Introduction to CIF, DCIF, and D1 formats for CIF
CIF is a commonly used standardized image format (CommonIntermediateFormat). In H. In the 323 protocol suite, the standard acquisition resolution of the video capture device is specified. CIF = 352 × 288 pixels.
QCIF stands for Quartercommonintermediateformat. QCIF is also a commonly used standardized image format. In H. In 323, it is specified that QCIF=176×144 pixels.
The CIF format has the following features:
(1) The spatial resolution of the TV image is the resolution of the Video Home System (VHS), which is 352×288.
(2) Use non-interlaced scan.
(3) Using the NTSC frame rate, the maximum frame rate for television images is 30000/1001≈29.97 frames/sec.
(4) Use 1/2 PAL horizontal resolution, ie 288 lines.
(5) The luminance and the two color-difference signals (Y, Cb, and Cr) components are coded separately, and their values ​​range with ITU-RBT. 601. That is, black=16, white=235, the maximum value of the color difference is equal to 240, and the minimum value is equal to 16.
The following is a description of the parameters of the five CIF image formats. The order of the parameters is "the number of pixels in the image format luma sample (dx) the number of luma samples (dy) the number of chroma samples (dx/2) the number of chroma sample lines (dy/2)".
sub-QCIF128×966448
QCIF176×1448872
CIF352×288176144
4CIF704 × 576352288 (that we often say D1)
16CIF1408×1152704576
At present, Qcif (176×144), CIF (352×288), HALFD1 (704×288), and D1 are mainly used in the wireless video surveillance industry.
(704 × 576) and other resolutions, CIF recording resolution is the mainstream resolution, most products are using CIF resolution. There are four main reasons why the current market accepts CIF resolution: 1. Current digital surveillance requires that the video stream cannot be too high; 2. The video transmission bandwidth is also limited; 3. The resolution can be improved by using HALFD1, D1 resolution to meet the high quality The request, but at the cost of high streaming. At this stage, there are many D1 products, but the market share is very small; 4, using CIF resolution, SNR than 32db, the average user is acceptable, but not the ideal video image quality. At present, people in the industry are trying to use HALFD1 to find the balance between CIF and D1. However, as the capacity of a single hard disk reaches 750 GB or even 1000 GB, and most DVRs in China can already connect eight 1000 GB hard disks, D1 will gradually become the mainstream.
What is the DCIF resolution?
After research, we have found a more effective monitor video coding resolution (DCIF) with pixels of 528×384. The DCIF resolution is that the source of the video image is the odd and even two HALFD1s, which are deinterlaced to form a D1 (720*576), D1 is treated as a boundary, and becomes 4CIF (704×576), 4CIF is the level 3/ 4 reduction, vertical 2/3 reduction, converted into 528 × 384. 528 × 384 pixel number is exactly twice the number of CIF pixels, in order to distinguish from the often-called 2CIF (704 * 288), we call it DOUBLECIF, referred to DCIF. Obviously, DCIF is more balanced than HalfD1 in both horizontal and vertical directions.
Why DCIF resolution?
The digital wireless monitoring industry puts forward two requirements for digital surveillance products: First, it requires a low data volume to ensure that the system can record for a long time and stabilize the real-time network transmission; secondly, it requires high resolution playback images to meet the requirements for details. The DCIF resolution on the current hardware and software platforms can well meet the above two requirements.
HalfD1 resolution has been adopted by some products to solve the shortcomings of insufficient CIF definition, high D1 storage, and high price. However, since he only improves the horizontal resolution relative to CIF, the image quality improvement is not particularly noticeable, but the code stream increases greatly.
After testing a large number of video signals, based on the current video compression algorithm, DCIF resolution is better than HalfD1 can solve the shortcomings of CIF sharpness is not enough and D1 storage is high, the price is high, to solve the CIF and 4CIF, especially in With a 512Kbps bit rate, stable high-quality images can be obtained, satisfying users' requirements for higher image quality, and providing better options for video encoding.
The resolution of CIF definition is not high enough and the D1 storage is high and the price is high. The resolution of the static playback resolution is up to 360TVline in theory, which exceeds the image level of the standard VHS tape recorder 280TVline in the analog monitor and reaches the Ministry of Security Industry. The clarity requirements of the video standard Level 2 and Level 3 projects meet the requirements of most wireless video surveillance.
What is D1?
As a closed-circuit television monitoring system for a long time, we all think that D1 is a DVR display, video, playback resolution, in fact, not, D1 is the digital TV system display format standards, are divided into the following five kinds of specifications:
D1: 480i format (525i): 720 × 480 (horizontal 480 lines, interlaced), the same as NTSC analog TV resolution, line frequency is 15. 25kHz, equivalent to what we call 4CIF (720 × 576)
D2: 480P format (525p): 720 × 480 (480 lines of horizontal, progressive scan), compared to the D1 interlaced scanning to clear a lot, and progressive scan DVD specifications, line frequency 31. 5kHz
D3: 1080i format (1125i): 1920 × 1080 (1080 horizontal lines, interlaced scanning), the most high-definition resolution using a resolution of 1920 × 1080i/60Hz, line frequency of 33. 75kHz
D4: 720p format (750p): 1280 × 720 (horizontal 720 lines, progressive scan), although the resolution is lower than the D3, but because of progressive scan, more people on the market feel relative to 1080I (actual 540 lines successively) Visual effects are clearer. However, personal feeling, in the case of the maximum resolution of 1920 × 1080, D3 feels more clear than the D4, especially the text performance, the resolution is 1280 × 720p/60Hz, line frequency is 45kHz
D5: 1080p format (1125p): 1920 × 1080 (1080 horizontal lines, progressive scan), the highest standard for civil high-definition video, resolution of 1920 × 1080P/60Hz, line rate of 67. 5KHZ.
