TW2835比较完整版本

QCIF全称Quartercommonintermediateformat。QCIF是常用的标准化图像格式。在H.323协议簇中，规定了视频采集设备的标准采集分辨率。QCIF=176×144像素。CIF是常用的标准化图像格式（CommonIntermediateFormat）。在H.323协议簇中，规定了视频采集设备的标准采集分辨率。CIF=352×288像素CIF格式具有如下特性：

(1)电视图像的空间分辨率为家用录像系统(VideoHomeSystem，VHS)的分辨率，即352×288。

(2)使用非隔行扫描(non-interlacedscan)。

(3)使用NTSC帧速率，电视图像的最大帧速率为30000/1001≈29.97幅/秒。

(4)使用1/2的PAL水平分辨率，即288线。

(5)对亮度和两个色差信号(Y、Cb和Cr)分量分别进行编码，它们的取值范围同ITU-RBT.601。即黑色=16，白色=235，色差的最大值等于240，最小值等于16。

下面为5种CIF图像格式的参数说明。参数次序为“图象格式亮度取样的象素个数(dx)亮度取样的行数(dy)色度取样的象素个数(dx/2)色度取样的行数(dy/2)”。sub-QCIF128×966448QCIF

176×1448872CIF

352×2881761444CIF

704×576352288（即我们经常说的D1）16CIF

1408×1152704576目前监控行业中主要使用Qcif（176×144）、CIF（352×288）、HALFD1（704×288）、D1

（704×576）等几种分辨率，CIF录像分辨率是主流分辨率，绝大部分产品都采用CIF分辨率。目前市场接受CIF分辨率，主要理由有四点：1、目前数码监控要求视频码流不能太高；2、视频传输带宽也有限制；3、使用HALFD1、D1分辨率可以提高清晰度，满足高质量的要求，但是以高码流为代价的。在现阶段，出现了众多D1的产品，但市场份额非常小；4、采用CIF分辨率，信噪比在32db以上，一般用户是可以接受的，但不是理想的视频图像质量。目前业内人士正在尝试用HALFD1来寻求CIF、D1之间的平衡。但随着单块硬盘的容量达到750GB甚至1000GB，而国内的大部分DVR已经可以做到连接8块1000GB的硬盘，故D1逐渐会变成时常的主流。DCIF分辨率是什么？经过研究发现一种更为有效的监控视频编码分辨率（DCIF），其像素为528×384。DCIF分辨率的是视频图像来历是将奇、偶两个HALFD1，经反隔行变换，组成一个D1（720*576），D1作边界处理，变成4CIF（704×576），4CIF经水平3/4缩小、垂直2/3缩小，转换成528×384.528×384的像素数正好是CIF像素数的两倍，为了与常说的2CIF（704*288）区分，我们称之为DOUBLECIF，简称DCIF。显然，DCIF在水平和垂直两个方向上，比HalfD1更加均衡。

为什么选用DCIF分辨率？

数字化监控行业对数字监控产品提出两项要求：首先要求数据量低，保证系统能够长时间录像和稳定实时的网络传输；其次要求回放图像清晰度高，满足对细节的要求。而DCIF分辨率在目前的软硬件平台上，能很好的满足以上两项要求。

HalfD1分辨率已被部分产品采用，用来解决CIF清晰度不够高和D1存储量高、价格高昂的缺点。但由于他相对于CIF只是水平分辨率的提升，图像质量提高不是特别明显，但码流增加很大。

经过对大量视频信号进行测试，基于目前的视频压缩算法，DCIF分辨率比HalfD1能更好解决CIF清晰度不够高和D1存储量高、价格高昂的缺点，用来解决CIF和4CIF，特别是在512Kbps码率之间，能获得稳定的高质量图像，满足用户对较高图像质量的要求，为视频编码提供更好的选择。

