計(jì)算機(jī)專業(yè)英語Unit-8-Multimedia課件

計(jì)算機(jī)專業(yè)英語Unit8Multimedia計(jì)算機(jī)專業(yè)英語Unit8Multimedia1BackgroundKnowledge背景知識多媒體技術(shù)是指一種對文本、聲音、圖形、圖像、動畫、視頻等多媒體信息進(jìn)行采集、存儲、加工或集成的計(jì)算機(jī)技術(shù)。多媒體技術(shù)已經(jīng)深入到我們生活、工作和學(xué)習(xí)的各個方面，例如可視電話、視頻會議、遠(yuǎn)程醫(yī)療、電子出版等等。聲音是一種重要的信息載體，如何讓計(jì)算機(jī)能夠處理聲音是多媒體技術(shù)中重要的一部分。BackgroundKnowledge背景知識多媒體技術(shù)NewWordsandUsefulExpressionsvibrate/va?'bre?t/振動,激動,顫動;使顫動,使擺動,使振動sensitive/'sens?t?v/敏感的;神經(jīng)過敏的;易受傷害的;易怒的sensation/sen'se??n/感覺,知覺;轟動,激動;感覺能力,知覺作用;pitch/p?t?/音高,聲音相對的高低graphically/?gr?f?kli/通過圖表;輪廓分明地;生動地waveform/'we?vf?:m/波形diagram/?da??gr?m/圖表plot/pl?t/劃分,繪圖axis/??ks?s/軸NewWordsandUsefulExpressioNewWordsandUsefulExpressionstuning/tu?n/調(diào)音,調(diào)律fork/f??k/叉peak/p??k/山頂,山峰;高峰,最高點(diǎn),頂端;trough/tr?f/槽volt/v??lt/伏特digitiz(s)ation/d?d?a?ta?'ze???n/數(shù)字化reconstruct/?ri?k?n?str?kt/重建,再建modulation/?m?dj?le??n/調(diào)制uncompressed未經(jīng)壓縮的,沒有壓縮的NewWordsandUsefulExpressioNewWordsandUsefulExpressionsquantization/?kwɑnt?'ze??n/量化analogue/??n?l?g/相似物;類似物;類似情況normaliz(s)ation/?n?:m?la?'se??n/正常化;

標(biāo)準(zhǔn)化;

正態(tài)化maximiz(s)e/'m?ks?ma?z/最大化harmonic/hɑ?'m?n?k/諧波;諧函數(shù);和聲high(low)-pitched聲調(diào)高(低)的

vertical(y)axis垂直(y)軸horizontal(x)axis水平(X)軸NewWordsandUsefulExpressioNewWordsandUsefulExpressionstuningfork音叉samplerate采樣率，樣本率，采樣速度PulseCodeModulation(PCM)稱脈沖編碼調(diào)制quantizationerror量化誤差analoguesignal模擬信號roundingerrors舍入誤差garbagenoise噪音doublebass低音提琴jazzdrumming爵士鼓NewWordsandUsefulExpressioSoundConceptSomethingvibrates,itmakestheairvibrate,theairvibratesthesensitivebonesinyourear,andthissensationisregisteredinyourbrainassound.SoundConceptSomethingvibrateSoundRepresentationDiagramThe'size'ofthevibrationsisplottedonthevertical(y)axisandthetimeitwasmeasuredatisplottedonthehorizontal(x)axis.SoundRepresentationDiagramThDigitizationThewayanaturalthingsuchassoundisdigitizedisreplicatingthewaytheearworks.Insteadofsensitivebones,youhavesensitivematerialthatwillvibratejustlikethebonesinyoureardo.Thesevibrationsthencauseanelectricalcurrenttobecreated.Thistranslatestheamplitudeofasoundtoanelectricalvoltagedifference.DigitizationThewayanaturalDigitizationDiagramEssentiallywhatyouwillgetistheexactsamediagramasabovebutinsteadtheyaxiswillbevolts.Thiscanthenbemeasuredandconvertedintobinarythatcomputerscanuse.DigitizationDiagramEssentiallAudioPropertiesaudiohastwoproperties:bitsandsamplerate.Bits(orBinarydigITS)istheamountofdifferentvoltages(amplitudes)thatcanbesampled.So,justas8bitvideoonlyhas256colors,8bitaudioonlyhas256differentamplitudesitcansample.SampleRateistheamountoftimeseverysecondthattheaudioissampledorgivenabinarynumber.CDsaresampledat44.1KHzor44,100timesasecond.16bit44.1KHzaudiomeans-65,536possiblelevelsmeasured44,100timesasecond.AudioPropertiesaudiohastwoPCMThissystemofdigitizingaudioisknownasPulseCodeModulation(PCM).Themostcommonoftheseis16bit44.1KHzaudioasfoundonCDs.PCMThissystemofdigitizingaSampleRateandRecreationComparisonSampleRateandRecreationComGarbageNoise&NormalizationThepeaksandtroughsoftheincomingsoundbeyondtherangeofthesamplingsystemtothetopsandbottomsofthepeaksare'clipped'whichcausesthegarbagenoise.Ifyouwanttoincreasethevolume(gain)withoutcreatinggarbagedata,thisprocessiscalledNormalization.GarbageNoise&NormalizationNormalizationProcess1)Findsthehighestamplitudeofanywaveintheaudio2)Amplifiestheentireaudiowavesothatthisamplitudedoesnotexceedthemaximumthatcanbestoredinbinary-i.e.withoutclipping.Essentiallytheprincipleistofindthemaximumgainwithoutclippinganyofyourpeaks.--BestEffort,sometimesclippingisunavoidable.NormalizationProcess1)FindsComplexityofSoundNotonlyistheremorethanonesoundbutthissoundisalsomadeupofharmonicsandotheraudiowondersthatmaketheinstrumentsandvoicessoundthewaytheydo.Thereareafewrecognizablepatternsbutbecausethewaveformsarecombined,itisdifficulttoseparatesoundsofdifferentinstrumentsinonewaveform.ComplexityofSoundNotonlyis計(jì)算機(jī)專業(yè)英語Unit8Multimedia計(jì)算機(jī)專業(yè)英語Unit8Multimedia17BackgroundKnowledge背景知識多媒體技術(shù)是指一種對文本、聲音、圖形、圖像、動畫、視頻等多媒體信息進(jìn)行采集、存儲、加工或集成的計(jì)算機(jī)技術(shù)。多媒體技術(shù)已經(jīng)深入到我們生活、工作和學(xué)習(xí)的各個方面，例如可視電話、視頻會議、遠(yuǎn)程醫(yī)療、電子出版等等。聲音是一種重要的信息載體，如何讓計(jì)算機(jī)能夠處理聲音是多媒體技術(shù)中重要的一部分。BackgroundKnowledge背景知識多媒體技術(shù)NewWordsandUsefulExpressionsvibrate/va?'bre?t/振動,激動,顫動;使顫動,使擺動,使振動sensitive/'sens?t?v/敏感的;神經(jīng)過敏的;易受傷害的;易怒的sensation/sen'se??n/感覺,知覺;轟動,激動;感覺能力,知覺作用;pitch/p?t?/音高,聲音相對的高低graphically/?gr?f?kli/通過圖表;輪廓分明地;生動地waveform/'we?vf?:m/波形diagram/?da??gr?m/圖表plot/pl?t/劃分,繪圖axis/??ks?s/軸NewWordsandUsefulExpressioNewWordsandUsefulExpressionstuning/tu?n/調(diào)音,調(diào)律fork/f??k/叉peak/p??k/山頂,山峰;高峰,最高點(diǎn),頂端;trough/tr?f/槽volt/v??lt/伏特digitiz(s)ation/d?d?a?ta?'ze???n/數(shù)字化reconstruct/?ri?k?n?str?kt/重建,再建modulation/?m?dj?le??n/調(diào)制uncompressed未經(jīng)壓縮的,沒有壓縮的NewWordsandUsefulExpressioNewWordsandUsefulExpressionsquantization/?kwɑnt?'ze??n/量化analogue/??n?l?g/相似物;類似物;類似情況normaliz(s)ation/?n?:m?la?'se??n/正?；?

