HDMI
- A constantly evolving technology
HDMI
was first introduced to the world in December 2002. This original
specification was exhaustive, being an exceptionally detailed document
outlining every detail of the HDMI bitstream, the bandwidth capabilities,
the construction of connectors and cables, as well as the encoding
and security processes. It was the manufacturer's instruction book
on how to make HDMI supporting products.
Like
any new technology, a few bugs and inconsistencies are inevitable,
and HDMI was no exception. HDMI Licensing, LLC introduced a compliance
test process to certify products of which comply to the requirements
of the specification. This was to ensure that the quality and performance
criteria as detailed in the specification were being at least adhered
to.
As
the technology evolved, new updated versions of the specification
were released. Each concurrent version is identified by a revision
number. It is important to note that each revision mainly represents
upgrades to things like bitstream content & throughput, as well
as security and encoding of data. They have not necessarily required
changes to hardware or cables, but tolerances and Q.A. may have been
tightened. For example, the original specification 1.0 is no longer
recognized in any capacity, so avoid ALL products which quote compliance
to spec 1.0.
Versions
The
various versions which have evolved through the like of HDMI to date
are ;
This
flow chart shows the different specifications, starting with the original
1.0, then progressing through to the current 1.2a
(shown in green). Spec 1.3a is a higher bandwidth
version (see the page dedicated to HDMI 1.3 here),
and is offered in conjunction with 1.2a, which also
remains current. The original spec 1.0 is depicted in gray above as
it is a now discontinued specification, and is not recognized
even by HDMI Licensing themselves. The minimum specification requirement
for the HDMI Adopter program is 1.1.
Here's
a timeline of the different versions;
HDMI
1.0 Released
December 2002.
Specification: Single-link type A connector or dual link
type B connector (latter not currently being used). Maximum bitstream
bandwidth of 4.9Gbps. Supports up to 165Mpixels/sec uncompressed
video and 8-channels of 192kHz/24-bit audio.
HDMI
1.1 Released
May 2004
Upgrades: Added support for DVD Audio. This became the
minimum specification for the new HDMI Adopter licensing program,
upon which HDMI started to take off globally
HDMI
1.2 Released
August 2005
Upgrades: Added support for 1 bit audio (SACD), and increased
support for PC application. eg: added RGB colourspace support for
PC monitors, and approval for the use of the type A connector for
PC use. Also, all 1.2 compliant displays require compatibility with
low voltage sources, namely PC video cards (the enduring problem
with the outgoing DVI format)
HDMI
1.2a Released
December 2005
Upgrades: Specifies CEC (Consumer Electronics Control)
features and command sets. Compiance test introduced for CEC functionality.
This new specification does affect many cables on the market, as
some v1.1-1.2 compliant cables did not connect the CEC channel
at all, and will not work with AV hardware of which utilizes the
CEC features (eg Panasonic).
HDMI
1.3 Released
June 2006
New Higher Specification: Increase bandwidth to 340MHz,
or 10.2 Gbps. VIDEO: Added support for 30,
36 and 48 bit deep colour (billions of colours), up from 24 bit.
