Spdif color difference output S-video YUV YCbCr ypbpr rgb vga wxga detailed introduction

Spdif
Digital audio output.
Spdif is short for Sony and Philips digital audio interfaces. In terms of transmission mode, spdif can be divided into two types: output (spdif out) and input (spdif in. Currently, most sound card chips support spdif out, but we need to note that not every product provides digital interfaces. The support for spdif in sound card chip is relatively less, such as: emu10k1, YMF-744 and FM801-AU, cmi8738 and so on. The typical application of spdif in on sound cards is CD spdif, but not every sound card that supports spdif in provides this interface. As far as the transmission carrier is concerned, spdif is divided into two types: coaxial and optical fiber. In fact, they can transmit the same signal, but the carrier is different, and the interface and connection appearance are also different. However, optical signal transmission is a popular trend in the future. Its main advantage is that it does not need to consider the interface level and impedance problems, and the interface is flexible and has stronger anti-interference capabilities. The transmission of digital sound signals through the spdif interface has become a common feature of the next-generation PCI sound card.
A. spdif is a transmission channel.
First of all, we need to explain that, do not think that the use of spdif transmission AC-3 signal is AC-3 decoding, currently there is no civil sound card products can support the hardware level of Dolby Digital decoding, the function of spdif at this time is to transmit the digital AC-3 signal from the sound card to the decoder. Those six-channel products are the product of simulating 5.1 and software decoding.
B. Relationship between digital speakers and digital sound cards
Next, you may not be clear about the principle of using the coaxial spdif out to connect a digital speaker to achieve pure digital audio playback. Next, I will give a brief introduction. As mentioned above, the digital analog conversion of the sound card is done by the Codec Chip. However, there are still serious electromagnetic waves in our computer chassis, and the conversion of D/A and A/D is still subject to severe signal interference. Many professional audio recording cards generally use the codec external approach to convert the data touch part and various external interfaces into an external box to improve the sound quality. However, the direct consequence of this is that the cost is greatly increased, and the multimedia market at home must be very high. Is there any way to make things affordable? Some speaker manufacturers have come up with a solution to transfer the D/A conversion from the sound card to the speaker. The digital multimedia speaker came into being, creative fps2000 digital and sound works 2.1digital belong to this type. The basic principle of this solution is that the sound signal is directly transmitted to a digital speaker in the PCM format using the coaxial spdif out on the sound card without being converted by the sound card Codec Chip, decode the SDK using the built-in D/A converter and then enlarge the output. As a result, the signal-to-noise ratio is naturally improved as interference decreases. However, at present, the main disadvantage is that the current digital speaker's D/A conversion unit, amplifier, speaker quality is not high, resulting in digital transmission advantages cannot be perfect.
C. digital playback of records
Color Difference output
Chromatic Aberration signals y, r-y, and B-y are generally called Y, Cr, and CB. Traditionally, Y, Cr, and CB are digital (PCM) chromatic aberration signals, the simulated color difference signal is Y, PR, and Pb. Therefore, we often see y, Cr, and CB inside the DVD player, while the output color difference is Y, PR, PB or YUV; YUV is the general name of the color difference signal in the European television system pal, including numbers and analog color difference signals are called YUV, so when you see YUV, you need to think of it as the Y, r-y, B-y signals in the PAL system. It may be a digital (PCM) YUV, it may also be a simulated YUV.
TV signals are all YUV...
: The original TV signal was black and white, and later it was colored,
: Therefore, black and white TVs only receive y signals.
: After the color receives the y Brightness Signal, it also receives the UV color signal.
: In addition, on the computer, most players are decoded to YUV display. Most of them are in yuy2 format.
: If your video card supports YUV overlay mode display, it will be decoded into the corresponding YUV format display.
: If not, convert it to RGB display.
