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Chapter12

Sep 05, 2014

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Technology

 

  • Chapter12 VideoFormats andSoftwareOBJECTIVESAt the end of this chapter, you should be able to:1. state four main types of video formats and standards;2. identify several examples of codec formats and video file formats thatINTRODUCTIONthe market; andare currently available in3. learn several basic techniques of processing video using the AdobePremier software. INTRODUCTIONIn the previous chapters, you learned about video components in multimedia. Inthis chapter we will focus on some of the video formats and standard that areregularly used. You would also be given explanations, regarding the types ofcodec formats and video file formats that are currently available in the market. Atthe end of this chapter, you will also learn about several basic techniques forprocessing video with the use of the Adobe Premier software, which is the videoapplication software used extensively today.12.1 VIDEO FORMATS AND STANDARDSAs what we have learnt, video broadcasts are based on frame rate per second orfps. Do you know that video is played on different frame rate per seconddepending on the country? For example, in the United States, video is played at a

CHAPTER 12 VIDEO FORMATS AND SOFTWARE213rate of 30 frames per second. This is based on the guideline or standard,prescribed by the committee of the country, which is the National TelevisionStandards Committee (NTSC), while countries like United Kingdom, Australiaand most countries in Asia, use the PAL broadcasting system or PhaseAlternation Line. Unlike the NTSC system, the PAL system uses 25 frames persecond for videos and television playback. Hence, majority of the television setsand video recorders have multiple systems capability (multi system ready). Thisgives the audience the opportunity to enjoy the benefits of both the systems.The four main formats and standards for broadcasting and video are, NTSC,PAL, SECAM and HDTV. These standards may be converted or interpretedamong each other but usually, the conversion process causes the quality to drop,and there are some processes that require specific hardware. Therefore, it isimportant to understand each of these standards, and identify where yourmultimedia project will be played, or presented.The following are brief discussions on the video formats and standards that areavailable currently;(a) NTSCNTSC or National Television Standards Committee is a standard based onspecifications fixed by the National Television Standards Committee, 1952.It is used in the United States of America and Japan. These standards definea method for encoding information into the electric signal that ultimatelycreates a television picture. According to NTSC standards, a video frameconsists of 525 horizontal scan lines that is produced every 1/30 of a second.NTSC is also known as, Never Twice the Same Colour.(b) PALPAL or Phase Alternate Line is a standard that is used in Britain, Europeancountries and most of the countries in Asia. According to Vaughan (2001),PAL is an integration method that adds colours to black and whitetelevision signals. It produces 625 lines at a frame rate of 25 frames rate persecond (fps); each line requires a time of 1/50 per second to be produced (50Hz).(c) SECAMSECAM or Sequentiel Couleur avec memoire is a standard that is used inFrance, Russia and a few other countries. Although it is almost the same asPAL and NTSC, the broadcasting technology and method of SECAM 214UNIT 3 MULTIMEDIA COMPONENTS II: AUDIO & VIDEO distinguishes it from the other standards. To tackle this problem, the majority of television sets sold in European nations have components that can accept both the PAL and SECAM systems.(d)HDTV HDTV or High Definition TV is a new standard of television technology. HDTV provides clear and quality sounds and pictures just like 35mm movies. The main difference between the old television standard and HDTV is its high resolution. HDTV consists of 1080 active lines compared to the current television pictures standard of only 486 active lines.REFERENCESTo obtain more information regarding video formats and standards, refer toChapter 12 of the book, Multimedia: Making It Work, 5th Edition, by TayVaughan, 2001.Advanced Television Systems Committee is an InternationalOrganisation involved in the development of standards for digitaltelevision. Visit its website at http://www.atsc.org.12.2 CODEC FORMATSCodec format is defined as an algorithm to compress and decompress. It is amechanism that is used to compress digital video. In the previous chapters, youlearnt about the methods and techniques of compression. In this chapter, we willview several digital video formats that are currently available in the market.Among them are CinePak and Indeo, which can be used in various platformssuch as Macintosh, Windows or Unix. Examples of other codecs are JPEG, MPEGand Sorenson. You can choose any of the codecs that are available in the