New dvi. Comparison of DVI connector with HDMI and Display Port

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Besides the fact that LCD monitors require digital data to display images, they differ from classic CRT displays in several other ways. For example, depending on the capabilities of the monitor, almost any resolution can be displayed on a CRT, since the tube does not have a clearly defined number of pixels.

And LCD monitors, due to the principle of their operation, always have a fixed (“native”) resolution at which the monitor will provide optimal quality Pictures. This limitation has nothing to do with DVI, since its main reason lies in the architecture of the LCD monitor.

An LCD monitor uses an array of tiny pixels, each made up of three diodes, one for each primary color (RGB: red, green, blue). The LCD screen, which has a native resolution of 1600x1200 (UXGA), consists of 1.92 million pixels!

Of course, LCD monitors are capable of displaying other resolutions. But in such cases, the image will have to be scaled or interpolated. If, for example, an LCD monitor has a native resolution of 1280x1024, then the lower resolution of 800x600 will be stretched to 1280x1024. The quality of interpolation depends on the monitor model. An alternative is to display the reduced image in the “native” resolution of 800x600, but in this case you will have to be content with a black frame.

Both frames show the image from the LCD monitor screen. On the left is an image in “native resolution” 1280x1024 (Eizo L885). On the right is an interpolated image at 800x600 resolution. As a result of increasing the pixels, the picture appears blocky. Such problems do not exist on CRT monitors.

To display a 1600x1200 (UXGA) resolution with 1.92 million pixels and a 60Hz vertical refresh rate, the monitor requires high bandwidth. If you do the math, you need a frequency of 115 MHz. But the frequency is also affected by other factors, such as the passage of the blanking region, so the required bandwidth increases even more.

About 25% of all transmitted information relates to blanking time. It is needed to change the position of the electron gun to the next line in the CRT monitor. At the same time, LCD monitors require virtually no blanking time.

For each frame, not only image information is transmitted, but also the boundaries and the blanking area are taken into account. CRT monitors require a blanking time to turn off the electron gun when it finishes printing a line on the screen and move it to the next line to continue printing. The same thing happens at the end of the picture, that is, in the lower right corner - the electron beam turns off and changes position to the upper left corner of the screen.

About 25% of all pixel data relates to blanking time. Since LCD monitors do not use an electron gun, the blanking time is completely useless here. But it had to be taken into account in the DVI 1.0 standard, since it allows you to connect not only digital LCDs, but also digital CRT monitors (where the DAC is built into the monitor).

The extinction time turns out to be very important factor when connecting an LCD display via a DVI interface, since each resolution requires a certain bandwidth from the transmitter (video card). The higher the required resolution, the higher the pixel frequency of the TMDS transmitter must be. The DVI standard specifies a maximum pixel frequency of 165 MHz (one channel). Thanks to the 10x frequency multiplication described above, we get a peak data throughput of 1.65 GB/s, which will be enough for a resolution of 1600x1200 at 60 Hz. If higher resolution is required, the display should be connected via Dual Link DVI, then the two DVI transmitters will work together, which will double the throughput. This option is described in more detail in the next section.

However, a simpler and cheaper solution would be to reduce the blanking data. As a result, graphics cards will be given more bandwidth, and even a 165 MHz DVI transmitter will be able to handle higher resolutions. Another option is to reduce the horizontal refresh rate of the screen.

The top of the table shows the resolutions supported by a single 165 MHz DVI transmitter. Reducing the blanking data (middle) or refresh rate (Hz) allows higher resolutions to be achieved.

This illustration shows what pixel clock is required for a specific resolution. Top line shows LCD monitor operation with reduced blanking data. The second row (60Hz CRT GTF Blanking) shows the required LCD monitor bandwidth if the blanking data cannot be reduced.

The limitation of the TMDS transmitter to a pixel frequency of 165 MHz also affects the maximum possible resolution of the LCD display. Even if we reduce the damping data, we still run into certain limit. Yes, and reducing the horizontal refresh rate may not give much good result in some applications.

To solve this problem, the DVI specification provides an additional operating mode called Dual Link. IN in this case a combination of two TMDS transmitters is used, which transmit data to one monitor through one connector. The available bandwidth doubles to 330 MHz, which is enough to output almost any existing resolution. Important Note: A video card with two DVI outputs is not a Dual Link card, which has two TMDS transmitters running through one DVI port!

The illustration shows dual-link DVI operation when two TMDS transmitters are used.

However, a video card with good DVI support and reduced blanking information will be quite enough to display information on one of the new 20" and 23" Apple Cinema displays in the "native" resolution of 1680x1050 or 1920x1200, respectively. At the same time, to support a 30" display with a resolution of 2560x1600, there is no escape from the Dual Link interface.

Due to the high “native” resolution of 30" apple display Cinema requires Dual Link DVI connection!

Although dual DVI connectors have already become standard on high-end 3D workstation cards, not all consumer-grade graphics cards can boast this. Thanks to two DVI connectors, we can still use an interesting alternative.

In this example, two single-link ports are used to connect a nine-megapixel (3840x2400) display. The picture is simply divided into two parts. But both the monitor and the video card must support this mode.

Currently, you can find six different DVI connectors. Among them: DVI-D for a completely digital connection in single-link and dual-link versions; DVI-I for analog and digital connections in two versions; DVI-A for analog connection and a new VESA DMS-59 connector. Most often manufacturers graphic cards equip their products with dual-channel DVI-I connector, even if the card has one port. Using an adapter, the DVI-I port can be converted into an analog VGA output.

