Means the range of 0 to 10 MHz frequency. To generate or convert images. In television technology, also known as the television signal frequency, accounting for the 0 to 6 MHz bandwidth. Widely used in television, video camera, radar, computer Monitors in.
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No. 2
视频
English name: video
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Introduction to video-related
Video (English, video, and video translation) refers to a series of still images to electrical signal means to capture, record, process, store, transmit, and reproduce a variety of techniques. The image changes continuously for more than 24 frames per second (frame) picture above, according to the principle of persistence of vision, the human eye can not distinguish single static image, appears to be smooth and continuous visual effects, this screen is called a continuous video. Video also refers to the new exchange, communication tools, is one of the Internet-based equipment and software, the user can see each other's appearance via video, to hear each other's voices. Is the prototype videophone. Video technology was first developed for television systems, but now even more development for a variety of different formats to facilitate the consumers to record video. Advanced network technology also contributed to the documentary video segments to exist in the form of streaming media over the Internet and received by the computer and play. Video and film are different technologies, which is the use of photography to capture the dynamic image as a series of still photos. video (derived from the Latin "I saw") are usually referential variety of moving image storage format, such as: digital video formats, including dvd, quicktime, and mpeg-4; and analog videotapes, including vhs and betamax. Video can be recorded and transmitted via different physical media: in the video was shot or radio transmission of electrical signals, and recorded on magnetic tape, compared with the signal. Video quality is actually with the shooting and capture, and storage methods and the way change. Such as digital television (dtv) is a recently developed format, with a standard higher than the previous definition, is becoming a new standard for national television broadcast. In the UK, Australia, New Zealand, video referential term is usually informal and VCR tapes. The significance of the text before the article can be judged.
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Video streaming features
Frame rate Chinese frame rate often translated as "frame rate" or "frame rate" refers to the video format the number of static images per second playback. The typical frame rate of the early 6 or 8 per second (frame per second, referred to as fps), to the present 120 per second range. pal (Europe, Asia, Australia, the television broadcast format) and secam (France, Russia, parts of Africa and other places of television broadcasting format) provides the update rate of 25fps, and ntsc (U.S., Canada, Japan, the TV broadcast format) provides that the update rate of 29.97 fps. Movie film is based on the slower 24fps shooting, which makes national television broadcast film showing the need to convert some complex procedures (see telecine conversion). To achieve the most basic effect of persistence of vision about the speed of 10fps. Interlaced scanning and progressive scanning Video may be staggered or progressive scan to scan transmission. Interlaced scanning is underdeveloped early broadcast technology, bandwidth is very low when used to improve the quality of the method. (The technical details refer to its main entry). ntsc, pal are all interlaced scanning format with secam. In the video resolution which is often abbreviated to i to represent the interlaced scanning. For example, pal format resolution is often written as 576i50, including 576 on behalf of the number of vertical scan lines, i interlaced scanning representatives, 50 representatives of 50 per field (half of the screen scan lines). In progressive scan systems are updated each time the screen will refresh all of the scan lines. This method is more bandwidth-consuming but the screen flicker and distortion can be reduced. To the original video format for interlaced scanning (such as dvd or analogue television) into a progressive scan display device (such as lcd TV, plasma TV, etc.) acceptable format, and many display devices are equipped with a playback device or to staggered process. However, due to restrictions on cross features signal itself, can not be achieved with de-interlacing and progressive scanning the original picture is the same quality. Video Resolution More video resolution specifications of TV screen size is called "resolution." Digital video is measured in pixels, while the analog video to the number of horizontal scan lines is measured. Standard-definition video resolution No. 720/704/640x480i60 (ntsc) or 768/720x576i50 (pal / secam). The new high-definition television (hdtv) resolution up to 1920x1080p60, each horizontal scan lines that are 1920 pixels, each frame has 1080 scanning lines, 60 frame per second speed of play. 3d video resolution with voxel (volume picture element, Chinese translated as "voxels") to represent. For example, a 512 × 512 × 512 voxels resolution, for a simple 3d video, can be included computer equipment, including some pda player. Aspect Ratio Traditional television (green) and the common