S-video
The full name of S-video is separate video. To achieve better video effects, people began to explore a video transmission method that is faster, better, and clearer, this is the current day-to-day s-video (also known as the binary video interface). The significance of separate video is to separately transmit the video signal, that is, the color signal C and Brightness Signal y are separated based on the avinterface, and then transmitted through different channels respectively, it appeared concurrently in the late 1990s S and generally used standard 4-core (without sound effects) or extended 7-core (with sound effects ). Video devices with the S-video interface (for example, analog video capture/editing card TV sets, quasi-professional monitor TV cards/TV boxes, and video projection devices) are currently quite common, compared with the AV interface, because it no longer performs y/C hybrid transmission, it does not need to perform bright color separation and decoding, moreover, image distortion caused by Signal Crosstalk in video devices is largely avoided by using independent transmission channels, which greatly improves the image definition, however, S-video still needs to mix the two-way color difference signal (cr cb) into one-way color signal C for transmission and then decode it into CB and Cr in the display device for processing, this will still result in distortion due to certain signal losses (this distortion is very small but can still be found during tests on Strictly broadcast-level video devices ), in addition, the bandwidth of the color signal is also limited due to the mixing of Cr CB. Although S-video is already excellent, it is far from perfect. Although S-video is not the best, however, considering the current market conditions and other factors such as the overall cost, it is also the most common video interface.
YUV
TV transmission terms, a Brightness Signal (Y), two chromatic aberration signals (u, v)
YUV (also known as ycrcb) is a color encoding method used by European television systems (PAL ). YUV is mainly used to optimize the transmission of color video signals, so that it is backward compatible with vintage black and white TVs. Compared with RGB video signal transmission, RGB requires three independent video signals to be transmitted at the same time ). "Y" indicates the brightness (luminance or Luma), that is, the gray scale value, while "u" and "V" indicate the color (chrominance or chroma ), it describes the image color and saturation, and is used to specify the color of a pixel. The "brightness" is created through the RGB input signal by overlapping specific parts of the RGB signal. "Color" defines two aspects of color-tone and saturation, expressed by Cr and CB respectively. Cr reflects the difference between the red part of the GB input signal and the brightness value of the RGB signal. CB reflects the differences between the blue part of the RGB input signal and the brightness value of the RGB signal.
In Modern Color TV systems, a three-pipe color camera or a Color CCD (DOT coupler) camera is usually used to obtain the color image signal after color separation and amplification correction respectively, after the matrix conversion circuit, the Brightness Signal y and two chromatic aberration Signals R-y and B-Y are obtained. Finally, the sender encodes the brightness and chromatic aberration Signals respectively and sends them out through the same channel. This is our commonly used YUV color space.
YUV (ycrcb) And
The sample format of the Brightness Signal y and red/Blue signals. in DV, NTSC is, And pal is. note: Is not a blue difference signal sampling of 0, but a doubling of the color difference sampling frequency in the horizontal direction compared, in the vertical direction, the CR/CB interval is used to reduce the color difference by half.
The YUV signal refers to the expression of analog signals in color videos.
We know that color signals can be expressed in triplicate or synthesized. The YUV signal is actually a triplicate expression.
Among them, Y is the brightness signal, which should be a baseband signal; u and v signals, as the landlord said, are the color signals obtained from the red signal minus the Brightness Signal, and the color signal obtained by subtracting the brightness signal from the blue signal. U and V are not baseband signals, and they are orthogonal modulated.
After calculation, the three-part YUV can restore R (red), g (green), and B (blue ).
As for hd yuv, I think it is relative to SD YUV.
About ypbpr and YCbCr
Questions about the component interface have been repeatedly raised by netizens, although there have been many discussions in the past. The key to the problem is that the identifier of the component interface is repeatedly misused by some vendors, leading to confusion and confusion in the identification of common consumers.
I. Current market status
Currently, there are roughly three Representation Methods on the market:
1. Separate the line-by-line component terminals and line-by-line component terminals. In this case, YCbCr is used to represent the barrier component terminal, and ypbpr is used to represent the row-by-row component terminal.
2. The sub-terminal is shared with the sub-terminal. The sub-terminal is marked as ypbpr/YCbCr, both the line-by-line component signal and the line-by-line component signal are transmitted from this port (input ).
3. The sub-terminal is shared with the sub-terminal. The sub-terminal is marked as ypbpr. According to the specification, both the line-by-line component and the line-by-line component are output from this port (input ).
Only the third case of the above identifiers is correct. Both 1 and 2 are incorrect. But why are the manufacturers still making such mistakes? We will analyze the cause of this error. For ease of understanding, we will first briefly introduce the color space of digital TV.