Overview of various DVI connectors.

DVI connector layout.

The DVI 1.0 specification does not specify the new dual-link DMS-59 connector. It was introduced by the VESA Working Group in 2003 and allows dual DVI outputs to be output on small form factor cards. It is also intended to simplify the layout of connectors on cards that support four displays.

Finally, we come to the core of our article: the quality of TMDS transmitters of different graphics cards. Although the DVI 1.0 specification stipulates a maximum pixel frequency of 165 MHz, not all video cards produce an acceptable signal at it. Many allow you to achieve 1600x1200 only at reduced pixel frequencies and with reduced blanking times. If you try to connect a 1920x1080 HDTV device to such a card (even with reduced blanking time), you'll be in for an unpleasant surprise.

All GPUs shipped today from ATi and nVidia already have an on-chip TMDS transmitter for DVI. Manufacturers of ATi GPU cards most often use an integrated transmitter for the standard 1xVGA and 1xDVI combination. By comparison, many nVidia GPU cards use an external TMDS module (for example, from Silicon Image), even though there is a TMDS transmitter on the chip itself. To provide two DVI outputs, the card manufacturer always installs a second TMDS chip, regardless of which GPU the card is based on.

The following illustrations show common designs.

Typical configuration: one VGA and one DVI output. The TMDS transmitter can be either integrated into the graphics chip or placed on a separate chip.

Possible DVI configurations: 1x VGA and 1x Single Link DVI (A), 2x Single Link DVI (B), 1x Single Link and 1x Dual Link DVI, 2x Dual Link DVI (D). Note: if the card has two DVI outputs, this does not mean that they are dual-link! Figures E and F show the configuration of the new DMS-59 VESA ports with high density, where four or two single-link DVI outputs are provided.

As further testing in our article will show, the quality of DVI output on ATi or nVidia cards varies greatly. Even if the individual TMDS chip on a card is known for its quality, this does not mean that every card with that chip will provide a high-quality DVI signal. Even its location on the graphics card greatly affects the final result.

DVI compatible

To test the DVI quality of modern graphics cards on ATi and nVidia processors, we sent six sample cards to the Silicon Image test labs to check compatibility with the DVI standard.

Interestingly, to obtain a DVI license it is not at all necessary to conduct compatibility tests with the standard. As a result, products are entering the market that claim to support DVI but do not meet the specifications. One of the reasons for this state of affairs is the complex and therefore expensive testing procedure.

In response to this problem, Silicon Image founded a test center in December 2003. DVI Compliance Test Center (CTC). Manufacturers of DVI-enabled devices may submit their products for DVI compatibility testing. In fact, that's what we did with our six graphics cards.

The tests are divided into three categories: transmitter (usually a video card), cable, and receiver (monitor). To evaluate DVI compatibility, so-called eye diagrams are created to represent the DVI signal. If the signal does not go beyond certain limits, then the test is considered passed. Otherwise, the device is not compatible with the DVI standard.

The illustration shows the eye diagram of a TMDS transmitter at 162 MHz (UXGA) transmitting billions of bits of data.

The eye diagram test is the most important test to evaluate signal quality. The diagram shows signal fluctuations (phase jitter), amplitude distortion and the “ringing” effect. These tests also allow you to clearly see the quality of DVI.

DVI compatibility tests include the following checks.

Transmitter: Eye diagram with specified boundaries.
Cables: Eye diagrams are created before and after signal transmission, then compared. Once again, the signal deviation limits are strictly defined. But here large discrepancies with the ideal signal are already allowed.
Receiver: The eye diagram is again created, but again, even greater discrepancies are allowed.

The biggest problems with serial high-speed transmission are signal phase jitter. If there is no such effect, then you can always clearly highlight the signal on the chart. Most signal jitter is generated by the graphics chip's clock signal, resulting in low-frequency jitter in the 100 kHz to 10 MHz range. In an eye diagram, signal fluctuation is noticeable by changes in frequency, data, data relative to frequency, amplitude, too much or too little rise. Additionally, DVI measurements vary at different frequencies, which must be taken into account when checking the eye diagram. But thanks to the eye diagram, you can clearly evaluate the quality of the DVI signal.

For measurements, one million overlapping areas are analyzed using an oscilloscope. This is sufficient to evaluate the overall performance of a DVI connection since the signal will not change significantly over a long period of time. Graphical representation of the data is produced using special software that Silicon Image created in collaboration with Tektronix. A signal that complies with the DVI specification must not interfere with the boundaries (blue areas) that are automatically drawn software. If the signal falls into the blue area, the test is considered failed and the device does not comply with the DVI specification. The program immediately shows the result.

The video card did not pass the DVI compatibility test.

The software immediately shows whether the card passed the test or not.

Different boundaries (eyes) are used for the cable, transmitter and receiver. The signal should not interfere with these areas.

To understand how DVI compatibility is determined and what needs to be considered, we need to dive into more detail.

Since DVI transmission is completely digital, the question arises where the signal phase jitter comes from. Two reasons can be put forward here. The first is that jitter is caused by the data itself, that is, the 24 parallel bits of data that the graphics chip produces. However, the data is automatically corrected in the TMDS chip when necessary, ensuring that there is no jitter in the data. Therefore, the remaining cause of jitter is the clock signal.

