Talk about HDMI

[David Farber <dave () farber net>]

------ Forwarded Message
From: Dewayne Hendricks <dewayne () warpspeed com>
Reply-To: <dewayne () warpspeed com>
Date: Mon, 17 Jan 2005 15:31:17 -0800
To: Dewayne-Net Technology List <dewayne-net () warpspeed com>
Subject: [Dewayne-Net] Talk about HDMI

[Note:  I recently purchased a Sony 34" HDTV and it has an HDMI
interface.   I upgraded my DirecTV to HD and got a new box from them
(Samsung) that has DVI output, not HDMI.  I picked up a DVI to HDMI
conversion cable and it all works well.  I recently connected my
PowerBook, which has DVI output to the Sony via that same conversion
cable and it worked OK too.  The PB recognized the Sony monitor and I
was able to play movies on my PB and have them displayed in full screen
on the Sony.  Now all I need to do is pick up one of the new EyeTV 500
HD recorders for the Mac and I'll be all set for recording HD and
playing it back to the Sony from my PB.  I'm already able to play back
HD content from the Darknet in this way.  Life is good!  <g>  DLH]

Talk about HDMI
<http://anandtech.com/multimedia/showdoc.aspx?i=2321>

So, more specifically, what is HDMI? HDMI ­ High Definition Multimedia
Interface ­ is actually just a logical progression on top of DVI. The
video segment of the HDMI signal is actually compatible pin for pin
with DVI, but in a much different package. HDMI improves on DVI by
transmitting digital audio on the same interface, adding support for
HDCP and also better DDC options for manufacturers.

  HDMI provides 5Gbps over copper interconnects up to 15 feet ­ that¹s
enough headroom for a 1080p signal and 8 channel audio. For those who
like to do the math, a 1080p raw video signal and eight 192kHz audio
channels require less than 4GBps. So, there is a significant portion of
unused overhead built into the HDMI specification. We¹ve seen
demonstrations of hooking your DVD player, receiver, and PVR each with
a single cable at shows like CES and the word is that adoption of HDMI
is going even faster than originally planned.

Below, you can see a cross-section of what the 19-pin HDMI cable looks
like. The smaller, sturdier cable was designed with laptops and slimmer
devices in mind. The DVI cable on the right shows the large difference
in size.

Right now, HDMI cables, like the original DVI cables, are very
expensive. High quality cables easily retail for more than $100 each,
although middle of the pack HDMI cables in the one and two meter range
can be had for less than $20.

  Remember the interoperability and quality issues with older DVI
connectors on video cards? Since DVI is a relatively loose protocol,
manufacturers are not strictly enforced to adhere to design principles.
Signal quality on DVI connectors hit a low point in 2001/2002, but
fortunately, it seems that awareness of the problem has started to
rectify these issues. Since Silicon Image had a significant influence
on the original DVI and HDMI specifications, they have taken it upon
themselves to set up their own quality control laboratories, PanelLink
Cinema (PLC). New devices will go through a very stringent verification
process to assure that the next generation interfaces don¹t have the
same problems which plagued DVI. The lab also works directly with
Intel¹s HDCP spinoff licensor, Digital Content Protection, to assure
that HDMI-ready devices adhere to the HDCP guidelines. Copy protection
is a large facet in the HDMI specification, so it only makes sense that
Intel and Silicon Image have so much invested in building trust with
the content providers.

  Today, the largest factor that plagues HDMI in the living room is
whether or not devices are actually taking advantage of 8 channel
audio. Many of the first generation HDMI ready devices only utilized
two channels with the thought that TVs in particular would not need
anymore than 2 channels. As a result, many new devices still ship with
separate stereo inputs just as they do with DVI, but obviously, the
push will be for new devices to drop these inputs in favor of
digitally-protected high fidelity capabilities built in the cable
specification. Stereo would just be a fall back.

Archives at: <http://Wireless.Com/Dewayne-Net>
Weblog at: <http://weblog.warpspeed.com>


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