Do hdmi cables really make a difference on an HDTV?

Question

Do hdmi cables really make a difference on an HDTV?

Answer 1

yes they do, everything else takes the digital signal converts it to analog, transfers over the cable, and then reconverts it back to digital.  

hdmi just goes digital to digital.  theres no loss of compression at all

and if youre looking for inexpensively priced hdmi cables (they all do the same thing no matter how much you pay) check out firefold.com (used by nasa)

Answer 2

You don't say what you would be comparing to, so the answer is ... maybe. Here's my take.

The main reason for HDMI are not better picture. At most the difference will be minor vs Component, although there are much bigger differences vs S-video or Composite.

If you are using a 1080p HDTV with a Blu-ray or upconverting DVD player as a source HDMI is the preferred connection -- end of story. It's the only way to get 1080p.  The only other viable choice is Component (See the first Link) ... but it is normally limited by hardware to 1080i. Also HDMI facilitates the highest quality audio formats (digital coax or optical are limited, and discrete multichannel audio is not allways an option since many Blu-ray  players don't support it).

On a 720p HDTV (and that includes those sold as 1080i) Component is still a good option. In most cases the theoretical performance advantage of HDMI (as a digital rather than analog connection) are exactly that, theoretical.

A future consideration is HDCP (See 2nd link). When fully implemented HD video will ONLY be available via HDMI because analog connections will be downsampled to sub-HD resolution.  And HDMI will cut off video entirely if both ends of the connection are not HDCP compliant. For this reason all components intended for HD video should always be verified to be HDCP compliant. Don't buy anything that isn't.

Another consideration outside the scope of your question (effect on performance) is that HDMI is a single cable solution since it can carry both HD video and multichannel audio. Put simply it simplifies connections and can can be less expensive that the multiple cables required otherwise.

Finally, you don't (normally) require expensive HDMI cables (See 3rd link). They basically work or they don't, so $10-$15 is all you need to spend (unless you want to make long (>15') runs or embed the cables in the wall (in which case a suitable rated cable is required). The 4th link is a good on-line source for basic HDMI cables (always buy HDMI version 1.3 or better -- they are more "future proof").

Answer 3

igh-Definition Multimedia Interface

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High-Definition Multimedia Interface



HDMI cable and HDMI official logo

Type Digital audio/video connector

Production history

Designer The HDMI group

Designed December 2002

Manufacturer Various

Produced 2003

Specifications

Hot pluggable Yes

External Yes

Audio signal PCM, DVD-Audio, Super Audio CD, Dolby TrueHD, DTS-HD Master Audio

Video signal 480i, 480p, 576i, 576p, 720p, 1080i, 1080p, 1440p, etc.

Bandwidth 10.2 Gbit/s at 340 Mpixel/s

Pins 19

Pin out

Type A (Female) HDMI

Pin 1 TMDS Data2+

Pin 2 TMDS Data2 Shield

Pin 3 TMDS Data2–

Pin 4 TMDS Data1+

Pin 5 TMDS Data1 Shield

Pin 6 TMDS Data1–

Pin 7 TMDS Data0+

Pin 8 TMDS Data0 Shield

Pin 9 TMDS Data0–

Pin 10 TMDS Clock+

Pin 11 TMDS Clock Shield

Pin 12 TMDS Clock–

Pin 13 CEC

Pin 14 Reserved (N.C. on device)

Pin 15 SCL

Pin 16 SDA

Pin 17 DDC/CEC Ground

Pin 18 +5 V Power (max 50 mA)

Pin 19 Hot Plug Detect

The High-Definition Multimedia Interface (HDMI) is a compact audio/video connector interface for transmitting uncompressed digital streams. It represents a digital alternative to consumer analog standards such as RF (coaxial cable), composite video, S-Video, SCART, component video and VGA.