At first glance, the data signal appears to be free of interference. This is guaranteed thanks to the latch register built into the TMDS. But the main problem still remains the clock signal, which spoils the data flow through the 10x PLL multiplication.

Since the frequency is multiplied by a factor of 10 by the PLL, the impact of even small amounts of distortion is magnified. As a result, the data reaches the receiver no longer in its original state.

Above is an ideal clock signal, below is a signal where one of the edges began to be transmitted too early. Thanks to the PLL, this directly affects the data signal. In general, every disturbance in the clock signal results in errors in data transmission.

When the receiver samples the corrupted data signal using the "ideal" hypothetical PLL clock, it receives erroneous data (yellow bar).

How it actually works: If the receiver uses a corrupted transmitter clock signal, it will still be able to read the corrupted data (red bar). This is why the clock signal is also transmitted over the DVI cable! The receiver requires the same (damaged) clock signal.

The DVI standard includes jitter management. If both components use the same corrupted clock signal, then information can be read from the corrupted data signal without error. Thus, DVI-compatible devices can operate even in environments with low-frequency jitter. The error in the clock signal can then be bypassed.

As we explained above, DVI works optimally if the transmitter and receiver use the same clock signal and their architecture is the same. But this doesn't always happen. This is why using DVI can cause problems despite sophisticated anti-jitter measures.

The illustration shows the optimal scenario for DVI transmission. Multiplying the clock signal in the PLL introduces a delay. And the data flow will no longer be consistent. But everything is corrected by taking into account the same delay in the receiver's PLL, so the data is received correctly.

The DVI 1.0 standard clearly defines PLL latency. This architecture is called non-coherent. If the PLL does not meet these latency specifications, problems may arise. There is heated debate in the industry today about whether such a decoupled architecture should be used. Moreover, a number of companies are in favor of a complete revision of the standard.

This example uses the PLL clock signal instead of the graphics chip signal. Therefore, the data signals and clock signals are consistent. However, due to the delay in the receiver's PLL, the data is not processed correctly, and jitter removal no longer works!

You should now understand why using long cables can be problematic, even without taking into account external interference. A long cable can introduce delay into the clock signal (remember that data signals and clock signals have different frequency ranges), additional delay can affect the quality of signal reception.

To transmit video signals in digital form, a DVI (digital visual interface) connector is used. It was created when video media appeared in digital format - DVDs, and when it was necessary to transfer video from a computer to a monitor. The then existing methods of transmitting an analog signal did not allow achieving High Quality pictures, because it is physically impossible to transmit a high-resolution analog signal over a distance.

Video distortion can always occur in the communication channel, this is especially noticeable on high frequencies oh, and HD quality just implies the presence of high frequencies in the signal spectrum. To avoid these distortions, we tried to switch to digital signal and abandon analog when processing and transmitting video from the media to the display device. Then, in the late 90s, several companies joined forces to create a digital interface for transmitting video data, eliminating DAC (digital-to-analog) and ADC (analog-to-digital) converters from the path. The result of their work was the creation of the video signal transmission format - DVI.

Appearance of dvi connector:

View of the dvi connector inside:

Basic parameters of the dvi interface

This type of connection transmits information about the main components of the RGB signal (red, green, blue). Each component uses a separate twisted pair cable in the DVI cable, and a separate twisted pair cable to carry the clock signals. It turns out that the DVI cable consists of four twisted pairs. A twisted pair connection allows you to use the principle of differential data transmission, when the interference has a different phase in each conductor and is subtracted at the receiver, but these are technical features and it is not necessary to know them. Each color component is allocated 8 bits, and, in general, 24 bits of information are transmitted to each pixel. The maximum data transfer rate reaches 4.95 Gbps, at this speed you can transmit a signal with a resolution of 2.6 megapixels at a frame rate of 60 Hz. An HDTV signal, whose resolution is 1980x1080, has a resolution of slightly more than 2 megapixels, so it turns out that a high-resolution signal of 1980x1080 at 60 Hz can be transmitted through the DVI connector. There is only a limit on the cable length. It is believed that a high-resolution signal can be transmitted with a cable up to 5 meters long, otherwise distortion may occur in the image. When transmitting a signal with a lower resolution, it is permissible to increase the length of the DVI cable. It is also possible to use intermediate amplifiers if a larger length is still needed to transmit the video signal.

For greater compatibility, the DVI connector was made to support an analog signal. This is how three types of DVI connectors appeared:

1) DVI-D transmits only digital signal;
2) DVI-A transmits only analog signal;
3) DVI-I is used to transmit both digital and analog signals.

The connector itself is the same for all three types, so they are completely compatible, only they have a difference in the connected contacts in the connector.

There are also two data transfer modes: single link (single mode), dual link (double mode). Their main difference is in the supported frequencies. If in single mode the maximum signal can be 165 MHz, then in dual mode the limitation is imposed by the physical characteristics of the cable. This suggests that DVI Dual Link cables can carry signal from high resolution and over long distances. That is, if, when using a single link cable, there is interference in the image of the LCD TV in the form of colored dots, then you can try replacing it with a dual link. Structurally, a dual mode DVI cable is distinguished by the use of double twisted pairs to transmit color components.

Features of the dvi connector

To implement such speeds, a special TMDS coding method. And in any DVI connection, a TMDS transmitter is used on the transmitting side for encoding, and the RGB signal is restored on the receiving side.

