17.SignalReadercomponent

SignalReadercomponentallowsreadingdata fromasignalsourcefile,andplayingitbackwith selectedrate.SignalReaderoutputdata streamformatissimilartoSignalGenerator,seechapter16.10.

SignalReadercomponentcurrentlysupportsacoupleofformats,wavandsid.

17.1Keyproperties

FileNamedefinesthefile toopened,like“c:\\wavedata\\audioclip1.wav”Factorsetstheoutputfactor.Rawsignalsamplesaremultipliedwith thisvalue.OutputIntervalis similartoSignalGenerator’sproperty,seesection16.1.

IsLoopingallowsfilereadtojumptothebeginningofthe file,whentheendoffilehasbeenreached.

Afterthefile hasbeenopened,thefollowingpropertiescanbeusedtogetinformationofthefile:

ChannelCount:thechannelcountofthe file.SamplingFrequency:samplingfrequencyin Hz.FileSize:Filesizeinbytes.

Length:Samplecountforeachchannel.Itmaynotbeexactforall signalfileformats.

IsReaderEnabled:Statustellingisthe componentstartedandreadingdata. IfLoopingissettofalseandendoffileis reached,IsReaderEnabledwillchangetofalse.

17.2Openingfilequicklyforplayback

CallOpenFile(…)methodsuppliedwithafilename.Filenamemusthaveanextensionofsupportedformats.Then, callStart()method

signalReader.OpenFile(“c:\\wavedata\\audioclip1.wav”);

signalReader.Start();

It willstartplaybackofaPCM-formattedWAV file.

PlaybackcanbestoppedbycallingStopRequest()method.

Figure17-1.SignalReaderreadsawavfileandLightningChartSampleDataSeriesdrawthesignal.AcursorlineisusedtomarkcurrentreadingpositionandX-axisscrollposition.

AudioInputcomponentallowsuserto capturesignalfromWindows’recordingdevicetoSystem.Doublevalues.ThesevaluescanthenberenderedonLightningChartUltimate,sendtoan AudioOutputcomponent,savedtoafileetc…

18.1Properties

BitsPerSample–Getsorsetshowmanybitsareallocatedper sample.Supportedvaluesare8and16.If othervalueisused,16isusedinstead.IssettablewhenIsInputEnabledis false.

IsInputEnabled–Getsorsetsthestateofthisinstance(i.e. startsorstopsit).Settingthispropertytrueis thesameascallingStartmethodwherefalseisthesameascallingStopmethod.

IsStereo–Getsorsetswhethertousetwochannels(stereo)orjustone(mono).Issettablewhen

IsInputEnabledis false.

LicenseKey–Getsorsetslicensekeyin normalorencryptedformat.

RecordingDevice–Getsorsetsthe currentrecordingdevice.Is settablewhenIsInputEnabledis false.Bysettingthispropertynull,Windows'defaultrecordingdeviceisused.

SamplesPerSecond–Getsorsetssamplingfrequency.Is settablewhenIsInputEnabledisfalse.

ThreadInvoking–Getsorsetswhetherthisinstanceautomaticallysynchronizesitseventstothemain

UI threadhenceeliminatingtheneedtocall Control.Invokemethodoncaller'sside.

Volume–Getsorsetsvolume(0-100).IssettablewhenIsInputEnabledis false.

18.2Methods

GetRecordingDevices–Usethisstaticmethodtogeta listofavailableWindowsrecordingdevices.

RequestStop–SignalsthisAudioInputinstancetostop.Stopdoesnotoccurimmediatelyafterexitingthismethod.BysubscribingtoStoppedevent,callerisnotifiedwheneverythinghas stopped.

Start–Startsreadingaudiofromselectedrecordingdevice.Startedeventistriggeredwheninternalthreadisabouttostart.

DataGenerated–Occurswhenanewsetofaudiodatahas beengenerated.Dataanditsfirstsample’s

timestampcanbereadfromaDataGeneratedEventArgsobjectthatisprovidedas aparameter.

Started–Occurswhenaudioinputhasbeenstarted.StartedEventArgsobjectthatis providedasa parameter,containsthreepublicfields:BitsPerSample,ChannelCountandSamplesPerSecond.

Stopped–Occurswhenaudioinputhasbeenstopped.

18.4Usage(WinForms)

This chapterdescribestheusageofWinFormsversionofAudioInputclass.WPFversionwillbehandledinchapter17.5.

18.4.1Creation

CreateanewAudioInputinstanceeitherbymanuallyin yoursourcecodeorbydraggingand

droppingitfromVisualStudio’stoolboxonto yourform,usercontroletc.

If youdonotneedtoshowthe GUI(i.e. youuseyourown oryoucontrolAudioInputobjectfromyoursourcecode)then setVisiblepropertyfalse.Parentpropertyisalwaysrecommendedtosetso that whentheparentcontrolis disposedof,AudioInputinstancegetsdisposedof automatically.If thereisnoparentthendonotforgettocallDisposemethodwhen youaredonewithAudioInputinstance.Note,ifyoucreatea newAudioInputinstanceviaVisualStudio’stoolboxthenParentis automaticallyset.

It isrecommendedto setLicenseKeypropertyso thatyourAudioInputinstanceusesanexplicitlicensekeyinsteadoftryingtofindonefromWindows’registry.Note,ifyouareusingatrial version/licensethenyoucanleaveLicenseKeypropertytoitsdefaultvalue.

18.4.2Eventhandling

TogetnewsamplesfromAudioInputinstanceyouneedtosubscribeatleasttoDataGeneratedevent.WhenDataGeneratedeventistriggeredyoucangetthenewsamplesandthefirstsampletimestampfromaDataGeneratedEventArgsobjectprovidedasa parameter.

If youwanttoknowwhenAudioInputinstancehasstarteditsaudiosamplingtaskyousubscribeto Started event.Youcangetthe numberofbits persample,isaudiomonoorstereoandhowmanysamplesper secondaregeneratedfromStartedEventArgsobjectthatisprovidedasa parameter.

If youwanttoknowwhenAudioInputinstancehasstoppedyousubscribetoStoppedevent.Ithasnoparametersanditssolepurposeistotelluserwheneverythinghas beenstopped.