HDMI connects digital audio/video sources such as a set-top box, a Blu-ray Disc player, a personal computer, a video game console, or an AV receiver to a compatible digital audio device and/or video monitor such as a digital television (DTV). HDMI can use HDCP to encrypt the signal if required by the source device. HDMI began to appear in 2006 on consumer HDTV camcorders and high-end digital still cameras.[1][2] Shipments of HDMI are expected to exceed that of Digital Visual Interface (DVI) in 2008, driven primarily by the Consumer Electronics (CE) Market.[3]

Contents

[hide]

    * 1 General notes

    * 2 Specifications

          o 2.1 Connectors

          o 2.2 Cable

          o 2.3 TMDS channel

          o 2.4 Consumer Electronics Control channel

          o 2.5 Content restriction

    * 3 Versions

          o 3.1 HDMI 1.0

          o 3.2 HDMI 1.1

          o 3.3 HDMI 1.2

          o 3.4 HDMI 1.2a

          o 3.5 HDMI 1.3

          o 3.6 HDMI 1.3a

          o 3.7 HDMI 1.3b

    * 4 Cable length

    * 5 HDMI and high-definition optical media players

    * 6 Competition with DisplayPort

    * 7 See also

    * 8 References and notes

    * 9 External links

[edit] General notes

HDMI supports, on a single cable, any TV or PC video format, including standard, enhanced or high-definition video, plus multi-channel digital audio. It is independent of the various DTV standards such as ATSC, and DVB (-T,-S,-C), as these are encapsulations of the MPEG movie data streams, which are passed off to a decoder and output as uncompressed video data on HDMI. HDMI encodes the video data into TMDS for transmission digitally over HDMI.

Devices are manufactured to adhere to various versions of the specification, where each version is given a number, such as 1.0 or 1.3. Each subsequent version of the specification uses the same cables, but increases the throughput and/or capabilities of what can be transmitted over the cable. For example, previously, the maximum pixel clock rate of the interface was 165 MHz, sufficient for supporting 1080p at 60 Hz or WUXGA (1920x1200), but HDMI 1.3 increased that to 340 MHz, providing support for WQXGA (2560x1600) and beyond across a single digital link. See also: HDMI Versions.

HDMI also includes support for 8-channel uncompressed digital audio at 192 kHz sample rate with 24 bits/sample as well as any compressed stream such as Dolby Digital, or DTS. HDMI supports up to 8 channels of one-bit audio, such as that used on Super Audio CDs at rates up to 4x that used by Super Audio CD. With version 1.3, HDMI now also supports lossless compressed streams such as Dolby TrueHD and DTS-HD Master Audio.

HDMI is backward-compatible with the single-link Digital Visual Interface carrying digital video (DVI-D or DVI-I, but not DVI-A) used on modern computer monitors and graphics cards. This means that a DVI-D source can drive an HDMI monitor, or vice versa, by means of a suitable adapter or cable, but the audio and remote control features of HDMI will not be available. Additionally, without support for High-bandwidth Digital Content Protection (HDCP) on the display, the signal source may prevent the end user from viewing or recording certain restricted content.

PCs with hardware HDMI output may require software support from Operating Systems such as Windows Vista. Linux currently supports video output through backward-compatibility with DVI.

In the US, HDCP-support is a standard feature on digital TVs with built-in digital (ATSC) tuners. Among the PC-display industry, where computer displays rarely contain built-in tuners, HDCP support is absent from many models. For example, the first LCD monitors with HDMI connectors did not support HDCP, and few compact-LCD monitors (17" or smaller) support HDCP.

The HDMI Founders include consumer electronics manufacturers Hitachi, Matsushita Electric Industrial (Panasonic/National/Quasar), Philips, Sony, Thomson (RCA), Toshiba, and Silicon Image. Digital Content Protection, LLC (a subsidiary of Intel) is providing HDCP for HDMI. In addition, HDMI has the support of major motion picture producers Fox, Universal, Warner Bros., and Disney, and system operators DirecTV and EchoStar (Dish Network) as well as CableLabs and Samsung.