comparison of the film screen aspect ratio aspect ratio (aspect ratio) is used to describe the elements of the video screen and the screen ratio. Conventional TV screen aspect ratio of 4:3 (1.33:1). hdtv aspect ratio of 16:9 (1.78:1). The aspect ratio of 35mm film negatives about 1.37:1. Although most of the pixels on the computer screen as a square, but pixels digital video is usually not the case. For example, pal and ntsc signals used in digital preservation format ccir 601, and its corresponding non-peer wide-screen format. So to 720x480 pixel images recorded ntsc dv specifications may be because it is relatively "thin" the pixel format in the show when a 4:3 picture, pixel format, or vice versa because the more "fat" and become 16:9 screen. Color space and the amount of pixel data uv color plate examples, where y = 0.5 color space (color space) or the color model (color model name) provides a description of the video which color way. For example, the use of yiq ntsc TV model, which uses yuv pal model, secam used ydbdr model. Among the digital video pixel data volume (bits per pixel, for short bpp) which represents each pixel can display many different colors of capacity. As the bandwidth is limited, so designers often borrow from the chroma sampling techniques like the demand to reduce the bpp. (Eg 4:4:4, 4:2:2, 4:2:0). Video quality Video quality (or translated as "quality", "image quality") can take advantage of objective PSNR (peak signal-to-noise ratio, psnr) to quantify, or by observation by experts to conduct subjective video quality of assessment. ● for a video processing system (such as compression algorithms or transmission system), the typical subjective quality assessment typically includes the following steps: ● _Select_ a group of raw video clips (called src) as the baseline. ● _Select_ the processing or transmission system _set_tings (called hrc). ● How to _set_ the video will be processed and presented to the evaluator to collect their evaluation of the scientific method. ● invite a sufficient number of evaluators, usually not less than 15 people. ● implementation of the assessment. ● calculated for each assessor to give each of the dozen different hrc score (usually averaged). In itu-t recommendations bt.500 which describes the many kinds of subjective quality assessment methods. One standard approach is dsis (double stimulus impairment scale). In dsis assessment, the assessor will first watch a video clip untreated, treated and then watch the video clips. Finally, for the processed video clips to make evaluations, from "not tell the difference between the original image" to "serious deterioration compared with the original image." Video compression technology (digital signal only) Since the digital signal system is widely used, people developed many methods to compress the video stream. As the video data includes a space and time redundancy, it makes the uncompressed video stream to send the efficiency point of view is quite bad. Overall, the spatial redundancy can be borrowed from the "record only single-frame part and another part of the difference" to reduce; This technique is known as intraframe compression (intraframe compression). And is closely related with the image compression. And time redundancy can be borrowed from the "record only two differences between the different screens," to reduce; This technique is known as interframe compression (interframe compression), including motion compensation and other technologies. The most commonly used video compression technology, direct broadcast satellite television with dvd used mpeg-2, and Internet transmission used mpeg-4. Bit rate (for digital signals) Bit rate (also translated as bit rate or bit rate or bit rate) is a manifestation of the video stream in the amount of information contained in the method. The number of units of bit / s (bits per second transmitted between the number, but also written as bps) or mbit / s (millions per second between the number of bits sent, and written mbps). Higher bit rate will accommodate higher video quality. Such as dvd format video (typical bit transfer rate 5mbps) picture quality than vcd format video (typical bit transfer rate of 1mbps). hdtv format has a higher (about 20mbps) bit rate, and thus a higher quality than the dvd. Variable bit rate (variable bit rate, abbreviated as vbr) is a pursuit of quality improvement and reduce the video bit rate means. Vbr-encoded video using dynamic or complex in the large screen will automatically time to record a higher rate images, and in the rest or simply a decrease in the rate of screen time. This will ensure the premise of a constant image quality to minimize the transmission rate. However, the bandwidth for the transmission fixed, and there is no need to transmit real-time video streaming is a temporary means, constant bit rate (constant bit rate, cbr) is more suitable than vbr. Video conferencing is one example. Stereoscopic video "Stereo Video" (stereoscopic video) for about two people send the video to create a slightly different three-dimensional objects feel. As the two video images are mixed together, so that when viewing ambiguous directly or color is not correct, we must take the mask or special glasses to show its effect. This regard continuing evolution of technology is expected in late 2006 hd dvd and blu-ray disc containing both will appear three-dimensional video movie. See stereoscopy and 3-d film.