Additionally can be used in DVI interface DDC channel (Display Data Channel), which provides the source processor with EDID display information. This information contains details about the display device and includes information about the brand, model number, serial number, release date, screen resolution, screen size. Depending on this information, the source will produce a signal with the required resolution and screen proportions. If the source refuses to provide such information, it may block the TMDS channel.

Just like HDMI, DVI interface supports HDCP content protection system. Such a protection system is called intelligent protection and is called so because of its implementation and the ability to set different levels of protection depending on different cases, so such protection does not block normal data exchange (for example, when copying). It is implemented on the principle of exchanging passwords with all devices connected via DVI.

Only the image is transmitted through the DVI connector, and the sound will have to be transmitted through additional channels. Some video cards have the ability to transmit audio via a DVI cable, but special adapters are used for this, and this feature is additionally implemented in the video card itself. And then it is no longer a pure DVI interface. With a normal connection, audio needs to be transmitted additionally.

Probably every user of a personal computer or laptop has encountered issues with connecting a monitor or TV to it, as well as the quality of the resulting image. And if earlier getting a high-quality picture on the screen was quite problematic, today this problem does not exist at all. Of course, if your device has a DVI connector. This is what we will talk about, and also consider other existing interfaces for displaying images on the screen.

Types of connectors for displaying images on a computer monitor or screen

Until recently, all personal computers had exclusively analog connections to the monitor. To transfer images to it, a VGA (Video Graphics Adapter) interface with a D-Sub 15 connector was used. Experienced users still remember the blue plug and 15-pin socket. But, besides this, video cards also had other connectors designed to display images on a TV screen or other video device:

RCA (Radio Corporation of America) - in our opinion, “tulip”. An analog connector designed to connect a video card to a TV, video player or VCR using coaxial cable. Has the worst transmission characteristics and low resolution.
S-Video (S-VHS) is a type of analog connector for transmitting a video signal to a TV, VCR or projector, dividing the data into three channels responsible for a separate base color. The quality of signal transmission is slightly better than “tulip”.
Component connector - output to three separate “tulips”, used to output images to the projector.

All of these connectors were widely used until the late 1990s. Of course, there was no question of quality, since both televisions and monitors at that time had very low resolution. Now we cannot even imagine how it was possible to play computer games while looking at a TV screen with a cathode ray tube.

With the advent of the new century, thanks to the introduction of digital technologies in the development of video devices, RCA, S-VHS and component output began to be used less and less. The VGA interface lasted a little longer.

A little history

The operating principle of a conventional video card was that the digital image output from it had to be converted into an analog signal using a RAMDAC device - a digital-to-analog converter. Naturally, such conversion already deteriorated the image quality at the initial stage.

With the advent digital screens there was a need to convert the analog signal at the output. Now monitors have also begun to be equipped with a special converter, which again could not but affect the image quality.

And here, in 1999, DVI appeared, seemingly out of nowhere, the latest digital video interface, thanks to which we can today enjoy the perfect picture on the screen.

The development of this interface device was carried out by a whole group of companies, which included Silicon Image, Digital Display Working Group and even Intel. The developers came to the conclusion that there is no need to convert a digital signal to analog, and then vice versa. It is enough to create a single interface, and the image in its original form will be displayed on the screen. And without the slightest loss of quality.

What is DVI

DVI stands for Digital Visual Interface. The essence of its work is that a special TMDS encoding protocol, also developed by Silicon Image, is used to transmit data. The method of transmitting a signal through a digital video interface is based on the sequential sending of information previously implemented by the protocol, with constant backward compatibility with analog VGA channel.

The DVI specification allows for a single TMDS connection to operate at up to 165 MHz and a transfer rate of 1.65 Gbps. This makes it possible to obtain an output image with a resolution of 1920x1080 with a maximum frequency of 60 Hz. But here it is possible to simultaneously use a second TMDS connection with the same frequency, which allows you to achieve a throughput of 2 Gbit/s.

Having such indicators, DVI left far behind other developments in this direction and began to be used on all digital devices without exception.

DVI for the average user

Without delving into the jungle of electronics, a digital video interface is just a special encoding device that has a corresponding connector on the video card. But how do you know that a computer or laptop has a digital output?

Everything is very simple. The connectors of video cards with a digital interface cannot be confused with others. They have a specific appearance and shape, different from other nests. In addition, the DVI connector is always white, which makes it stand out from the rest.

In order to connect a monitor, TV or projector to a video card, you simply plug in the plug of the desired wire and secure it using special hand-screwed bolts.

Resolution and scaling

However, neither digital coding nor special video card connectors have completely solved the problem of computer-monitor compatibility. A question arose about image scaling.

The fact is that all monitors, screens and televisions that already have a DVI connector are not capable of producing a higher output resolution than that provided by their design. Therefore, it often happened that the video card produced a high-quality picture, and the monitor showed it to us only in a quality limited by its capabilities.

The developers caught on in time and began equipping all modern digital panels with special scaling devices.

Now, when we connect the DVI connector on the monitor to the corresponding output on the video card, the device instantly self-adjusts, choosing the optimal operating mode. We usually don’t pay any attention to this process and don’t try to control it.

Video cards and DVI support

The first video cards of the NVIDIA GeForce2 GTS series already had built-in TMDS transmitters. They are still widely used today in Titanium cards, being integrated into rendering devices. The disadvantage of built-in transmitters is their low clock frequency, which does not allow achieving high resolution. In other words, TMDS do not make the most of their advertised 165 MHz bandwidth. Therefore, we can say with confidence that NVIDIA at the initial stage failed to adequately implement the DVI standard in its video cards.