marketto produce videos. (See the table quoted from the multimedia book, MultimediaLiteracy, by Fred T. Hofstetter, on the following page). CHAPTER 12 VIDEO FORMATS AND SOFTWARE 21512.2.1 CinePakCinePak format was formerly known as, Compact Video. It is the most popularcodec for the Quick Time file. CinePak is a lossy compression format. If you usethe CinePak format, you must ensure that the original video source that has yet tobe compressed is of high quality.CinePak can support frame differencing. It is asymmetrical whereby it requires alonger time for compression. For example, a video that is only 15 seconds willtake up to an hour to be compressed. However, the video produced is smoothand its file size is satisfactory.12.2.2 Indeo/DVIBesides CinePak, Indeo (also known as DVI) is a codec format developed by Intel.Generally, Indeo can be in lossy or lossless compression forms and can supportframe differencing. However, it is less asymmetrical compared to CinePak.Indeo requires more processing time for decompression. This causes the videoproduced to be less smooth compared to CinePak. Indeo is a special codec formatfor the VfW (Video for Windows) file, but Quick Time 2.0 can also support thisformat. Therefore, it has become the second most popular codec format for digitalvideo.12.2.3 JPEGWhen you view a JPEG format, you may think that it is one of the file formats forgraphics or images! In fact, it is the same as the JPEG graphics format. Sometimesit is dubbed as JPEG motion. You must remember that video comprises of a set offrames, where each image in a frame can be compressed using JPEG compression.JPEG assumes that each of these video frames as static images. This produces arather large file size and a sizeable drop in terms of quality with a correspondinglarge compression ratio.Compression using JPEG entails specific hardware, but the process ofdecompression can be implemented without hardware, but with softwaresupport particularly QuickTime for Apple and Video for Windows.Choosing suitable codec is not an easy task. Read the quotation below regardingthe Comparison of Codec Formats, to help you make the right decision. 216 UNIT 3 MULTIMEDIA COMPONENTS II: AUDIO & VIDEOFigure 12.1: different codecformat CHAPTER 12 VIDEO FORMATS AND SOFTWARE217 To obtain more information regarding video codec, visit its website at http://www.icanstream.tv/CodecCentral/index.html.Exercise 12.1 Give ONE difference between Indeo and CinePak.12.3 VIDEO FILE FORMATSAfter the video has been digitised and converted into a digital video file, youshould choose a video file format to store the video clip. For use on the computer,the main choice is the Microsofts Video for Windows (.AVI), QuickTime andsome versions of MPEG. Although there are many file formats such as theAutoDesks FLC, most of the digital video files comprise of formats from MPEG,AVI or QuickTime. Figure 12.2: Main digital video file formats 218UNIT 3 MULTIMEDIA COMPONENTS II: AUDIO & VIDEO12.3.1 QuickTimeQuickTime is among the best video file formats and it is developed by AppleComputer. Both the Macintoshs system and Windows support this file formatextensively. Most of the Windowss 95/98 systems can play the QuickTime video,but it may require a device installation software if the version of QuickTimeneeded to play the video is later than the version supported by the computersystem.Although, you may be forced to equip your computer with the requiredQuickTime installation software, QuickTime is still the main choice for crossplatform multimedia development.QuickTime does not require a high cost as the files required to replay video clipsin QuickTime format are circulated free of charge by Apple computer.12.3.2 Microsofts Video for Windows (.AVI)Microsoft first introduced Video for Windows in 1992. Its aim was to prepare astandard for video under the Windows operating system. Although the AVIformat is not the best format in the market, however, it is the most widely used.This is because most of the personal computer owners in the world use theWindows operating system. Therefore, you do not require any additionalsoftware to play AVI files in the Windows system environment. For systems thatare not in the Windows environment such as the Macintosh computer that doesnot support the AVI format, you need special software that can be obtained fromMicrosoft to view the video clips.The Microsofts Video for Windows program is based upon the .AVI (AudioVideo Interleave) file format where the audio and video is "interleaved." Thisenables audio and video to be played simultaneously.12.3.3 MPEGMPEG (Motion Picture Expert Group) is gaining popularity in tandem with theincrease in computer systems. MPEG-1 encodes video-clips on 352 x 240, 320 x240, 176 x 112 or 160 X 112 screen sizes only, but it can be played on full screen at30 fps with neat frame rate and satisfactory image quality.There are many MPEG versions in the market such as MPEG 1, MPEG-2 andMPEG-4. MPEG-1 is the original format designed for quality VHS pictures atCD-ROM data rat