標(biāo)準(zhǔn)化;

正態(tài)化maximiz(s)e/'m?ks?ma?z/最大化harmonic/hɑ?'m?n?k/諧波;諧函數(shù);和聲high(low)-pitched聲調(diào)高(低)的

vertical(y)axis垂直(y)軸horizontal(x)axis水平(X)軸NewWordsandUsefulExpressioNewWordsandUsefulExpressionstuningfork音叉samplerate采樣率，樣本率，采樣速度PulseCodeModulation(PCM)稱脈沖編碼調(diào)制quantizationerror量化誤差analoguesignal模擬信號roundingerrors舍入誤差garbagenoise噪音doublebass低音提琴jazzdrumming爵士鼓NewWordsandUsefulExpressioSoundConceptSomethingvibrates,itmakestheairvibrate,theairvibratesthesensitivebonesinyourear,andthissensationisregisteredinyourbrainassound.SoundConceptSomethingvibrateSoundRepresentationDiagramThe'size'ofthevibrationsisplottedonthevertical(y)axisandthetimeitwasmeasuredatisplottedonthehorizontal(x)axis.SoundRepresentationDiagramThDigitizationThewayanaturalthingsuchassoundisdigitizedisreplicatingthewaytheearworks.Insteadofsensitivebones,youhavesensitivematerialthatwillvibratejustlikethebonesinyoureardo.Thesevibrationsthencauseanelectricalcurrenttobecreated.Thistranslatestheamplitudeofasoundtoanelectricalvoltagedifference.DigitizationThewayanaturalDigitizationDiagramEssentiallywhatyouwillgetistheexactsamediagramasabovebutinsteadtheyaxiswillbevolts.Thiscanthenbemeasuredandconvertedintobinarythatcomputerscanuse.DigitizationDiagramEssentiallAudioPropertiesaudiohastwoproperties:bitsandsamplerate.Bits(orBinarydigITS)istheamountofdifferentvoltages(amplitudes)thatcanbesampled.So,justas8bitvideoonlyhas256colors,8bitaudioonlyhas256differentamplitudesitcansample.SampleRateistheamountoftimeseverysecondthattheaudioissampledorgivenabinarynumber.CDsaresampledat44.1KHzor44,100timesasecond.16bit44.1KHzaudiomeans-65,536possiblelevelsmeasured44,100timesasecond.AudioPropertiesaudiohastwoPCMThissystemofdigitizingaudioisknownasPulseCodeModulation(PCM).Themostcommonoftheseis16bit44.1KHzaudioasfoundonCDs.PCMThissystemofdigitizingaSampleRateandRecreationComparisonSampleRateandRecreationComGarbageNoise&NormalizationThepeaksandtroughsoftheincomingsoundbeyondtherangeofthesamplingsystemtothetopsandbottomsofthepeaksare'clipped'whichcausesthegarbagenoise.Ifyouwantt