When video adapters began to be equipped with an external TMDS, working in parallel with the built-in one, the DVI interface was able to produce a resolution of 1920x1440, which exceeded all the expectations of the company's developers.

The Titanium GeForce GTX series had no problems at all. They effortlessly provide images with a resolution of 1600x1024.

ATI took a completely different path. All of its video cards that have DVI outputs also operate from integrated transmitters, but they are supplied complete with special DVI-VGA adapters that connect 5 analog DVI pins to VGA.

Maxtor specialists decided not to bother at all and came up with their own way out of the situation. The G550 series video cards are the only ones that have a dual DVI cable instead of two signal transmitters. This solution allowed the company to achieve a resolution of 1280x1024 pixels.

DVI connector: types

It's important to know that not all digital connectors are created equal. They have different specifications and designs. In our daily life, the following types of DVI connectors are most often encountered:

DVI-I SingleLink;
DVI-I DualLink;
DVI-D SingleLink;
DVI-D DualLink;
DVI-A.

DVI-I SingleLink connector

This connector is the most popular and in demand. It is used in all modern video cards ah and digital monitors. The letter I in the name means “integrated”. This DVI connector is special in its own way. The fact is that it has two combined transmission channels: digital and analog. In other words, this is a DVI+VGA connector. It has 24 digital pins and 5 analog pins.

Considering that these channels are independent of each other and cannot be used simultaneously, the device independently chooses which one to work with.

By the way, the first such integrated interfaces had separate DVI and VGA connectors.

DVI-I DualLink connector

DVI-I DualLink is also capable of transmitting an analog signal, but, unlike SingleLink, it has two digital channels. Why is this necessary? Firstly, to improve throughput, and secondly, it all comes down to resolution again, which is directly proportional to image quality. This option allows you to expand it to 1920x1080.

DVI-D SingleLink connector

DVI-D SingleLink connectors do not have any analog channels. The letter D informs the user that this is a digital interface only. It has one transmission channel and is also limited to a resolution of 1920x1080 pixels.

DVI-D DualLink connector

This connector has two data channels. Their simultaneous use makes it possible to obtain 2560x1600 pixels at a frequency of only 60 Hz. In addition, this solution allows some modern video cards, such as nVidia 3D Vision, to reproduce three-dimensional images on a monitor screen with a resolution of 1920x1080 with a refresh rate of 120 Hz.

DVI-A connector

In some sources, the concept of DVI-A is sometimes found - a digital connector for transmitting exclusively an analog signal. In order not to mislead you, let us immediately indicate that in fact such an interface does not exist. DVI-A is just a special plug in cables and special adapters for connecting analog video devices to the DVI-I connector.

Digital connector: pinout

All of the connectors listed differ from each other in the location and number of contacts:

DVI-I SingleLink - has 18 pins for digital channel and 5 for analog;
DVI-I DualLink - 24 digital pins, 4 analog, 1 - ground;
DVI-D SingleLink - 18 digital, 1 - ground;
DVI-D DualLink - 24 digital, 1 - ground

The DVI-A connector also has its own unique pin arrangement. Its pinout consists of only 17 pins, including ground.

HDMI connector

A modern digital video interface also has other types of connecting communications. For example, the HDMI DVI connector is in no way inferior in popularity to the listed models. On the contrary, thanks to its compactness and capabilities, together with digital video transmit audio signal, it has become a mandatory accessory for all new TVs and monitors.

The abbreviation HDMI stands for High Definition Multimedia Interface, which means “high-definition multimedia interface.” It appeared for the first time in 2003 and since then has not lost any of its relevance. Every year new modifications appear with improved resolution and bandwidth.

Today, for example, HDMI makes it possible to transmit video and audio signals without loss of quality over a cable up to 10 meters long. The throughput is up to 10.2 Gb/s. Just a few years ago this figure did not exceed 5 Gb/s.

Support and development this standard The world's leading companies producing radio electronics are engaged in this: Toshiba, Panasonic, Sony, Philips, etc. Almost all video devices today manufactured by these manufacturers must have at least one HDMI connector.

DP connector

DP (DisplayPort) is the newest connector that replaced the HDMI multimedia interface. Possessing high throughput, minimal loss of quality during data transmission and compactness, it was designed to completely replace the DVI standard. But it turned out that not everything is so simple. Majority modern monitors do not have the appropriate connectors, and change the system of their production in short time- it’s an impossible task. In addition, not all manufacturers are particularly committed to this, which is why most video equipment is not equipped with the DisplayPort standard.

Mini connectors

Today, when computers are often replaced by more mobile devices: laptops, tablets and smartphones - using conventional connectors becomes not very convenient. Therefore, manufacturers such as Apple, for example, began to replace them with smaller analogues. First VGA became mini-VGA, then DVI became micro-DVI, and DisplayPort shrank to mini-DisplayPort.

DVI adapters

But what if, for example, you need to connect a laptop to an analog monitor or another device that has a DVI connector to a digital panel with HDMI or DisplayPort standard? Special adapters will help with this, which can be purchased today at any radio electronics store.

Let's look at their main types:

VGA - DVI;
DVI - VGA;
DVI - HDMI;
HDMI - DVI;
HDMI - DisplayPort;
DisplayPort - HDMI.

In addition to these basic adapters, there are also varieties of them that provide connection to other interfaces, such as USB.