CIF清晰度不够高和D1存储量高、价格高昂的缺点分辨率，静态回放分辨率理论上最高可达360TVline的图像质量，超过模拟监控中标准VHS磁带录像机280TVline的图像水平，达到公安部安防行业视频标准二级和三级项目的清晰度要求，满足绝大部分视频监控的要求。什么是D1？做闭路电视监控系统这一行久了，大家都以为D1是硬盘录像机显示、录像、回放的分辨率，实际上不是的，D1是数字电视系统显示格式的标准，共分为以下5种规格：D1：480i格式（525i）：720×480（水平480线，隔行扫描），和NTSC模拟电视清晰度相同，行频为15.25kHz，相当于我们所说的4CIF（720×576）D2：480P格式（525p）：720×480（水平480线，逐行扫描），较D1隔行扫描要清晰不少，和逐行扫描DVD规格相同，行频为31.5kHzD3：1080i格式（1125i）：1920×1080（水平1080线，隔行扫描），高清放松采用最多的一种分辨率，分辨率为1920×1080i/60Hz，行频为33.75kHzD4：720p格式（750p）：1280×720（水平720线，逐行扫描），虽然分辨率较D3要低，但是因为逐行扫描，市面上更多人感觉相对于1080I（实际逐次540线）视觉效果更加清晰。不过个人感觉来说，在最大分辨率达到1920×1080的情况下，D3要比D4感觉更加清晰，尤其是文字表现力上，分辨率为1280×720p/60Hz，行频为45kHzD5：1080p格式（1125p）：1920×1080（水平1080线，逐行扫描），目前民用高清视频的最高标准，分辨率为1920×1080P/60Hz,行频为67.5KHZ。其中D1和D2标准是我们一般模拟电视的最高标准，并不能称的上高清晰，D3的1080i标准是高清晰电视的基本标准，它可以兼容720p格式，而D5的1080P只是专业上的标准，并不是民用级别的，上面所给出的60HZ只是理想状态下的场频，而它的行频为67.5KHZ，目前还没有如此高行频的电视问世，实际在专业领域里1080P的场频只有24HZ，25HZ和30HZ。

需要指出的一点是，D端子是日本独有的特殊接口，国内电视几乎没有带这种接口的，最多的是色差接口，而色差接口最多支持到D4，理论上肯定没有HDMI（纯数字信号，支持到1080P)的最高清晰度高，但在1920：1080以下分辨率的电视机上，一般也没有很大差别。国内主流的硬盘录像机（DVR，DigitalVideoRecording）采用什么分辨率？怎样计算硬盘容量？国内主流的硬盘录像机采用两种分辨率：CIF和4CIF（D1），分为两种型号。

硬盘录像机常见的路数有1路、2路、4路、8路、9路、12路和16路。最大可以连接8块2000GB的硬盘，总容量可高达1.6TB（可续目前市面上最大的硬盘只有1000GB），如果采用CIF分辨率，通常计算硬盘录像机的录像的硬盘容量为180MB~250MB/小时，通常情况下取值200MB/小时；如果是D1的分辨率每小时录像需要的硬盘容量为720MB~1000MB/小时，通常情况下为了减少硬盘的容量可以按照500MB/小时计算，帧率智能设置比25fps少一些，码流也要少一些！相信大家可以计算出一台装满8块500GB的16路硬盘录像机可以录像多长时间了吧？TW2835将6个主要程序整合进一个芯片中，其中包括：4个高质量的NTSC/PAL视频解码器、4个音频模拟数字转换器、一个音频复用器，双色显示控制器，双视频译码器以及一个先进的OSD（屏幕菜单式调节方式）。在其众多功能中，TW2835支持详尽的实时D1录制、在重放过程中将信道ID信息添加到视频流媒体中，用于自动解码与显示，同时还包含一个5层的图形覆盖功能，为OSD（屏幕菜单式调节方式）、单盒、2D阵列箱以及鼠标指示器显示特征/位图。TW2835还包含一个简单的界面，使用多段连接支持多达16个信道系统。此外，TW2835还嵌入了几种特别的监视功能，其中包括：运动监测、放大以及水平与垂直缩放控制。凭借置入旨在减少交叉噪音的反锯齿过滤器和高质量的梳状过滤器，TW2835已经成为一种针对DVR（数码视频录像机）与Quad/Multiplexers的高性能、具有成本效益的解决方案。IntroductionBlockDiagram:FunctionalDescription:VideoInput:ITU-RBT656=CCIR656ITU-RBT656:9芯，不需要同步信号；8位数据传输；串行视频传输；传输速率是601的2倍；先传Y，后传UV。656输出的是串行数据，行场同步信号嵌入在数据流中;601是并行数据，行场同步有单独输出;The656usethe4:2:2videocodingprotocol.Thedatasignalsareintheformofbinaryinformationcodedin8-bitwords.Thesesignalsare:

–videodata;

–timingreferencecodes;

–ancillarydata;(辅助数据)

–identificationcodes.