Higher resolution support of up to 1440p for future PC graphics
applications AUDIO: Added new lip sync correction
feature in displays. Supports new Dolby Digital TrueHD and DTS Master
Audio surround sound formats CONNECTOR:
New "Type C" mini connector introduced for use with portable
AV devices
HDMI
1.3a Released
November 2006
Upgrades:
Cable and Sink modifications for Type C connector. Technical
upgrades for bitstream and cable construction; removed maximum rise/fall
time limits, CEC capacitance limits changed, CEC commands for timer
control modified, CEC audio control commands added, RGB video quantization
range clarified
A
matching compliance test specificationfor 1.3 has been included,
incorporating HDCP requirements (no compliance test previously available
for 1.3)
HDMI
1.3b1 Released
August 2007
Upgrades: Inclusion of type C connector in the Compliance Test Specification ("CTS")
| |
HDMI
1.1 |
HDMI
1.2a |
HDMI
1.3
Standard |
HDMI
1.3
High Speed |
| Maximum
bandwidth |
165Mpixel/sec
4.95Gbps |
165Mpixel/sec
4.95Gbps |
165Mpixel/sec
4.95Gbps |
320Mpixel/sec
10.2Gbps |
Maximum
potential resolution
dependant on devices/cables used |
1080p @ 24bit color |
1080p @ 24bit color |
1080p @ 24bit color |
Full HD 1080p
@ 48bit color |
| Minimum required resolution support |
720p/1080i
@ 24bit color |
720p/1080i
@ 24bit color |
720p/1080i
@ 24bit color |
Full HD 1080p
@ 48bit color |
| 1440p
graphics resolution support (not for movies etc) |
|
|
|
|
24
bit colour depth support
(16.7 Million colours) |
|
|
|
|
30
bit "Deep Colour" support
(1 Billion colours) |
|
|
|
|
36
bit "Deep Colour" support
(69 Billion colours) |
|
|
|
|
48
bit "Deep Colour" support
(2,800 Trillion colours) |
|
|
|
|
| 8
channel discrete 24 bit/96kHz audio |
|
|
|
|
| DVD-Audio
and SACD |
DVD-A only |
|
|
|
| Dolby®
Digital support |
|
|
|
|
| DTS
support |
|
|
|
|
| Dolby®
Digital TrueHD™ support |
|
|
|
|
| DTS
Master Audio™ support |
|
|
|
|
| Lip
Sync correction circuit in display |
|
|
|
|
| CEC
data BUS for remote control support |
|
|
|
|
| Single
Link construction |
|
|
|
|
| Requires
Licensing Approval for fully assured performance |
|
|
|
|
| Standard
19 pin "Type A" connector used |
|
|
|
|
| Optional
"Type C" mini connector for HDMI on portable AV devices |
|
|
|
|
| Compatible
with 1.1 - 1.2a devices & displays |
|
|
|
|
| Compatible
with 1.3 devices & displays for full 1.3 performance |
|
|
|
|
The
big question - do I need HDMI 1.3?
The
answer? YES. ....But, HDMI 1.3 will be the only type of HDMI cable before long. The real question is "Do I need a 'Standard' or 'High Speed' HDMI cable?". HDMI 1.3 has the same physical structure
as the previous versions, but the firmware has changed to accommodate
the new features. For example, both source
and display devices must be 1.3 compliant before you can even entertain
the idea of getting 1.3 features and performance - a 1.3 source connected
to a 1.2a sink/display will NOT get you 1.3 performance. This is because
the real differences in HDMI 1.3 are more to do with firmware than
hardware. That is, HDMI 1.3 supporting devices utilize the upgraded
firmware to enable the extra bitstream and processing features of
1.3, including the new audio formats, lip sync correction and display
input equalization. As for cables, use "High Speed" for where true 1080p will be used (ie with a native 1920x 1080 display), and "Standard" HDMI for all lesser resolutions. However if you only need to run 720p/1080i resolution, but need HD audio support, then you will probably still need a High Speed cable. For example, use a High Speed cable from your HD-DVD/Blu-ray player to your AV receiver, but you may only need a standard cable to get the video part of the signal from the output of your AV receiver to your 720p/1080i display. You can mix and match to suit the requirements of your system.
Getting a little more involved, everything in between the source and sink - cables, switchers,
AV receivers, splitters, extenders etc - all need to be wide enough bandwidth to accommodate the
requirements of your application. They do not specifically have to
state 1.3 High Speed (Cat 2) compliance, but they must be at least Standard (Cat 1) capable. A lesser
bandwidth than the upper limit of 10.2Gbps will just result in lower
end capability for 1.3, but it does not exclude 1.3 working altogether.