The D1 and D2 standards are the highest standards of our general analog television, and can not be called high-definition. The D3 1080i standard is the basic standard of high-definition television. It can be compatible with the 720p format, and the D5's 1080P is only a professional standard. Not civil class, the above given 60HZ is only the ideal field frequency, and its line rate is 67. 5KHZ, there is currently no such high-frequency TV is available, in the field of professional 1080P field frequency Only 24HZ, 25HZ and 30HZ.
It should be pointed out that the D-terminal is a unique interface unique to Japan. Domestic TVs have almost no such interface, and the most is the color-difference interface, while the color-difference interface supports up to D4. In theory, there is certainly no HDMI (pure digital signal, The maximum resolution is up to 1080P), but there is usually no big difference in the resolution below 1920:1080.
What resolution does the domestic mainstream DVR (Digital Video Recording) use? How to calculate the hard disk capacity?
Currently, the mainstream DVRs in China use two resolutions: CIF and D1.
The number of common hard disk recorders is 1, 2, 4, 8, 9, 12, and 16. It can connect up to 8 2000GB hard disks with a total capacity of up to 1. 6T (currently the largest hard disk on the market is around 1000GB). If CIF resolution is used, the capacity of each hard disk is usually 180MB~250MB/hour. Under the value of 200MB / hour; if the resolution of D1 requires an hourly video recording capacity of 720MB ~ 1000MB / hour, under normal circumstances in order to reduce the hard disk capacity can be calculated in accordance with 500MB / hour, the frame rate smart settings less than 25fps , Streams are also less! I believe we can figure out how long it takes to record a full 16-channel hard disk video recorder with 500GB of 500GB.
Calculation example: 8-way CIF format 24 hours of continuous video recording 30 days required hard disk capacity?
8 ways × 200M × 24 hours × 30 days ÷ 1024M = 1125G (Note: 1G = 1024M)
CIF is a commonly used standardized image format (CommonIntermediateFormat). In H. In the 323 protocol suite, the standard acquisition resolution of the video capture device is specified. CIF = 352 × 288 pixels.
QCIF stands for Quartercommonintermediateformat. QCIF is also a commonly used standardized image format. In H. In 323, it is specified that QCIF=176×144 pixels.
The CIF format has the following features:
(1) The spatial resolution of the TV image is the resolution of the Video Home System (VHS), which is 352×288.
(2) Use non-interlaced scan.
(3) Using the NTSC frame rate, the maximum frame rate for television images is 30000/1001≈29.97 frames/sec.
(4) Use 1/2 PAL horizontal resolution, ie 288 lines.
(5) The luminance and the two color-difference signals (Y, Cb, and Cr) components are coded separately, and their values ​​range with ITU-RBT. 601. That is, black=16, white=235, the maximum value of the color difference is equal to 240, and the minimum value is equal to 16.
The following is a description of the parameters of the five CIF image formats. The order of the parameters is "the number of pixels in the image format luma sample (dx) the number of luma samples (dy) the number of chroma samples (dx/2) the number of chroma sample lines (dy/2)".
sub-QCIF128×966448
QCIF176×1448872
CIF352×288176144
4CIF704 × 576352288 (that we often say D1)
16CIF1408×1152704576
At present, Qcif (176×144), CIF (352×288), HALFD1 (704×288), and D1 are mainly used in the wireless video surveillance industry.
(704 × 576) and other resolutions, CIF recording resolution is the mainstream resolution, most products are using CIF resolution. There are four main reasons why the current market accepts CIF resolution: 1. Current digital surveillance requires that the video stream cannot be too high; 2. The video transmission bandwidth is also limited; 3. The resolution can be improved by using HALFD1, D1 resolution to meet the high quality The request, but at the cost of high streaming. At this stage, there are many D1 products, but the market share is very small; 4, using CIF resolution, SNR than 32db, the average user is acceptable, but not the ideal video image quality. At present, people in the industry are trying to use HALFD1 to find the balance between CIF and D1. However, as the capacity of a single hard disk reaches 750 GB or even 1000 GB, and most DVRs in China can already connect eight 1000 GB hard disks, D1 will gradually become the mainstream.
What is the DCIF resolution?