Of course, with such a connection there is a loss of image quality, even between devices of the same type that support the DVI standard. An adapter connector, no matter how high-quality it is, cannot solve this problem.

How to connect a TV to a computer

Connecting a TV to a computer or laptop is not difficult, but you should determine which interface is equipped with both devices. Most modern television receivers have built-in connectors that support DVI. This can be either HDMI or DisplayPort. If a computer or laptop has the same connector as the TV, it is enough to use the cable that usually comes with the latter. If the wire was not included in the kit, you can freely buy it in the store.

The computer operating system will independently detect the connection of the second screen and offer one of the options for using it:

as the main monitor;
in clone mode (the image will be displayed on both screens);
as an additional monitor to the main one.

But do not forget that with such a connection, the image resolution will remain the same as provided for by the screen design.

Does cable length affect signal quality?

Not only the signal quality, but also the data transfer speed depends on the length of the cable connecting the device and the screen. Taking into account the modern characteristics of connecting wires for various digital interfaces, their length should not exceed the established parameters:

for VGA - no more than 3 m;
for HDMI - no more than 5 m;
for DVI - no more than 10 m;
for DisplayPort - no more than 10 m.

If you need to connect a computer or laptop to a screen located at a distance exceeding the recommended one, you must use a special amplifier - a repeater (signal repeater), which can also distribute the channel to several monitors.

The DVI connector is used in modern TVs(plasma, liquid crystal), LCD monitors and video cards of personal computers. The name "DVI" comes from the English abbreviation Digital VisualInterface, which translates as "digital video interface". The DVI connector was developed and first introduced back in 1999 by the Digital Display Working Group. It includes global giants in the production of computer equipment and monitors, such as Intel, Compaq, Fujitsu, Silicon Image, Hewlett Packard and NEC. The DVI connector replaced the VGA interface and today has almost completely replaced it.

Description of DVI technology

The method used in this interface was developed by Silicon Image. It is a type of serial communication device. The DVI cable is built on the twisted pair principle. Three pairs of wires carry colors (red, green and blue), and the fourth carries clock signals. The DVI connector allows you to transmit both analog and There are three subtypes of the interface in question:

DVI-A - used for transmission exclusively;
DVI-I is a universal connector, used for transmitting both analog and digital signals;
DVI-D - for transmitting digital signals only.

In addition, DVI technology is equipped with a special HDCP digital information protection system developed by Intel.

Disadvantages of the DVI interface

The main disadvantage of transmitting information through this connector is the limitation of the cable length, as well as the dependence of the mentioned parameter on the type of signal being transmitted. For example, an image with an extension of 1920x1200 pixels at a frequency of 60 Hz can be transmitted over a cable whose length is 5 meters, and through a fifteen-meter cable it is possible to transmit a signal whose maximum quality is only 1280x1024 pixels at the same frequency. Therefore, if it is necessary to use long cables, you have to use optional equipment- special signal amplifiers (repeaters), which are installed at certain distances. This disadvantage is associated with the appearance of dots on the monitor when using a low-quality cable. To eliminate this effect, you must either change the cord or reduce the quality of the input signal.

DVI-HDMI connector

This digital connector is used to transmit HDTV signals. Designed to connect TVs to various signal sources. The peculiarity of the mentioned connector is that through it you can transmit not only a video signal, but also digital audio. It allows you to broadcast 8 audio channels with a bit depth of 24 bits. There are various specifications for the designated interface, as well as adapters, thanks to which you can connect different types of connectors. The HDMI connector can also be used to connect a personal computer and a TV. It should be remembered that the HDMI-DVI interface supports a special protocol designed to protect licensed content from unauthorized overwriting.

Conclusion

Despite the fact that DVI technology has almost completely replaced VGA interfaces, today this type is quite widely used on older PCs. If your video card does not have a DVI connector, but you still need to connect a monitor that supports this technology, then you can use a special adapter - a DVI-VGA connector.

The choice of video card can also be influenced by the monitor you have or are planning to purchase. Or even monitors (plural). So, for modern LCD monitors with digital inputs, it is very desirable that the video card have DVI connector, HDMI or DisplayPort. Fortunately, all modern solutions now have such ports, and often all together. Another subtlety is that if you require a resolution higher than 1920x1200 via the digital DVI output, then you must connect the video card to the monitor using a connector and cable that supports Dual-Link DVI. However, now there are no problems with this anymore. Let's look at the main connectors used to connect information display devices.

Analog D-Sub connector (also known as VGA-exit or DB-15F)

This is a long-known and familiar 15-pin connector for connecting analog monitors. The abbreviation VGA stands for video graphics array (pixel array) or video graphics adapter (video adapter). The connector is designed to output an analog signal, the quality of which can be influenced by many different factors, such as the quality of RAMDAC and analog circuits, so the quality of the resulting image may vary on different video cards. In addition, in modern video cards the quality analog output less attention is paid, and to get clear pictures at high resolutions it is better to use a digital connection.

D-Sub connectors were actually the only standard until the widespread use of LCD monitors. Such outputs are still often used to connect LCD monitors, but only budget models that are not well suited for gaming. To connect modern monitors and projectors, it is recommended to use digital interfaces, one of the most common of which is DVI.