[edit] Specifications

HDMI defines the protocol and electrical specifications for the signaling, as well as the pin-out, electrical and mechanical requirements of the cable and connectors.

[edit] Connectors

The HDMI Specification has expanded to include three connectors, each intended for different markets.

The standard Type A HDMI connector has 19 pins, with bandwidth to support all SDTV, EDTV and HDTV modes and more. The plug outside dimensions are 13.9 mm wide by 4.45 mm high. Type A is electrically compatible with single-link DVI-D.

A higher resolution version called Type B is defined in HDMI 1.0. Type B has 29 pins (21.2 mm wide), allowing it to carry an expanded video channel for use with very high-resolution future displays, such as WQSXGA (3200x2048). Type B is electrically compatible with dual-link DVI-D, but is not in general use.

The Type C mini-connector is intended for portable devices. It is smaller than Type A (10.42 mm by 2.42 mm) but has the same 19-pin configuration.

[edit] Cable

The HDMI cable can be used to carry video, audio, and/or device-controlling signals (CEC). Adaptor cables, from Type A to Type C, are also available.

There are revisions in HDMI cabling specifications relevant to data throughput, of which all HDMI cables are backwards compatible, with HDMI 1.3 being the latest and Category 2 being the highest (greater than HDTV or Category 1). Typically HDMI cables are significantly more expensive than other cabling standards, not because of the cable’s manufacturing cost, but at a price most consumers are willing to pay, being still relatively high-end boutique. Many on-line retailers and auction sites are now offering high-end HDMI cables at prices similar to coaxial and RCA cabling, fractions of what most retailers are currently charging.

[edit] TMDS channel

The Transition Minimized Differential Signaling (TMDS) channel:

    * Carries video, audio, and auxiliary data via one of three modes called the Video Data Period, the Data Island Period, and the Control Period. During the Video Data Period, the pixels of an active video line are transmitted. During the Data Island period (which occurs during the horizontal and vertical blanking intervals), audio and auxiliary data are transmitted within a series of packets. The Control Period occurs between Video and Data Island periods.

    * Signaling method: Formerly according to DVI 1.0 spec. Single-link (Type A HDMI) or dual-link (Type B HDMI).

    * Video pixel rate: 25 MHz to 340 MHz (Type A, as of 1.3) or to 680 MHz (Type B). Video formats with rates below 25 MHz (e.g. 13.5 MHz for 480i/NTSC) are transmitted using a pixel-repetition scheme. From 24 to 48 bits per pixel can be transferred, regardless of rate. Supports 1080p at rates up to 120 Hz and WQSXGA.[4]

    * Pixel encodings: RGB 4:4:4, YCbCr 4:4:4 (8–16 bits per component); YCbCr 4:2:2 (12 bits per component)

    * Audio sample rates: 32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz, 176.4 kHz, 192 kHz.

    * Audio channels: up to 8.

    * Audio streams: any IEC61937-compliant stream, including high bitrate (lossless) streams (Dolby TrueHD, DTS-HD Master Audio).

[edit] Consumer Electronics Control channel

The Consumer Electronics Control (CEC) channel is optional to implement, but wiring is mandatory. The channel:

    * Uses the industry standard AV Link protocol.

    * Is used for remote control functions.

    * Is a one-wire bidirectional serial bus.

    * Is defined in HDMI Specification 1.0, updated in HDMI 1.2a, and again in 1.3a (added timer and audio commands).

This feature is used in two ways:

    * To allow the user to command and control multiple CEC-enabled boxes with one remote control, and

    * To allow individual CEC-enabled boxes to command and control each other, without user intervention.

An example of the latter is to allow the DVD player, when the drawer closes with a disk, to command the TV and the intervening A/V Receiver (all with CEC) to power-up, select the appropriate HDMI ports, and auto-negotiate the proper video mode and audio mode. No remote control command is needed. Similarly, this type of equipment can be programmed to return to sleep mode when the movie ends, perhaps by checking the real-tim