After research, we have found a more effective monitor video coding resolution (DCIF) with pixels of 528×384. The DCIF resolution is that the source of the video image is the odd and even two HALFD1s, which are deinterlaced to form a D1 (720*576), D1 is treated as a boundary, and becomes 4CIF (704×576), 4CIF is the level 3/ 4 reduction, vertical 2/3 reduction, converted into 528 × 384. 528 × 384 pixel number is exactly twice the number of CIF pixels, in order to distinguish from the often-called 2CIF (704 * 288), we call it DOUBLECIF, referred to DCIF. Obviously, DCIF is more balanced than HalfD1 in both horizontal and vertical directions.
Why DCIF resolution?
The digital wireless monitoring industry puts forward two requirements for digital surveillance products: First, it requires a low data volume to ensure that the system can record for a long time and stabilize the real-time network transmission; secondly, it requires high resolution playback images to meet the requirements for details. The DCIF resolution on the current hardware and software platforms can well meet the above two requirements.
HalfD1 resolution has been adopted by some products to solve the shortcomings of insufficient CIF definition, high D1 storage, and high price. However, since he only improves the horizontal resolution relative to CIF, the image quality improvement is not particularly noticeable, but the code stream increases greatly.
After testing a large number of video signals, based on the current video compression algorithm, DCIF resolution is better than HalfD1 can solve the shortcomings of CIF sharpness is not enough and D1 storage is high, the price is high, to solve the CIF and 4CIF, especially in With a 512Kbps bit rate, stable high-quality images can be obtained, satisfying users' requirements for higher image quality, and providing better options for video encoding.
The resolution of CIF definition is not high enough and the D1 storage is high and the price is high. The resolution of the static playback resolution is up to 360TVline in theory, which exceeds the image level of the standard VHS tape recorder 280TVline in the analog monitor and reaches the Ministry of Security Industry. The clarity requirements of the video standard Level 2 and Level 3 projects meet the requirements of most wireless video surveillance.
What is D1?
As a closed-circuit television monitoring system for a long time, we all think that D1 is a DVR display, video, playback resolution, in fact, not, D1 is the digital TV system display format standards, are divided into the following five kinds of specifications:
D1: 480i format (525i): 720 × 480 (horizontal 480 lines, interlaced), the same as NTSC analog TV resolution, line frequency is 15. 25kHz, equivalent to what we call 4CIF (720 × 576)
D2: 480P format (525p): 720 × 480 (480 lines of horizontal, progressive scan), compared to the D1 interlaced scanning to clear a lot, and progressive scan DVD specifications, line frequency 31. 5kHz
D3: 1080i format (1125i): 1920 × 1080 (1080 horizontal lines, interlaced scanning), the most high-definition resolution using a resolution of 1920 × 1080i/60Hz, line frequency of 33. 75kHz
D4: 720p format (750p): 1280 × 720 (horizontal 720 lines, progressive scan), although the resolution is lower than the D3, but because of progressive scan, more people on the market feel relative to 1080I (actual 540 lines successively) Visual effects are clearer. However, personal feeling, in the case of the maximum resolution of 1920 × 1080, D3 feels more clear than the D4, especially the text performance, the resolution is 1280 × 720p/60Hz, line frequency is 45kHz
D5: 1080p format (1125p): 1920 × 1080 (1080 horizontal lines, progressive scan), the highest standard for civil high-definition video, resolution of 1920 × 1080P/60Hz, line rate of 67. 5KHZ.
The D1 and D2 standards are the highest standards of our general analog television, and can not be called high-definition. The D3 1080i standard is the basic standard of high-definition television. It can be compatible with the 720p format, and the D5's 1080P is only a professional standard. Not civil class, the above given 60HZ is only the ideal field frequency, and its line rate is 67. 5KHZ, there is currently no such high-frequency TV is available, in the field of professional 1080P field frequency Only 24HZ, 25HZ and 30HZ.
It should be pointed out that the D-terminal is a unique interface unique to Japan. Domestic TVs have almost no such interface, and the most is the color-difference interface, while the color-difference interface supports up to D4. In theory, there is certainly no HDMI (pure digital signal, The maximum resolution is up to 1080P), but there is usually no big difference in the resolution below 1920:1080.
What resolution does the domestic mainstream DVR (Digital Video Recording) use? How to calculate the hard disk capacity?
Currently, the mainstream DVRs in China use two resolutions: CIF and D1.
The number of common hard disk recorders is 1, 2, 4, 8, 9, 12, and 16. It can connect up to 8 2000GB hard disks with a total capacity of up to 1. 6T (currently the largest hard disk on the market is around 1000GB). If CIF resolution is used, the capacity of each hard disk is usually 180MB~250MB/hour. Under the value of 200MB / hour; if the resolution of D1 requires an hourly video recording capacity of 720MB ~ 1000MB / hour, under normal circumstances in order to reduce the hard disk capacity can be calculated in accordance with 500MB / hour, the frame rate smart settings less than 25fps , Streams are also less! I believe we can figure out how long it takes to record a full 16-channel hard disk video recorder with 500GB of 500GB.
Calculation example: 8-way CIF format 24 hours of continuous video recording 30 days required hard disk capacity?
8 ways × 200M × 24 hours × 30 days ÷ 1024M = 1125G (Note: 1G = 1024M)
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