Dataformat:ABT.656datastreamisasequenceof8-bitor10-bitbytes,transmittedatarateof27Mbyte/s.Horizontalscanlinesofvideopixeldataaredelimitedinthestreamby4-bytelongSAV(StartofActiveVideo)andEAV(EndofActiveVideo)codesequences.SAVcodesalsocontainstatusbitsindicatinglinepositioninavideofieldorframe.LinepositioninafullframecanbedeterminedbytrackingSAVstatusbits,allowingreceiversto'synchronize'withanincomingstream.IndividualpixelsinalinearecodedinYCbCrformat.AfteraSAVcode(4bytes)issent,thefirst8bitsofY(luma)dataaresentthen8bitsofCb(chromaU),followedby8bitsofYforthenextpixelandthen8bitsofCr(chromaV).ToreconstructcompleteY,Cb,Crpixelvalues,chromasubsamplingmustbeusedThe656onlysupportthe4:2:2。The656samplingrateis27M。

The656hasembedded(thedigitaldataincludethecodinginformationforHsVsandField)Sync(CalledVideoTimingReferenceCodesSAV,EAV),656hasfieldinformations.Analogvideoinput:支持所以的NTSC/PAL视频标准，包含有自动标准检测电路。该电路可以被覆盖当写IFMTMAN和IFORMAT寄存器。如果检测到视频损耗，将被迫运行由IFORMAT寄存器知道的视频标准模式。表1显示TW2835支持的视频输入标准：Anti-aliasingFilter:带宽6MHz.Analog-to-DigitalConverter(数模转换):10bitADC.每个ADC有2个模拟开关由ANA_SW寄存器控制。ADC也可进入低功耗模式由ADC_PWDN寄存器控制。SyncProcessing（同步处理）：用于在混合视频信号中检测水平和垂直的同步信号。水平同步处理器包含同步分离器，PLL，相关逻辑。同步分离器通过低通滤波，附加的逻辑来避免假检测。PLL来防止抖动。垂直同步分离器检测垂直同步信号。场状态由垂直同步时间来决定。当检测到垂直信号的位置和水平同步信号一致，它暗示了帧的起始或是奇数场的开始。否则，表示偶数场。ColorDecoding（色彩编码）：色度和亮度分离由自适应的梳状滤波器是实现。色度TrapFilter（陷波滤波器）来调整视觉性能：对于NTSC陷波频率为3.5MHz，PAL陷波频率为4.5MHz左右。LuminanceProcessing（亮度处理）：亮度信号由自适应梳状滤波器分离得到，并输送到峰化电路。峰化电路加强亮度信号的高频分量通过Y_PEAK寄存器。图片对比度调整通过CONT寄存器，调整范围0-200%亮度的调整通过BRT寄存器，调整范围±25IRE。ChrominanceProcessing（色度处理）：为NTSC和PAL第一个正交混频来实现色度解调。混频=NTSC和PAL的子载波频率。在混频后，LPF用于除去载波的2倍频和场色度分量。若IF（中频）源失调，则，IF补偿滤波器来补偿在高频的衰减或者在色度子载波附近的不对称性。色度上边带增益由IFCOMP寄存器来控制。ACC(自动色度增益控制)用于补偿在视频信号中由于高频抑制引起的降低色度幅度。大致增益范围：-6dB到30dB。对于黑白视频或者弱噪声信号，内部的色彩killer电路将关闭色彩。Colorkillingfunction能够由可编程的CKIL寄存器使能。色彩饱和度可由SAT寄存器来改变。Cb、Cr增益可分别由UGAIN和VGAIN寄存器来调整。Cb、Croffset可由U_OFF和V_OFF寄存器调整。色相（HUE）可由HUE寄存器来调整。要调节的参数相应的寄存器饱和度SAT（0x08,0x18,0x28,0x38）Cb、CrGainUGAIN(0x48)、VGAIN(0x49)Cb、CrOffsetU_OFF(0x4A)、V_OFF(0x4B)HUEHUE(0x07,0x17,0x27,0x37)Real-timeRecordMode（实时记录模式）:4个channelReal-timerecordoutputswithfullD1formatthroughtheDLINK1andMPP1/2pins.并支持H/V/F信号。DLINK1和MPP1/2pins通过MPP_MD(1xB0)和MPP_SET(1xB1,1xB3,1xB5)寄存器控制。DigitalVideoInput：用于playback支持8bitITU-RBT.656standard。ChannelIDdecoder用于autocroppingandstrobefunction.ChannelIDDecoder:3kindsofchannelID:UserchannelID,DetectionchannelID,andautochannelID.TheUserchannelIDisusedforcustomizedinformationlikesysteminformationanddate.TheDetectionchannelIDisusedfordetectedinformationofcurrentliveinputsuchasmotion,videoloss,blindandnightdetectioninformation.TheautochannelIDisemployedforautomaticidentificationofpictureconfigurationwhichincludesthechannelnumber,analogswitch,event,regionenableandfield/framemodeinformation.TheTW2835alsosupportsbothanaloganddigitaltypechannelIDduringVBIperiod.ThedigitalchannelIDhaspriorityoveranalogchannelID.VBI是VerticalBlankingInterval的缩写，中文意思是场消隐期，也叫场逆程。