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Popular video formats
mpeg / mpg / dat is the motion picture experts group mpeg abbreviation. Such formats include mpeg-1, mpeg-2 and mpeg-4, including a variety of video formats. mpeg-1 is believed to be the most contact with us, because now it is being widely used in the production of vcd and some video clips to download the network application above, most of the vcd is mpeg1 format with compression (automatically burning software mpeg1 to. dat format), use the mpeg-1 compression algorithm, you can put a 120 minute-long film compressed to about 1.2 gb size. mpeg-2 dvd is used in the production, while in some hdtv (high definition television) and a number of demanding video editing, processing above, there are a considerable number of applications. Using the mpeg-2 compression algorithm to compress a 120 minute long movie can be compressed to 5-8 gb in size (mpeg2 to mpeg-1 and its image quality can not match). avi avi, Audio Video Interleaved (audio video interleaved) abbreviation. avi video released by Microsoft in this format in the video field has been in existence for several years in a row. avi format called convenience, image quality is good, but the disadvantage is that the file size too large. ra / rm / ram rm, real networks developed by the company's audio / video compression standards in a real media, real player can do is use internet resources for these technical specifications in line with real media audio / video live. In the real media file specification includes three types: realaudio, real video and real flash (real networks with macromedia's launch of a new generation of high compression ratio animation format). real video (ra, ram) format from the beginning is positioned in the video streaming applications, it can be said that the founder of video streaming technology. It can use the 56k modem dial-up conditions for uninterrupted video playback, but its image quality is less capable than the vcd, rm if you read those discs can be significantly compressed compared out. Friends used mac machine should have come in contact quicktime. apple quicktime company originally used a mac computer video image processing software. quick-time offers two standard images and digital video formats, which can support the static pic and jpg image formats, indeo dynamic compression method based on the mov and mpeg compression method based on the mpg video format. wmv If you find the original type of player suddenly open the avi file format, then you should consider is not met n avi. n avi new avi is the abbreviation of an underground organization called the shadow realm developed a new video format. It is a microsoft asf compression algorithm modified from (not imagined avi), video format is nothing more than the pursuit of compression ratio and image quality, so the navi in pursuit of this goal, improving the original asf format of some shortcomings, Let navi can have a higher frame rate. It can be said, navi is to remove features improved video streaming asf formats. rmvb
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Understanding video encoding
Common video encoding: 2, microsoft video 1 For video conferencing codec, which h.261 for isdn, ddn line, h.263 for the LAN, but most of the machines used to play this codec is not used for encoding. 5, intel indeo video 4 and 5 Obtained using this method excellent image quality, because this method is the ordinary mode of the rgb color to a more compact yuv color mode. If you want to compress the avi into mpeg-1, then use it to get results is ideal, but it's generated files too. 8, divx - mpeg-4 low-motion/fast-motion In fact, divx, original divx asf to break microsoft's specifications developed, now transformed into divxnetworks company development team, so has introduced a new version, the biggest feature is added in the encoding process 1-pass and 2 - pass the equivalent of twice _set_ting ,2-pass encoding, in order to maximize the network bandwidth and visual effects in the balance.
