01-04-2020-Oxford_English_for_Infomation_Technology (1171844), страница 10
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More than one match is possible.Column AColumn BMIDIwatching moviesMP3composing music on a PCDVDdownloading music from the InternetMPEGusing reference works like encyclopaediasStudy this diagram which explains MP3. Answer these questions:123How does MP3 reduce the size of music files?What can you obtain from www. mp3. com?How can you listen to MP3 files?Original FileFig 1How MP3 will transform musicRfter MP3Match these captions to the pictures in Fig 1.
Consider againyour answers to Task 2.aOnce you've paid by credit card (unless it's one of the millions offree files), music is downloaded to your PC.b The original music file is stripped of anything that is inaudible tothe human ear. After MP3 has done its work, the file is reducedto roughly one twelfth that of the original recording.c MP3 files can be listened to on your PC, a dedicated MP3 player,or your hi-fi.d MP3 files are put on a website, where browsers can listen tosamples and buy a single track or album...
or even create theirown compilation.Read this text to find the answers to these questions.READING1234What does MP3 stand for?What is the difference between MP3 and WAV files?What kind of sound does MP3 strip out?What kind of information is included in the tag?Understanding MP3The name comes from MPEG(pronounced EM-peg), whichstands for the Motion PictureExperts Group.
MPEGdevelops standards for audioand video compression. MP3is actually MPEG AudioLayer 3.MP3 competes with anotheraudio file format called WAV.The key difference is thatMP3 files are much smallerthan WAV files. An MP3 filecan store a minute of soundper megabyte, while a WAVfile needs 11 or 12 megabytesto hold the same amount.How does MP3 achieve thiscompression? CDs and audiofiles don't reproduce everysound of a performance.Instead, they sample theperformance and store adiscrete code for eachsampled note.
A CD or WAVfile may sample a song 44, 000times a second, creating ahuge mass of information.By stripping out sounds mostpeople can't hear, MP3significantly reduces theinformation stored. Forinstance, most people can'thear notes above a frequencyof 16kHz, so it eliminatesthem from the mix. Similarly,it eliminates quiet soundsmasked by noise at the samefrequency. The result is a filethat sounds very similar to aCD, but which is muchsmaller. An MP3 file cancontain spoken wordperformances, such as radioshows or audio books, as wellas music. It can provideinformation about itself in acoded block called a tag. Thetag may include theperformer's name, a graphicsuch as an album cover, thesong's lyrics, the musicalgenre, and a URL for moredetails.62UNIT 9 MultimediaRead the rest of this text to find the answers to thesequestions:12345678How do you play MP3 files?What does the Windows Media Player file do with an MP3 file?What is a standalone player?What special features can players offer?What information can you obtain by clicking on the track infobutton?What does a skin enable you to do?How do you play music from a CD-ROM on an MP3 player?What hardware and software do you need to make your ownaudio CDs?Other MP3 features include:Players.Most standalone players havemany features beyondWindows' default MediaPlayer.
To control what musicyou play, players let yougroup songs into playlists andrandomize the selections. Tocontrol how the musicsounds, they offer spectrumanalyzers, graphic equalizers,and frequency displays.Track info.A track info button gives youthe information on the MP3file's tag. Other buttons maytake you to a music librarywhere you can organize yourMP3 files by performer orgenre.Skins or themes.These programs are designedto change the appearance ofthe most popular players.They're akin to the wallpaperthat alters the look of theWindows desktop.
With askin, a player can become ajukebox, a car dashboard, or aStar Trek tricorder. Think ofthem as easilyinterchangeable faceplates.Rippers and encoders.A ripper is a program thatrips songs from a CD in yourCD-ROM drive and turnsthem into WAV files. Anencoder converts WAV filesinto MP3 files or vice versa.Many MP3 playersincorporate rippers andencoders and can do bothsteps in one.Recorders.With a writeable CD-ROMdrive, a recorder program letsyou create your own audioCDs.UNIT 9 MultimediaLANGUAGE WORK-ing clauses (2) cause and effectStudy this sentence.1 Using MIDI, computers can communicatewith synthesisers.clause explanation can be placed before, orafter the main clause as in example 2.2It contains two clauses.
An -ing clause:DVD drives read DVD disks (by) using bluelaser light.We can also use -ing clauses to link a causeand effect.Using MIDIand a main clause:computers can communicate withsynthesisers3 A WAV file may sample a song 44, 000 timesa second, [cause] creating a huge mass ofinformation. [effect]We can use an -ing clause, as in example 1, toexplain how something happens. The -ingMatch each cause and effect.