电视节目称为正程信号。在625/25的电视信号中，可以利用的电视行从第6/318行开始至第22/334行止，每场最多可插入17个数据行。VBI采集就是指对场消隐期中的数据采集。TheanalogtypechannelIDdecodingisenabledviatheVBI_ENA(1x86)register.ThedigitaltypechannelIDdecodingisoperatedviaVBI_CODE_EN(1x86)register.AdditionallytodetectproperlytheanalogchannelIDagainstnoisesuchasVCRsource,thechannelIDLPFcanbeenabledviatheVBI_FLT_EN(1x86)register.ThedecodedchannelIDinformationisusedforautocropping/strobefunctionandcanalsobereadthroughthehostinterface.channelIDdetectionmode支持automatic和manual（手动）。ForanautomaticchannelIDdetectionmode,theplaybackinputshouldincludearun-inclock.ButforamanualchannelIDdetectionmode,theplaybackinputcanincludearun-inclockornotviaVBI_RIC_ON(1x88)register.Inamanualdetectionmode,theTW2835hasseveralrelatedregistersuchastheVBI_PIXEL_HOS(1x87)todefinehorizontalstartoffset,theVBI_FLD_OS(1x88)todefinelineoffsetbetweenoddandevenfield,theVBI_PIXEL_HWtodefinepulsewidthfor1bitdata,theVBI_LINE_SIZE(1x89)todefinechannelIDlinesizeandtheVBI_LINE_OS(1x89)todefinelineoffsetforchannelID.TheVBI_MID_VAL(1x8A)registerisusedtodefinethethresholdlevelbetweenhighandlow.EveninautomaticchannelIDdetectionmode,thelinesizeandbitwidthcanbediscriminatedbyreadingtheVBI_LINE_SIZEandVBI_PIXEL_HW(1xCB)register.TheFig10showstherelationshipbetweenchannelIDandregistersetting.ThischannelIDinformationcanbereadthroughtheCHID_TYPEorCHID_VALID(1x8B),AUTO_CHID0/1/2/3(1x8C~1x8F),DET_CHID0/1/2/3/4/5/6/7(1x98~1x9F),andUSER_CHID0/1/2/3/4/5/6/7(1x90~1x97)registers.TheCHID_TYPEregisterdiscriminatesbetweentheAutochannelID(CHID_TYPE=“1”)andUserchannelID(CHID_TYPE=“0”).TheCHID_VALIDregisterindicateswhetherthedetectedchannelIDtypeisvalidornot.TheAUTO_CHID,DET_CHIDandUSER_CHIDregistersareusedtocheckthedecodedchannelIDdatawhentheVBI_RD_CTL(1x88)registervalueis“1”.BasicallythechannelIDislocatedinVBIperiodandautostrobeandcroppingisexecutedafterchannelIDdecoding.Butforsomecase,thechannelIDcanbeplacedinverticalactiveperiodinsteadofVBIperiod.Forthismode,theTW2835alsosupportsthechannelIDdecodingfunctionwithinverticalactiveperiodviatheVAV_CHK(1x89)registerandmanualcroppingfunctionviatheMAN_PBCROP(0xC0)registerwithproperVDELAYvalue.CroppingandScalingFunctionScalingfunction提供在低分辨率下的视频图像当croppingfunction提高一部分的视频图像。