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视频格式转换
The common video formats currently nothing more than two categories: 1, the image format (video); 2, streaming media format (stream video). In the image format can also be divided into three types according to the source: 1, avi format: This is Microsoft (microsoft) made a "long history" of a video format; 2, mov format: This is the apple (apple) the company made a video format; 3, mpeg / mpg / dat: This is by the International Organization for Standardization iso (international standards organization) and iec (international electronic committee) jointly developed a format for encoding video. mpeg moving image compression algorithm is the international standard, is now almost common support for all computer platforms. In the same streaming media formats can also be divided into three types: 1, rm format: This is the real networks has developed a new type of streaming video file format. 2, mov format: mov file can also be used as a streaming format. quicktime can provide real-time via internet digital information flow, work flow and file playback, in order to adapt to the network multimedia applications, quicktime for a variety of popular browser software provides a corresponding quicktime viewer plug-ins (plug-in), can browser, multimedia data in real-time playback. 3, asf format: This is a streaming media format developed by Microsoft, is a real-time dissemination on the internet multimedia technology standard. If you want to learn more about a variety of video formats, you can see what relevant information, this is not explained in detail. Understand now several major video formats, video format conversion from say the problem is much simpler, in fact, more than a few video formats into each other only. The more common video format conversion are: dat-> mpeg1 dvd-> mpeg2 mpeg1-> mpeg2 mpeg-> mov For example, make a vcd (mpeg1 is encoded video files) can be made into a movie online watch, the biggest bottleneck is that the file size changes, and to be able to adapt to the characteristics of the network, so that it can not meet the original format necessary, must be converted into standard Internet streaming video format can, for example, is rm or asf, this is necessary, so for video format conversion software for streaming media format and students will apply, and there are now very popular mpeg4 video compression technology, it is able to compress a dvd to a cd up, and video effects will not be much change, at least in the ordinary user's perspective is very good, and the file size is greatly reduced a, which requires to convert mpeg4 files to dvd software there, but if someone wants to rm convert mpeg1 (vcd), not much practical significance, because this does not give effect to bring the video too large increase, but much larger file size, so it is rarely able to see this transformation of the software, the other is similar, so in the field of video conversion, you can refer to the following two principles: Here, basically a brief introduction into the finished video content, and the rest say is that some of the relevant conversion tool, I do not want to say anything, because their use of tools is a benevolent see benevolence and the wise see wisdom in the things But now I have seen some of the tools are basically abroad, the text is not very good for e users, is really a headache, but now well-known developer of multimedia software company launched a hero a comprehensive tool for video format conversion software "Hero Video through 2.0", its most prominent feature is: I think that is enough to attract these two points into the needs of many users to try. Well, stop here, and I think through this article, we will in the future transformation of the targeted video and make their own video files. Is it no other way to get the mpeg4 encoding format film it? No, as long as you install the divx codec to install the mpeg4 encoder can, through some of the video encoding software by calling the mpeg4 encoder mpeg4 to make your own movie, Hero's video pass through 2.0 to complete this work in mpeg4 coding, there are two options for the choice of encoding, of course, is the most common and most commonly used is the fast-motion and low-. Put a dvd into an mpeg4 movie and cd to put on, before the conversion, will consider the converted file is to put a cd on a cd or two, the general approach is to consider regulating code rate and thus control the file size to achieve, then this is the case, the encoding process is not able to adjust the rate is fixed, that is, with a fixed rate (crb) to achieve, such as bit rate is _set_ to 1000k, then the entire coding process, it has maintained 1000k bit rate to encode, which is divx :-) mpeg-4 low-motion, for example, is a 1150k bitrate vcd achieved. Know the difference between the two appears to divx :-) mpeg-4 low-motion than divx :-) mpeg-4 fast-motion better, and it is not true, that depends on the direction of a specific application, For example, to be applied to the network, then use the divx :-) mpeg-4 fast-motion like some, half the file size small, but at the expense of some picture quality, but said in the past, as well as into if we want to vcd mpeg4 files, then use the divx :-) mpeg-4 low-motion is inappropriate, file size basically has not changed, but the video quality is no fundamental change, but if we want to convert dvd mpeg4 files, then use the divx: -) mpeg-4 low-motion on the most appropriate, the file size greatly reduced, and video quality than the dvd is not much difference, if you want engraved on the cd, then there are two cd on it, and the code rate is still _set_ to 1200k of effect, a cost-effective too.