For example, if you use a full spec 1.2a compliant cable with a proven
bandwidth of 4.95Gbps, regardless of length, then you can still run
the extra features of HDMI 1.3, but only to a maximum resolution of
1080p at 24 bit colour. This, by the way, would be a magnificent result,
essentially being the full capability of Blu-ray or HD-DVD. It may
not matter to you that you can't get greater than 1080p, or deeper
colour than 24 bit, as you probably won't use these formats anyway.
Tech
Stuff...
Following
is a list of the bandwidth characteristics of the various resolution
and colour depth combinations, just to give you some idea of what
to look out for. These are consistent across both 1.1-1.2a and 1.3
spec systems, and include which cable types may be used with each
format;
~
720p/1080i @ 24 bit colour - 74.25MHz (2.22Gbps)
All 1.1-1.3 complaint/certified cables, length limits
may be brand dependant
~
1080p @ 24 bit colour - 148.5MHz (4.45Gbps)
Limited "Standard" cables (check with vendor), plus all HDMI 1.3 "High Speed" cables
~
720p/1080i @ 36 bit colour - 111.375MHz (3.34Gbps) Limited "Standard" cables, plus all HDMI 1.3 "High Speed" cables
~
1080p @ 36 bit colour - 222.75MHz (6.68Gbps) 1.3a (or later) "High Speed" Category 2 test only - requires 1.3 equalizing sink device
~
720p/1080i @ 48 bit colour - 148.5MHz (4.45Gbps) Limited "Standard" cables, plus all HDMI 1.3 "High Speed" cables
~
1080p @ 48 bit colour - 297.0MHz (8.91Gbps)
1.3a (or later) "High Speed" Category 2 test only - requires 1.3 equalizing sink device
As
you can see, if the most you require is 1080i, you can achieve this
with a good quality "Standard" (1.3 Category 1 - 74.25MHz) cable.
However the minimum required to get 1.3a Category 2 certification, known as "High Speed", is a much larger 165MHz/4.95Gbps unequalized, or 340MHz/10.2Gbps with equalized sink (display). Please check
this point thoroughly with your vendor prior to purchase.
HDMI
Compliance Testing
Sorry to push this point, but it is important...! There
are two main test categories which were announced with the release
of 1.3 - Category 1 for application of HDTV or less
(essentially original HDMI spec 1.1 - 1.2a @ 1080p), and Category
2 for the new higher bitrate version (beyond normal HDTV,
namely HDMI 1.3+). Essentially the tests require that the specified
bandwidth be able to be passed without interruption, and generally
the cables are the most affected by such tests. The two tests are
as follows;
-
"Standard" Category
1 - tested at 74.25MHz, which is the required bandwidth
for 720p or 1080i @ 24 bit colour depth
- "High Speed" Category
2 - tested at 165MHz non-equalized (eg for 1080p @ 24
bit colour depth), and 340MHZ equalized for extended resolutions
such as 1080p @ 48 bit colour, or 1440p
Some
existing 1.2a spec HDMI cables may already have the ability to pass
the required bandwidth of HDMI 1.3, in which case they can be used
successfully with HDMI 1.3 sources and displays without the need to
buy specifically labelled 1.3 cables. Any cable which quotes specification
1.1 may however not meet the requirements of 1.3 due to the possible
exclusion of the CEC channel, amongst other things. Please check with the cable brand/manufacturer
(and not necessarily the retailer) as to the specification compliance
of their products. Compliance criteria should be noted on their website
- if no specification is listed, DO NOT assume compliance to any degree.
A
manufacturer is free to evolve their own R&D for HDMI supporting
products, as long as the results comply with at least the minimum
requirements of the HDMI specifications and tests. By default, many
elements of construction and firmware will be totally consistent in
order to ensure compliance, but the products may evolve the technology
even futher. A good example is the advancements made by some cable
manufacturers whom have achieved cable lengths in excess of 20m, even
though the HDMI specification only suggests 5m.
In
closing, it's a good idea to always check your intended combination
of HDMI products and cables in-store before taking them home. If a
combination does not work, do not automatically blame the cables,
as it may be a little more complex than that!
