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Published byErica McGee Modified over 8 years ago
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2 к DV- порту Digital video Digital video cameras allow you to shoot movies in digital format directly. Digital video is a sequence of frames with a certain resolution is stored in the video camera on magnetic tape. After you connect a digital video camera to the DV-port of the computer and launch the digital video editing made capture and copy video to your hard drive.
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3 During capture digital video editing software automatically detects changes in the images in the video stream and splits the video into smaller chunks, called scenes. User during installation can split video into scenes by time or arbitrarily. The installation of digital video is done by selecting the best scenes and placing them in a certain time sequence. Digital video
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4 When switching between scenes, you can use various animation effects: dissolve, dissolution, appearance, etc. Viewing digital video can be carried out directly on the screen of a computer monitor or on a connected TV. к DV- порту
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5 Digital video Video consists of a stream of successive frames and sound. Showing full frame and high-quality sound reproduction require transmission of very large amounts of information at a time.
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6 Digital video In the process of capture and save the video file on the disk made its compression: The methods of compressing still raster graphics and sound. Use streaming compression - in a sequence of frames allocated scenes in which the image changes slightly. Provided keyframe based on which are built following dependent frames. The dependent frames instead of passing all the pixels color codes color codes are transmitted only a small number of pixels, the ones that have changed.
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7 Digital video TV standard video playback uses frame resolution 720 Χ 576 pixels with 24-bit color depth. Playback speed is 25 frames per second. Therefore, in one second you must pass a huge amount of video data: I. = 24 bits · 720 · 576.25 = 248,832,000 bits = = 31,104,000 bytes = 30375 KB = 30 MB ·
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8 Some video formats There are many different formats of video data ( data compression methods ). In Windows, for example, more than 10 years, the format Video for Windows, based on universal files with the AVI (Audio Video Interleave - audio-video interleave ). Becoming more common lately receive video compression system, allowing some imperceptible image distortion in order to increase the compression ratio. The most famous of this class is the standard MPEG (Motion Picture Expert Group). Methods used in MPEG, not simple to understand and rely on rather complex mathematics ( standardized ). There was widespread technology called DivX (Digital Video Express). DivX has been achieved thanks to the compression ratio, which allowed vmese quality recording full-length movie on a single CD - compress a 4.7 GB DVD- movie to 650 MB.
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9 Digital television Digital television systems are of two types. In the system of the first type (fully digital) conversion of the transmitted image into a digital signal and reconverting the digital signal into an image made directly to the light signal converters (camcorders) and signal-to- Light (TV screens). At all levels of the transmission path of image and sound information is transmitted in digital form. Such systems developed so far only.
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10 Digital television In digital television systems of the second type of the analog signal received from the sensors (cameras), converted to digital form, transmitted, and then again at the receiver acquires the analog form, which is fed to a video monitor. Leveraging existing sensors analog TV signals and signal-to-light converters in television receivers.
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11 Digital television Now there are three digital TV standard: - ATSC (Advanced Television Systems Committee) - American; - ISDB (Integrated Services Digital Broadcasting) - Japanese (planned to use this standard in Brazil); - DVB (Digital Video Broadcasting) - European.
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12 Digital television Based on the methods of delivery to the consumer signal, digital TV is divided into four types: satellite, terrestrial, cable and the Internet ( for IP networks ). They are, to some extent, common in many countries, and each species has its own advantages and disadvantages. Satellite TV has extensive coverage, the availability of the most remote corners and greater bandwidth (one satellite can serve multiple broadcast channels and, in addition to this, more and perform other useful functions ). Of the disadvantages can be called high cost of implementation.
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13 Digital television Broadcasting requires less equipment. The signal is transmitted to the surrounding area special relay stations (towers ). The original signal are obtained from the same satellites. The disadvantage of broadcasting signal is low immunity. Besides, most of the equipment intended for rebroadcast of analog broadcasting and is not able to transmit a digital signal. Cable TV provides high quality signal transmission, undemanding to format ( it depends on the type of transmission equipment, not on the cable itself ), but also expensive. TV via the Internet ( for IP- networks ) appeared not so long (in comparison to other formats ). It is designed from the outset for digital broadcasting, but the high hardware requirements and network bandwidth is not yet allow you to work with the broadcast are of high quality.
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14 Digital television In the European standard these types considered, therefore allocated terrestrial DVB-T (Terrestrial), satellite DVB-S (Satellite) and cable DVB-C (Cable) broadcasting and broadcasting for portable DVB-H (Handheld). American and Japanese ISDB ATSC standards - especially land and not subdivided into species.
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15 Digital television Broadcast digital signal requires some training. Firstly, this standardization principles broadcasting. Second, the installation of new equipment, which will transmit a digital signal on the air. And thirdly, the need to convince the population to replace conventional television sets with new ones capable of receiving a digital signal, or, in extreme cases, to purchase special equipment to receive and decode the signal. It costs money, and not all consumers are willing to pay them. But there are benefits that are uniquely able to " tip the scales " in favor of digital television. This is - the higher quality audio and video, broadcast and high noise immunity, finally able to make television interactive. " Digital " program will allow beholder to vote, to choose the best moments to record your transfer and, moreover, to see only those transmissions that you want.
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