Connector DVI(variations: DVI-I And DVI-D)

DVI is the standard interface most often used to output digital video to all but the cheapest LCD monitors. The photo shows quite old video card with three connectors: D-Sub, S-Video and DVI. There are three types of DVI connectors: DVI-D (digital), DVI-A (analog) and DVI-I (integrated - combined or universal):

DVI-D- an exclusively digital connection, which avoids losses in quality due to double conversion of the digital signal to analog and from analog to digital. This type of connection provides the highest quality picture, it outputs the signal only in digital form, digital LCD monitors with DVI inputs or professional CRT monitors with built-in RAMDAC and a DVI input can be connected to it (very rare copies, especially now). This connector differs from DVI-I in the physical absence of some contacts, and the DVI-to-D-Sub adapter, which will be discussed later, cannot be plugged into it. Most often this DVI type used in motherboards with an integrated video core; it is less common on video cards.

DVI-A- This is a rather rare type of analog connection via DVI, designed to output analog images to CRT receivers. In this case, the signal is degraded due to dual digital-to-analog and analog-to-digital conversion, its quality is equal to that of a standard VGA connection. Almost never found in nature.

DVI-I is a combination of the two options described above, capable of transmitting both analog and digital signals. This type is used most often in video cards; it is universal and, using special adapters that come with most video cards, you can also connect a regular analog CRT monitor with a DB-15F input to it. This is what these adapters look like:

All modern video cards have at least one DVI output, or even two universal DVI-I connectors. D-Subs are most often absent (but they can be connected using adapters, see above), except, again, for budget models. To transmit digital data, either a single-channel DVI Single-Link solution or a two-channel Dual-Link solution is used. Single-Link transmission format uses one TMDS transmitter (165 MHz) and Dual-Link two, it doubles the bandwidth and allows screen resolutions higher than 1920x1080 and 1920x1200 at 60Hz, supporting very high resolution modes , like 2560x1600. Therefore, for the largest LCD monitors with high resolution, such as 30-inch models, as well as monitors designed to display stereo images, you will definitely need a video card with a dual-channel DVI Dual-Link or HDMI version 1.3 output.

Connector HDMI

IN Lately a new one has become widespread home interface — High Definition Multimedia Interface. This standard provides simultaneous transmission of visual and audio information over a single cable, it is designed for television and cinema, but PC users can also use it to output video data using the HDMI connector.

In the photo on the left is HDMI, on the right is DVI-I. HDMI outputs on video cards are now quite common, and there are more and more such models, especially in the case of video cards intended for creating media centers. Viewing high-definition video on a computer requires a video card and monitor that support HDCP content protection, connected by an HDMI or DVI cable. Video cards do not necessarily have to have an HDMI connector on board; in other cases, the HDMI cable can also be connected via an adapter to DVI:

HDMI is the latest effort to standardize universal connectivity for digital audio and video applications. It immediately received strong support from the giants of the electronics industry (the group of companies involved in developing the standard includes companies such as Sony, Toshiba, Hitachi, Panasonic, Thomson, Philips and Silicon Image), and most modern high-resolution output devices have although There would be one such connector. HDMI allows you to transmit copy-protected audio and video in digital format over a single cable; the first version of the standard was based on a bandwidth of 5 Gbps, and HDMI 1.3 expanded this limit to 10.2 Gbps.

HDMI 1.3 is an updated standard specification with increased interface bandwidth, increased clock frequency to 340 MHz, which allows you to connect high-resolution displays that support more colors (formats with color depths up to 48 bits). The new version of the specification also defines support for new Dolby standards for transmitting compressed audio without loss in quality. In addition, other innovations appeared; specification 1.3 described a new mini-HDMI connector, smaller in size compared to the original. Such connectors are also used on video cards.

HDMI 1.4b is the latest new version of this standard, released not so long ago. HDMI 1.4 introduced the following major innovations: support for stereo display format (also called "3D") with frame-by-frame transmission and active viewing glasses, support for Fast Ethernet connection HDMI Ethernet Channel for data transmission, audio return channel, which allows digital audio to be transmitted in the reverse direction , support for resolution formats 3840x2160 up to 30 Hz and 4096x2160 up to 24 Hz, support for new color spaces and the smallest micro-HDMI connector.

In HDMI 1.4a, stereo display support has been significantly improved, with new Side-by-Side and Top-and-Bottom modes in addition to the 1.4 specification modes. And finally, a very recent update to the HDMI 1.4b standard occurred just a few weeks ago, and the innovations of this version are still unknown to the general public, and there are no devices with its support on the market yet.

Actually, the presence of an HDMI connector on the video card is not necessary; in many cases it can be replaced by an adapter from DVI to HDMI. It is simple and therefore included with most modern video cards. Moreover, modern GPUs have a built-in audio chip necessary to support audio transmission over HDMI. On all modern AMD and NVIDIA video cards, there is no need for an external audio solution and corresponding connecting cables, and there is no need to transfer audio from an external sound card.

Transmission of video and audio signals via one HDMI connector is in demand primarily on mid- and low-end cards, which are installed in small and quiet barebones used as media centers, although HDMI is often used in gaming solutions, largely due to the spread household appliances with these connectors.

Connector

Gradually, in addition to the common video interfaces DVI and HDMI, solutions with the DisplayPort interface are appearing on the market. Single-Link DVI transmits a video signal with a resolution of up to 1920x1080 pixels, a frequency of 60 Hz and 8 bits per color component, Dual-Link allows transmission of 2560x1600 at a frequency of 60 Hz, but already 3840x2400 pixels under the same conditions for Dual-Link Link DVI not available. HDMI has almost the same limitations; version 1.3 supports signal transmission with a resolution of up to 2560x1600 pixels at a frequency of 60 Hz and 8 bits per color component (at lower resolutions - 16 bits). Although DisplayPort's maximum capabilities are slightly higher than Dual-Link DVI's, only 2560x2048 pixels at 60 Hz and 8 bits per color channel, it does have support for 10-bit color per channel at 2560x1600 resolution, as well as 12 bit for 1080p format.

