI to HDMI. The TMDS video structure of DVI and HDMI is the same. DVI is RGB, HDMI can be RGB or YCbCr but most often YCbCr on all consumer products. DVI does not carry copy protection (HDCP) and Audio in the blanking interval. The DVI and HDMI EDID structures are slightly different.  HDMI EDID has more data and additional data about Audio. The copy protection HDCP is not part of EDID even though same I2C lines are used. EDID is an EPROM attached to I2C lines and is read by a source in order to understand display resolution and audio capabilities. One more important difference: DVI source may have all Video or VESA resolutions. HDMI is most likely to work in 480i, 480p, 720p, 1080i, 1080p/24,1080p60.

 

So converting I would use DVI TMDS data as is making sure that display is capable to receive RGB and to make sure the DVI resolution is accepted by the display. The DVI source is usually OK without seeing any EDID. No HDCP will be understood either. So in DVI to HDMI conversion best thing is to connect TMDS lines only (4 twisted pairs) and hot plug and not to use I2C, CEC or any other HDMI additional lines.

 

HDMI to DVI. If HDMI is copy protected as most consumer sources are – this is illegal.

 

HDMI to HD-SDI -  same issue.

 

HDMI switching and distribution: Yes HDMI is designed basically for consumer equipment interconnect. For distribution you need to deal with EDID either by selecting preferred EDID from one of the display or substituting that EDID by distribution amplifier default EDID. There are products on the market that enable EDID substitution. The HDCP key management is also a touchy issue. The best most reliable way is to have independent authentication of each input and output of the distribution amplifier. There are products which allow that as well. Once EDID and HDCP authentication is under direct control of the installer HDMI becomes far more manageable for professional and commercial applications.

 

Best Regards,

 

Mike Tsinberg
Key Digital Systems
Office: 914-667-9700 ext. 235
Fax: 914-668-8666
Cell: 646-391-7537
Skype: digimike
email: mike@xxxxxxxxxxxxxx
web: www.keydigital.com

I've just completed an install with HDMI technologies, and I believe the state of digital connections is in serious trouble.  We (not me but a bunch of engineers specializing in AV technologies) tried doing a complete digital path with DVI from the computers, HDMI from the Blu-Ray players, DVI from the document camera, etc. to the projector for an auditorium.  This requires converting everything to HDMI to get the Blu-Ray player to work.  We had to really mess with the design to get things to work (in fact we didn't with DVI as I'll explain later).

The first problem is the distance limitations.  Then there is constant converting of DVI to HDMI and back (HD-SDI, too).  But the worst is trying to get the EDID to work.  It seems that most of the electronics out there do not properly handle the keys.  Naturally, there are specifications that provide requirements to properly handle things (with up to 40 keys shifting around), but it turns out that most electronics do not handle them properly, in fact sometimes not at all or at least enough of them.  HDMI works when you have one player plugged into one monitor, but as soon as one starts using switches and routers, getting pictures is very difficult.  I must disagree with the quote:


" 'These technologies do start at the professional level, but it's such an
easy technology to use that people won't hesitate linking their Blu-Ray
player to a digital TV over HDMI' for applications like whole-home video
recording, said Rob Tobias, director of market development for Silicon
Image."

In our installation, there were no recording devices, only sources (camera, computer display, Blu-ray) and monitors (projector and LCDs).

After doing some research, we discovered there are some technologies on the horizon to deal with the issue.  For instance, Crestron will have an image processor with card slots and proprietary processing to handle the EDID keys.  The results will be active switching with key handling.  Active (hot switching) will not currently work with EDID, at least not reasonable enough to use in production.

So what did we do?  We went back to RGBHV analog signals for almost everything and are routing and processing them instead of digital.  Unfortunately, there are some distortions due to processing but at least the picture is there.  

We do still use some digital: in order to get 1080p from the Blu-ray through the HDMI to the projector, we must turn on or turn off certain pieces of equipment.  We do that when we need the pure path for a Blu-ray.

By the way, the RGBHV outputs on our Panasonic Blu-ray players do still put out a 720p signal.  I understand there is a moratorium until 2012 on scaling the analog signal back to 480p.  I do not know if this is just a "gentleman's agreement" or if it is official.

Dan


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Subject: [opendtv] HDMI attracts three challengers
Date: Mon, 8 Jun 2009 11:24:08 -0400
From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>

Very timely article. So, should someone be lobbying NOT to have HDMI 1.4
incorporated in TVs and other boxes, because I prefer to use HDMI 1.2,
1.3, DVI, or component analog ionterfaces? All of which have lower or no
royalty fees at all?

Maybe I should become indignant about HDMI 1.4.

The reality is that we'll be seeing more and more alternatives built
into every box, we'll be paying the separate royalties, and we can
either whine about it or have fun with the added possibilities.

Bert

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HDMI attracts three challengers
Players aim to enable new class of home nets

Rick Merritt
(06/05/2009 8:00 PM EDT)
URL: http://www.eetimes.com/showArticle.jhtml?articleID=217702149

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