Ii. Color Space of digital TV
The color space of the digital TV is different from that of the computer, not the RGB space, but the YUV space of a Brightness Signal (Y) and two chromatic aberration SIGNALS (R-y, B-Y) or YCbCr space. Digital TV uses YUV (YCbCr) color space is mainly to reduce data storage space and data transmission bandwidth, while also very convenient compatible with black and white TV (R-Y and B-Y signal 0 ). YUV (YCbCr) space and RGB space can be converted to each other. The conversion formula is as follows:
Y = 0.299 R + 0.587G + 0.114 B
CB =-0.1687 R-0.3313G + 0.5 B + 128
Cr = 0.5 r-0.4187G-0.0813 B + 128
You can also:
R = Y + 1.402 (Cr-128)
G = Y-0.34414 (CB-128)-0.71414 (Cr-128)
B = Y + 1.772 (CB-128)
From the above we can see that the entire YUV (YCbCr) color space does not involve ypbpr. When the row-by-row dvdserver has not appeared before, almost all the component terminals of the dvdserver with component output are marked as YCbCr! Because the color space of the images stored on a DVD disk is YCbCr, everything seems reasonable. However, this has laid the root of conceptual confusion in the future. Just as some vendors like to uniquely identify the sterminal as the Y/C terminal, The YCbCr logo has been used without any problems until one day, the row-by-row DVD machine appeared, manufacturers are difficult to identify the line-by-line component terminals. They finally saw a terminal marked as ypbpr in the U.S. market. For example, they picked up a life-saving straw in the ocean, so they had the confusion of the logo described at the beginning of this article.
3. Adjust the order
The YUV (YCbCr) color space of Digital TVs is defined by ITU. However, the component interfaces, especially the analog component interfaces, are not standardized internationally, at present, the most common are the dterminals in Japan, scart terminals in Europe and three-line terminals in the United States. China is currently using the United States three-line terminal, this terminal is set by the U. S. EIA (Electronic Industry Association) Standard EIA-770.2a, according to this standard, down to I, the signal up to P is transmitted using this terminal, and there is no line-by-line or line-by-line signal. In fact, the dterminals in Japan and scart terminals in Europe are also line-by-line. The dterminal's D1 to D5 logo is different but only tells the user that this machine can only output (input) A signal in the following format (for example, D4 indicates that 720p and below are supported ).
Therefore, YCbCr represents the color space and digital interface of digital TV (video), which is an international standard. Ypbpr represents only the analog video component interface and only the American Standard (including other countries that adopt the American Standard ).
YCbCr
Just as the coordinate space is used to describe the coordinate set in ry, the color space is used to describe the color set in mathematics. The common three basic color models are:
RGB, CMYK, and YUV.
YCbCr is part of the ITU-r bt1601 recommendation during the development of the world's digital organization video standards. It is actually a version of YUV through scaling and offset. Among them, Y has the same meaning as Y in YUV. CB and Cr both refer to colors, but they only differ in the representation methods. In the YUV family, YCbCr is the most widely used member in computer systems. It is widely used in many fields and adopts JPEG and MPEG formats. Generally, YUV refers to YCbCr. YCbCr has many sampling formats, such as 4: 4: 4, 4: 2: 2, 4: 1: 1 and 4: 2: 0.
Ypbpr
Ypbpr separates analog y, Pb, and PR signals and uses three cables for independent transmission, ensuring the accuracy of color reproduction.
The ypbpr interface can be seen as an extension of the S terminal. Compared with the S terminal, it needs to transmit more PB and PR signals, avoiding the process of two-way chromatic aberration mixed decoding and re-separation, it also maintains the maximum bandwidth of the chromium channel, and can be restored to RGB three primary color signals after the inverse matrix decoding circuit, this minimizes the video signal channel between the video source and the display imaging, avoids the image distortion caused by the tedious transmission process, and ensures the accuracy of color reproduction, currently, almost all large screen TVs support chromatic aberration input.
YCbCr indicates the barrier component Terminal
RGB (red, green, blue)
Color = R (red percentage) + g (Green percentage) + B (blue percentage)
When the three base colors are added to the same amount, the values are white. When the values of the same red and green are added to the same amount, the values are yellow. When the values of the Red and Green are 0, the values are red; when the same amount of green blue is added and the red value is 0, the blue is obtained. Therefore, cyan, magenta, and yellow are two colors. Red + cyan = green + Magenta = blue + yellow = white. The colors are red, green, and blue, respectively. A color image can be viewed as composed of many points. A single point in an image is called a pixel. Each pixel has a value called a pixel value, which indicates the intensity of a specific color. A pixel value is usually represented by three components: R, G, and B. For 16 standard colors of standard VGA (video graphics array) adapter card Code 0-15. In the table, the colors represented by code 1-6 are relatively dark, which are produced by half of the maximum light intensity value, and 9-15 are generated by the maximum light intensity value.
