计算机专业英语Unit-8-Multimedia课件

计算机专业英语Unit8Multimedia计算机专业英语Unit8Multimedia1BackgroundKnowledge背景知识多媒体技术是指一种对文本、声音、图形、图像、动画、视频等多媒体信息进行采集、存储、加工或集成的计算机技术。多媒体技术已经深入到我们生活、工作和学习的各个方面，例如可视电话、视频会议、远程医疗、电子出版等等。声音是一种重要的信息载体，如何让计算机能够处理声音是多媒体技术中重要的一部分。BackgroundKnowledge背景知识多媒体技术NewWordsandUsefulExpressionsvibrate/vaɪ'breɪt/振动,激动,颤动;使颤动,使摆动,使振动sensitive/'sensɪtɪv/敏感的;神经过敏的;易受伤害的;易怒的sensation/sen'seɪʃn/感觉,知觉;轰动,激动;感觉能力,知觉作用;pitch/pɪtʃ/音高,声音相对的高低graphically/ˈgræfɪkli/通过图表;轮廓分明地;生动地waveform/'weɪvfɔ:m/波形diagram/ˈdaɪəgræm/图表plot/plɔt/划分,绘图axis/ˈæksɪs/轴NewWordsandUsefulExpressioNewWordsandUsefulExpressionstuning/tuːn/调音,调律fork/fɔːk/叉peak/pɪːk/山顶,山峰;高峰,最高点,顶端;trough/trɔf/槽volt/vəʊlt/伏特digitiz(s)ation/dɪdʒaɪtaɪ'zeɪʃən/数字化reconstruct/ˌriːkənˈstrʌkt/重建,再建modulation/ˈmɔdjʊleɪʃn/调制uncompressed未经压缩的,没有压缩的NewWordsandUsefulExpressioNewWordsandUsefulExpressionsquantization/‚kwɑntə'zeɪʃn/量化analogue/ˈænəlɔg/相似物;类似物;类似情况normaliz(s)ation/ˌnɔ:məlaɪ'seɪʃn/正常化;

标准化;

正态化maximiz(s)e/'mæksɪmaɪz/最大化harmonic/hɑː'mɔnɪk/谐波;谐函数;和声high(low)-pitched声调高(低)的

vertical(y)axis垂直(y)轴horizontal(x)axis水平(X)轴NewWordsandUsefulExpressioNewWordsandUsefulExpressionstuningfork音叉samplerate采样率，样本率，采样速度PulseCodeModulation(PCM)称脉冲编码调制quantizationerror量化误差analoguesignal模拟信号roundingerrors舍入误差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计算机专业英语Unit8Multimedia计算机专业英语Unit8Multimedia17BackgroundKnowledge背景知识多媒体技术是指一种对文本、声音、图形、图像、动画、视频等多媒体信息进行采集、存储、加工或集成的计算机技术。多媒体技术已经深入到我们生活、工作和学习的各个方面，例如可视电话、视频会议、远程医疗、电子出版等等。声音是一种重要的信息载体，如何让计算机能够处理声音是多媒体技术中重要的一部分。BackgroundKnowledge背景知识多媒体技术NewWordsandUsefulExpressionsvibrate/vaɪ'breɪt/振动,激动,颤动;使颤动,使摆动,使振动sensitive/'sensɪtɪv/敏感的;神经过敏的;易受伤害的;易怒的sensation/sen'seɪʃn/感觉,知觉;轰动,激动;感觉能力,知觉作用;pitch/pɪtʃ/音高,声音相对的高低graphically/ˈgræfɪkli/通过图表;轮廓分明地;生动地waveform/'weɪvfɔ:m/波形diagram/ˈdaɪəgræm/图表plot/plɔt/划分,绘图axis/ˈæksɪs/轴NewWordsandUsefulExpressioNewWordsandUsefulExpressionstuning/tuːn/调音,调律fork/fɔːk/叉peak/pɪːk/山顶,山峰;高峰,最高点,顶端;trough/trɔf/槽volt/vəʊlt/伏特digitiz(s)ation/dɪdʒaɪtaɪ'zeɪʃən/数字化reconstruct/ˌriːkənˈstrʌkt/重建,再建modulation/ˈmɔdjʊleɪʃn/调制uncompressed未经压缩的,没有压缩的NewWordsandUsefulExpressioNewWordsandUsefulExpressionsquantization/‚kwɑntə'zeɪʃn/量化analogue/ˈænəlɔg/相似物;类似物;类似情况normaliz(s)ation/ˌnɔ:məlaɪ'seɪʃn/正常化;

标准化;

正态化maximiz(s)e/'mæksɪmaɪz/最大化harmonic/hɑː'mɔnɪk/谐波;谐函数;和声high(low)-pitched声调高(低)的

vertical(y)axis垂直(y)轴horizontal(x)axis水平(X)轴NewWordsandUsefulExpressioNewWordsandUsefulExpressionstuningfork音叉samplerate采样率，样本率，采样速度PulseCodeModulation(PCM)称脉冲编码调制quantizationerror量化误差analoguesignal模拟信号roundingerrors舍入误差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