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All video formats
New types of digital video: atsc (advanced television systems committee), common in North America dvb (digital video broadcasting), common in Europe, Southeast Asia, Africa, South America isdb (integrated services digital broadcasting), common in Japan Analog Video: mac (in Europe - has been eliminated) ntsc (North America, part of the South Central America, Japan, Taiwan) pal-m (Brazil), this is the pal of the deformation av terminal (1 _set_ of rca or bnc) s terminal (s representatives separated video, 1 _set_ of mini-din connector) hdmi (use of new digital home appliances digital video terminal). hdcp mandatory features for the c terminal (concelman connector) iec 169-2 (most common in the United Kingdom) uhf terminals (such as pl-259/so-239) [Analog tape formats (see analog television)] u-matic (sony) betacam sp vcr, vcr-lp, svr vhs-c (jvc) video hi8 [Digital tape formats (see digital video)] d1 (sony) d2 (sony) d3 d4 d5 hd digital betacam (sony) betacam imx (sony) hdv dv digital8 (sony) Laser Disc (laserdisc, mca and Philips) hd dvd (Hitachi and Toshiba) m-jpeg (iso) mpeg-4 (iso) h.264/mpeg-4 avc (itu-t + iso)
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视频串流特性
Interlaced scanning and progressive scanning To the original video format for interlaced scanning (such as DVD or analog TV broadcasts) to progressive scan display device (such as LCD TV, plasma TV, etc.) acceptable format, and many display devices are equipped with a playback device or to staggered process. However, due to restrictions on cross features signal itself, can not be achieved with de-interlacing and progressive scanning the original picture is the same quality. 3D video resolution to voxel (volume picture element, Chinese translated as "voxels") to represent. For example, a 512 × 512 × 512 voxels resolution, for the simple 3D video that can be included part of the PDA, including computer equipment broadcast. Although most of the pixels on the computer screen as a square, but pixels digital video is usually not the case. For example, in PAL and NTSC signals using a digital preservation format, CCIR 601, and its corresponding non-peer wide-screen format. So to 720x480 pixels, video recording the NTSC DV specifications may be because it is relatively "thin" the pixel format in the show when a 4:3 picture, pixel format, or vice versa because the more "fat" and become 16:9 screen. Among the digital video pixel data volume (bits per pixel, for short bpp) which represents each pixel can display many different colors of capacity. As the bandwidth is limited, so designers often borrow from the chroma sampling techniques like the demand to reduce the bpp. (Eg 4:4:4, 4:2:2, 4:2:0). ● for a video processing system (such as compression algorithms or transmission system), the typical subjective quality assessment typically includes the following steps: ● How to _set_ the video will be processed and presented to the evaluator to collect their evaluation of the scientific method. ● calculated for each assessor to give each of the dozen different HRC score (usually averaged). Since the digital signal system is widely used, people developed many methods to compress the video stream. As the video data includes a space and time redundancy, it makes the uncompressed video stream to send the efficiency point of view is quite bad. Bit rate (also translated as bit rate or bit rate or bit rate) is a manifestation of the video stream in the amount of information contained in the method. The number of units of bit / s (bits per second transmitted between the number, but also written as bps) or Mbit / s (millions per second between the number of bits transmitted, but also written as Mbps). Higher bit rate will accommodate higher video quality. Such as DVD video format (typically bit transfer rate 5Mbps) picture quality than VCD format video (typical bit transmission rate 1Mbps). HDTV format, with a higher (about 20Mbps) bit rate, and thus a higher quality than DVD. "Stereo Video" (Stereoscopic video) for about two people send the video to create a slightly different three-dimensional objects feel. As the two video images are mixed together, so that when viewing ambiguous directly or color is not correct, we must take the mask or special glasses to show its effect. Technology in this area continues to evolve, the expected end of 2006 HD DVD and Blu-ray Disc with the two sides will appear three-dimensional video movie. See Stereoscopy and 3-D film.