Then link them with an -ingclause.CauseEffect1Computers with MIDI interface boardscan be connected to MIDI instruments.a2Each side of a DVD can have two layers.This permits extra information to bestored on the performer and othertrack details.3MP3 removes sounds we can't hear.bYou can create your own compilation.4You can download single tracks.cThis allows you to sample a new groupbefore buying their CD.dThis gives an enormous storagecapacity.eThis allows the music being played tobe stored by the computer anddisplayed on the monitor.fThis enables you to change theappearance of your player.gThese allow you to control the way themusic sounds.hThis produces much smaller files.5 Each MP3 file has a tag.6MP3 players contain several devices.7You can download a skin program.8You can legally download some music.6364UNIT 9 MultimediaExplain how each of these actions happen. The explanationsare available in Tasks 2, 3 and 4.1 MP3 reduces the information stored.2 You can alter the look of your MP3 player.3 You can 'rip' the audio information from a CD.4 You can convert a WAV file to MP3 format.5 You can view the lyrics, notes and author data.6 You can control how the music sounds.7 You can access many free and legal music files for downloading.8 You can play MP3 files through your sound system.SPEAKINGWork in pairs, A and B.
With the help of the notes provided,explain to your partner one aspect of multimedia.Student A Your notes are on page 185.Student B Your notes are on page 191.Link your notes into a text describing one aspect of multimedia.Choose either the Student A or the Student B notes.WRITINGStudy the diagram, Fig 2, which illustrates how MIDI operates.Then link each set of sentences into one complex sentence to form acontinuous paragraph. You may add, omit and change words.1 Most modern music is mixed.This uses computers.2 Musicians record their music into a computer system.This system is called a Musical Instrument Digital Interface(MIDI).3 MIDI was developed as a standard interface.MIDI is for linking music synthesisers and instruments together.4 Computers can be connected to MIDI instruments.These computers are fitted with MIDI interface boards.This allows the music to be stored on computer.This allows the music to be displayed on the monitor.The music is being played.5 The music can be displayed as a musical score.The music can be edited.This uses all the features of a mixing desk.UNIT 9 Multimedia65The PC SetupWhat goes where in a typical PC music set-upSoundcardModemTo connect to the net forall that free software you'redreaming about.
Connectsto the COM port.Put into a free slot at theback of the PC and providesthe interface to the keyboard.MIDI keyboardSpeakersConnects to the speakerout on your soundcard.For playing the sounds onthe card or triggering itsown sounds if it has them(i.
e. a MIDI synth).Fig 2What is MIDI?6 The music can also be printed out from the computer.The music is being played.7 MIDI doesn't transmit any sound.It transmits simple binary information.8 The information is called a MIDI message.The message encodes sound as 8-bit bytes of digitalinformation.9 The most common messages consist of instructions.These instructions tell the receiving instrument to play a note fora specific duration of time.10 The instructions also contain details of how loud to play thatnote.The instructions contain a number.The number indicates which instrument to play.Number 67 is a saxophone.66 UNIT 9 MultimediaSPECIALIST READINGB12345678Find the answers to these questions in thefollowing text.Into what two components is the data streamsplit?What information does an Intra framecontain?What is stored in the P-frames following an Iframe?What is stored in a P-frame in the case of abouncing ball?What gives the massive reduction in theamount of information needed to reproducea video sequence?Why is a new l-frame used after a few Pframes?What is stored in a B-frame?Why do B-frames not propagate errors?Predicted framesBidirectional framesIntra framesThe key to MPEG'scompression success isbasing some frames oninformation stored inothers, and describingjust the changes.UNIT 9 Multimedia 67The most common system for the compression ofvideo is MPEG.
It works like this. The single datastream off the CD-ROM is split into video andaudio components, which are then decompressedusing separate algorithms. The video is processedto produce individual frames as follows. Imaginea sequence of frames depicting a bouncing ball ona plain background. The very first is called anIntra Frame (I-frame). I-frames are compressedusing only information in the picture itself justlike conventional bitmap compression techniqueslike JPEG.Following I-frames will be one or more predictedframes (P-frames).
The difference between the Pframe and the I-frame it is based on is the onlydata that is stored for this P-frame. For example,in the case of a bouncing ball, the P picture isstored simply as a description of how the positionof the ball has changed from the previous I-frame.This takes up a fraction of the space that would beused if you stored the P-frame as a picture in itsown right.
Shape or colour changes are also storedin the P-frame. The next P-frame may also bebased on this P-frame and so on. Storingdifferences between the frames gives the massivereduction in the amount of information needed toreproduce the sequence. Only a few P-frames areallowed before a new I-frame is introduced intothe sequence as a new reference point, since asmall margin of error creeps in with each P-frame.Between I and P-frames are bi-directional frames(B-frames), based on the nearest I or P-framesboth before and after them.
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