The cathode ray tube CRT (cathode ray tube) used for television sets and computer monitors is an active object. The CRT uses three electron guns to generate red, green, and blue wavelengths of light respectively, and produces colors based on different relative strengths, combining these three light waves to produce specific colors is called the addition and mixing model, which is called the RGB addition model. Adding and Mixing colors is the basic method for defining colors in computer applications. Theoretically, any color can be mixed with three basic colors in different proportions. The stronger the light intensity of the three colors, the more light we get into our eyes. The different proportions of the three colors mean different colors. If we don't get the light, it means the darkness. When the three base colors are added according to different intensity, the total light intensity is enhanced, and any color can be obtained. The relationship between a color and the three colors can be described in the following formula:
The VGA interface is the interface that outputs analog signals on the video card. The VGA (video graphics array) interface is also called the D-sub interface. Although the LCD can directly receive digital signals, many low-end products use the VGA interface to match the VGA Interface graphics card. VGA interface is a type D interface, which has 15 blank pins and is divided into three rows, five in each row. VGA interfaces are the most widely used interfaces on graphics cards. Most graphics cards use this interface.
Currently, most computers and external display devices are connected through a simulated VGA interface. The computer displays image information in digital mode, the digital/analog converter in the video card is converted into three primary color signals (R, G, and B), line and field synchronous signals, and the signals are transmitted to the display device through cables. For analog display devices, such as analog CRT display, the signal is directly sent to the corresponding processing circuit, and the driver controls the picture tube to generate an image. For LCD, DLP, and other digital display devices, the corresponding A/D (analog/digital) converter must be configured in the display device to convert analog signals to digital signals. After D/A and A/D2 conversions, some image details are inevitably lost. VGA interface is applicable to CRT display, but it is used to connect LCD and other display devices, the loss of the image during the conversion process will slightly decrease the display effect.
A vga cable is required. The interfaces on both sides are the same, because the VGA interfaces of the TV and the VGA interfaces of the video card are the same.
The information processed by the video card is eventually output to the display card. The output interface of the video card is a bridge between the computer and the display card. It is responsible for outputting the corresponding image signal to the display card. The CRT display can only accept analog signal input for design and manufacturing reasons, which requires the video card to be able to input analog signals. The VGA interface is the interface that outputs analog signals on the video card. The VGA (video graphics array) interface is also called the D-sub interface. Although the LCD can directly receive digital signals, many low-end products use the VGA interface to match the VGA Interface graphics card. VGA interface is a type D interface, which has 15 blank pins and is divided into three rows, five in each row. VGA interfaces are the most widely used interfaces on graphics cards. Most graphics cards use this interface.
Wxga
Wxga: The full name is wide extended graphics array, which is equivalent to 1280x800 () pixels, and so on.
There are many screen types in the notebook. XGA is currently the most widely used screen. Generally, it supports 1024*768. If you don't want the font to be too small, this resolution is enough. Wxga is a wide-screen version of XGA. It uses 1280*800 resolution, and the angle of view is wider than that of XGA.
There are many types of current screens, and XGA and wxga are two types of products that can be seen frequently. Some of them, such as sxga, are ultra-high-resolution screens, it is generally used by relatively high-end laptops. uvga is the most expensive one on the screen and provides the highest resolution. This is applicable to a few ultra-high-end large screen laptops.
In terms of wide screens, many readers will find screens cut at and. The former is called wxga screens, which are common in wide screens. The screens cut at are called wxga +, in addition, there is also a high-resolution wide screen called wuxga, the cost is too high, the display is naturally less machine-used.
In addition to the resolution provided by a display, the quality of a display screen also depends on the brightness of the screen. For example, some screens can provide nits brightness, there are some dazzling screens with full colors as highlights, or wide-angle wide screens that give a more comfortable effect to human perspectives. The advantages of these screens are undeniable, however, on the other hand, there are also drawbacks, such as high-brightness screens will increase due to the increase in brightness and the consumption of power will shorten the battery use time, the screen of the wide-screen laptop makes the length of the body too large and is relatively difficult to protect on the mobile, so readers should make a choice according to their own needs when purchasing.