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Popular video formats
MPEG / MPG / DAT MPEG is the abbreviation of Motion Picture Experts Group. Such formats include MPEG-1, MPEG-2 and MPEG-4, including a variety of video formats. MPEG-1 is believed to be the most contact with us, because now it is being widely used in the production of VCD, and some video clips to download the network application above, most of the VCD format is compressed with MPEG1 (burning software automatically MPEG1 to. DAT format), use MPEG-1 compression algorithm, you can put a 120 minute-long film compressed to about 1.2 GB size. MPEG-2 is used in DVD production, while some of the HDTV (high definition television) and a number of demanding video editing, processing above, there are a considerable number of applications. Using MPEG-2 compression algorithm to compress a 120 minute long movie can be compressed to 5-8 GB in size (MPEG2 image quality with MPEG-1 can not match). AVI AVI, Audio Video Interleaved (Audio Video Interleaved) abbreviation. This AVI video format released by Microsoft in the video field has been in existence for several years in a row. AVI format called convenience, image quality is good, but the disadvantage is that the file size too large. RA / RM / RAM RM, Real Networks developed the company's audio / video compression standards in a Real Media, Real Player can do is to use Internet resources for these technical specifications meet the Real Media audio / video live. The Real Media file specification includes three types: RealAudio, Real Video and Real Flash (Real Networks to launch with a new generation of Macromedia's high compression ratio animation format). REAL VIDEO (RA, RAM) format from the beginning is positioned in the video streaming applications, it can be said that the founder of video streaming technology. It can use dial-up 56K MODEM conditions for uninterrupted video playback, but its image quality is less capable than the VCD, RM if you read those discs can be significantly compressed compared out. MOV A friend used a Mac should have come in contact QuickTime. Apple's QuickTime for Mac was originally a computer video image processing software. Quick-Time offers two standard images and digital video formats that can support static PIC and JPG image formats, Indeo compression method based on dynamic MOV and MPG based on the MPEG compression of video formats. ASF ASF (Advanced Streaming format Advanced Streaming Format). ASF is MICROSOFT and now the Real player to compete and develop out of a can watch video online file compression format. ASF uses MPEG4 compression algorithm, compression ratio and image quality is very good. Because ASF is an online real-time viewing of the video "streaming" format exists, so it's almost point image quality than the VCD is not surprising, but lower than the same video "streaming" format better RAM format. WMV If you find the original type of player suddenly open the AVI file format, then you should consider is not met n AVI. n AVI is short for New AVI, is an underground organization called Shadow Realm developed a new video format. It is by the Microsoft ASF compression algorithm modified from (not imagined AVI), video format is nothing more than the pursuit of the compression ratio and image quality, so NAVI pursuit of this goal, to improve the original ASF format of some shortcomings, so NAVI can have a higher frame rate. It can be said, NAVI is to remove features improved video streaming ASF format. RMVB FLV MP4 Common video phone
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Video Station system
Official Website: http://www.zoomla.cn/ Zoomla! Waves by the CMS development team has 10 years of experience of professionals, and form, including algorithm, foreground, WEB standards, SEO, UI and many other groups, matrix development, to build large-scale CMS platform provides a solid foundation. January 1, 2009, as a leading CMS vendors, software teams waves launched its major version - waves CMS2.X series, for the first time into the SNS, the businesses, communities, mall open computing more convenient , convenient, causing a major impact in the industry, and pioneered the corporate website "cloud" type of software development concepts and the survival of open communion ID point of view, the SNS, mall, shop, jobs, Yellow Pages, customer management, document management functions effectively Build your communion in which to promote the growth of the industry. The basic function of the camera or video transmission, it is to rely on the principle of increasing support to achieve it? The so-called video transmission is reached the screen a picture of the picture, because transmission speed quickly, so you can let everyone see the continuous dynamic of the screen, like put the movie. Generally when the number of transmission picture 24 frames per second, the screen will have a continuity. During the transmission of this picture, the picture must be compressed, like a general compression H.261, JPEG, MPEG and so on, or transmission bandwidth required becomes very large. I do not know whether we pay attention to with RealPlayer, when playing a movie, the player will have a lower transmission speed 250kbps, 400kbps, 1000kbps ... the higher picture quality, the greater the speed. The camera for video transmission is the principle, if transferred to the camera's resolution 640 × 480, to capture the image size is about 50kb each about 30 frames per second, then the camera speed is required to transmit video 50 × 30 / s = 1500kbps = 1.5Mbps. In real life, it is generally used for online video chat of a resolution of 320 × 240 or even lower, the transmission of frames to 24 frames per second. In other words, when the video transmission rate to less than 300kbps, the more people you can chat smooth video transmission. If you use a higher video compression methods, such as MPEG-1, etc., can reduce the transmission rate to less than 200kbps. This is the general video chat, network camera, the required transmission speed.