The first version of the DisplayPort digital video interface was adopted by VESA (Video Electronics Standards Association) in the spring of 2006. It defines a new universal digital interface, license-free and royalty-free, designed to connect computers and monitors, as well as other multimedia equipment. The VESA DisplayPort group that promotes the standard includes large electronics manufacturers: AMD, NVIDIA, Dell, HP, Intel, Lenovo, Molex, Philips, Samsung.

DisplayPort's main competitor is the HDMI connector, which supports HDCP write protection, although it is intended more for connecting consumer digital devices such as players and HDTV panels. Another competitor could previously be called Unified Display Interface - a less expensive alternative HDMI connectors and DVI, but its main developer, Intel, refused to promote the standard in favor of DisplayPort.

The absence of licensing fees is important for manufacturers, because in order to use the HDMI interface in their products, they are required to pay license fees to HDMI Licensing, which then divides the funds between the holders of rights to the standard: Panasonic, Philips, Hitachi, Silicon Image, Sony, Thomson and Toshiba. Abandoning HDMI in favor of a similar “free” universal interface will save manufacturers of video cards and monitors a lot of money - it’s clear why they liked DisplayPort.

Technically, the DisplayPort connector supports up to four data lines, each of which can transmit 1.3, 2.2 or 4.3 gigabits/s, for a total of up to 17.28 gigabits/s. Modes with color depth from 6 to 16 bits per color channel are supported. An additional bidirectional channel, designed to transmit commands and control information, operates at a speed of 1 megabit/s or 720 megabit/s and is used to service the operation of the main channel, as well as the transmission of VESA EDID and VESA MCCS signals. Also, unlike DVI, the clock signal is transmitted along signal lines, rather than separately, and is decoded by the receiver.

DisplayPort has optional DPCP (DisplayPort Content Protection) copy protection capability developed by AMD and using 128-bit AES encoding. The transmitted video signal is not compatible with DVI and HDMI, but according to the specification their transmission is allowed. Currently, DisplayPort supports a maximum data transfer rate of 17.28 gigabits/s and a resolution of 3840x2160 at 60 Hz.

Basic distinctive features DisplayPort: an open and extensible standard; support RGB formats and YCbCr; color depth support: 6, 8, 10, 12 and 16 bits per color component; full signal transmission at 3 meters, and 1080p at 15 meters; support for 128-bit AES encoding DisplayPort Content Protection, as well as 40-bit High-bandwidth Digital Content Protection (HDCP 1.3); greater bandwidth compared to Dual-Link DVI and HDMI; transmission of multiple streams over one connection; compatibility with DVI, HDMI and VGA using adapters; simple expansion of the standard to meet changing market needs; external and internal connections (connecting an LCD panel in a laptop, replacing internal LVDS connections).

The updated version of the standard, 1.1, appeared a year after 1.0. Its innovations include support for HDCP copy protection, important when viewing protected content from Blu-ray discs and HD DVDs, and support for fiber optic cables in addition to conventional copper cables. The latter allows you to transmit a signal over even greater distances without loss of quality.

DisplayPort 1.2, approved in 2009, doubled the interface's throughput to 17.28 gigabits/s, allowing it to support higher resolutions, screen refresh rates, and color depths. Also, it was in 1.2 that support for transmitting multiple streams over one connection for connecting multiple monitors, support for stereo display formats and xvYCC, scRGB and Adobe RGB color spaces appeared. A smaller Mini-DisplayPort connector for portable devices has also appeared.

The full-size external DisplayPort connector has 20 pins, its physical size can be compared to all known USB connectors. A new type of connector can already be seen on many modern video cards and monitors; it looks similar to both HDMI and USB, but can also be equipped with latches on the connectors, similar to those provided in Serial ATA.

Before AMD bought ATI, the latter announced the supply of video cards with DisplayPort connectors at the beginning of 2007, but the merger of companies delayed this appearance for some time. Subsequently, AMD announced DisplayPort as a standard connector within the Fusion platform, implying a unified architecture of the central and GPUs in one chip, as well as future mobile platforms. NVIDIA is keeping up with its rivals by releasing a wide range of DisplayPort-enabled graphics cards.

Among the monitor manufacturers that announced support and announced DisplayPort products, Samsung and Dell were the first. Naturally, such support was first received by new monitors with a large screen diagonal size and high resolution. There are DisplayPort-to-HDMI and DisplayPort-to-DVI adapters, as well as DisplayPort-to-VGA, which converts a digital signal to analog. That is, even if the video card contains only DisplayPort connectors, they can be connected to any type of monitor.

In addition to the connectors listed above, older video cards also sometimes have a composite connector and S-Video (S-VHS) with four or seven pins. Most often they are used to output a signal to outdated analog television receivers, and even on S-Video the composite signal is often mixed, which negatively affects the picture quality. S-Video is better quality than composite tulip, but both are inferior to YPbPr component output. This connector is found on some monitors and high-definition TVs; the signal is transmitted through it in analog form and is comparable in quality to D-Sub interface. However, in the case of modern video cards and monitors, paying attention to all analog connectors simply does not make any sense.