TW2835也支持自动croppingfunction为playbackinputwithchannelIDdecoding.TW2835有个freescaler用于variableimagesizeindisplaypath，buthasalimitationofimagesizeinrecordpathsuchasFull/QUAD/CIFformat.CroppingFunctionforLiveThecroppingfunctionallowsonlysubsectionofavideoimagetobeoutput.TheactivevideoregionisdeterminedbytheHDELAY,HACTIVE,VDELAYandVACTIVE(0x02~0x06,0x12~0x16,0x22~0x26,0x32~0x36)register.ThefirstactivelineisdefinedbytheVDELAYregisterandthefirstactivepixelisdefinedbytheHDELAYregister.TheVACTIVEregistercanbeprogrammedtodefinethenumberofactivelinesinavideofieldtheHACTIVEregistercanbeprogrammedtodefinethenumberofactivepixelsinavideoline.Thisfunctionisusedtoimplementforpanning（平移）andtilt（倾斜）.HDELAY+HACTIVE<TotalnumberofpixelsperlineWherethetotalnumberofpixelsperlineis858forNTSCand864forPAL全屏大小：theHDELAYshouldbesetto32andHACTIVEsetto720forbothNTSCandPALsystem.VDELAY+VACTIVE<TotalnumberoflinesperfieldWherethetotalnumberoflinesperfieldis262forNTSCand312forPAL全屏大小：NTSCPALVDELAY65VACTIVE240288theVDELAYshouldbesetto6andVACTIVEsetto240forNTSCandtheVDELAYshouldbealsosetto5andVACTIVEsetto288forPAL.ScalingFunctionforLiveScaler用于displaypath.不能用于recordpath.BecausechannelsizedefinitionforrecordpathhasalimitationsuchasFull/QUAD/CIF(Pleasereferto“RecordPathControl”section,page64).亮度水平scaler包括anti-aliasingfiltertoreduceimageartifactsintheresizedimageviatheHSFLT(0x80/90/A0/B0,0x85/95/A5/B5and0x8A/9A/AA/BA)registeranda32poly-phasefiltertoaccuratelyinterpolatethevalueofapixel.垂直scaleralsocontainsananti-aliasingfiltercontrolledviatheVSFLT(0x80/90/A0/B0,0x85/95/A5/B5and0x8A/9A/AA/BA)registerand16poly-phasefiltersfordownscaling.DownscalingisachievedbyprogrammingthescalingregisterHSCALEandVSCALE(0x81~0x84,0x91~0x94,0xA1~0xA4,0xB1~0xB4)register.Whennoscaledvideoimage,theTW2835willoutputthenumberofpixelsasspecifiedbytheHACTIVEandVACTIVE(0x02~0x06,0x12~0x16,0x22~0x26,0x32~0x36)register.IfthenumberofoutputpixelsrequiredissmallerthanthenumberspecifiedbytheHACTIVE/VACTIVEregister,the16bitHSCALE/VSCALEregisterisusedtoreducetheoutputpixelstothedesirednumber.Thefollowingequationisusedtodeterminethehorizontalscalingratiotobewrittenintothe16bitHSCALEregister.HSCALE=[Npixel_desired/HACTIVE]*(2^16–1)(例子在32页)WhereNpixel_desiredisthedesirednumberofactivepixelsperlineThefollowingequationisusedtodeterminetheverticalscalingratiotobewrittenintothe16bitVSCALEregister.VSCALE=[Nline_desired/VACTIVE]*(2^16-1)(例子在32页)WhereNline_desiredisthedesirednumberofactivelinesperfieldCroppingandScalingFunctionforPlaybackanautocroppingfunctionwithchannelIDdecodingforplaybackinput.IfthePB_AUTO_EN(1x16)=“0”,theTW2835issettoamanualcroppingmodesothatusercancontrolcroppingwithVDELAY_PBandHDELAY_PB(0x8B~0x8F,0x9B~9F,0xAB~AFand0xBB~BF)register.IfthePB_AUTO_EN=“1”,theTW2835issetintoanautocroppingmode.Inthismode,thedesiredchannelcanbechosenbyPB_CH_NUMregister(1x16,1x1E,1x26,1x2E)anditwillbecroppedautomaticallytohorizontalandverticaldirectioninplaybackinput.TheTW2835hasseveralrelatedregistersforthismodesuchasPB_CROP_MD,PB_ACT_MDandMAN_PBCROP(0xC0).ThePB_CROP_MDdefinestherecordmodeoftheplaybackinputsuchasnormalrecordmodeorDVRrecordmode(Pleasereferto“RecordPathControl”section,page64).ThePB_ACT_MDdefinesanactivepixelsizeofhorizontaldirectionsuchas720/704/640pixels.TheMAN_PBCROPcontrolsthehorizontalandverticalstartingoffsetintheautocroppingmodewithHDELAY_PBandVDELAY_PBregisters.ItisusefulincasethattheencodedchannelIDislocatedatverticalactiveareainITU-RBT.656datastream.TheTW2835includesfouradditionalfreedownscalarsforplaybackpathsothatthevideoimagefromplaybackinputcanbedownscaledtoanarbitrarysizeinbothhorizontalandverticaldirection.Therefore,usingthiscroppingandscalingfunction,theTW2835supportsfreesizeandpositioningfunctionforbothliveandplaybackinputindisplaypath.MotionDetectionTheTW2835supportsmotiondetectorindividuallyfor4analogvideoinputs.TheTW2835alsosupportsblindandnightinputdetectionfor4analogvideoinputs.TheTW2835为每个运动检测器提供了许多灵敏度和速度的控制参数TheTW2835supportsmanualstrobefunctiontoupdatemotiondetectionsothatitismoreappropriateforuser-definedmotionsensitivitycontrol.Whenmotion,blindandnightinputaredetectedinanyvideoinputs,theTW2835providestheinterruptrequesttohostviatheIRQpin.（72管脚）Thehostprocessorcantaketheinformationofmotion,blindornightdetectionbyaccessingtheIRQENA_MD(1x79),IRQENA_BD(1x7A)andtheIRQENA_ND(1x7B)register.Thisstatusinformationisupdatedintheverticalblankperiodofeachinput.TheTW2835alsoprovidesthemotion,blindandnightdetectionresultthroughtheDLINKIandMPP0/1pinwiththecontrolofMPP_MD(1xB0)andMPP_SET(1xB1,1xB3and1xB5)register.TheTW2835supportsanoverlayfunctiontodisplaythemotiondetectionresultinthepicturewith2Darrayedbox.MaskandDetectionRegionSelectionThemotiondetectionalgorithmutilizesthefullscreenvideodataanddetectsindividualmotionof16x12cells.Thisfullscreenformotiondetectionconsistsof704pixelsand240linesforNTSCand288linesforPAL.Startingpixelinhorizontaldirectioncanbeshiftedfrom0to15pixelsusingtheMD_ALIGN(2x82,2xA2,2xC2,and2xE2)register.EachcellcanbemaskedviatheMD_MASK(2x86~2x9D,2xA6~2xBD,2xC6~2xDD,2xE6~2xFD)registerasillustratedinFig16.Ifthemaskbitinspecificcellisprogrammedtohigh,therelatedcellisignoredformotiondetection.MD_MASK寄存器的介绍在37页。运动检测的原理就是把全屏的数据分为16X12的小单元。TheMD_MASKregisterhasdifferentfunctionforreadingandwritingmode.Forwritingmode,setting“1”toMD_MASKregisterinhibitsthespecificcellfromdetectingmotion.Forreadingmode,theMD_MASKregisterhasthreekindsofinformationdependingontheMASK_MODE(2x82,2xA2,2xC2,and2xE2)register.ForMASK_MODE=“0”,thestateofMD_MASKregistermeanstheresultofVIN_Amotiondetectionthat“1”indicatesdetectingmotionand“0”denotesnomotiondetectioninthecell.ForMASK_MODE=“1”,thestateofMD_MASKregistermeanstheresultofVIN_Bmotiondetection.ForMASK_MODE=“2or3”,thestateofMD_MASKregistermeansmaskinginformationofcell.SensitivityControlThemotiondetectorhas4sensitivityparameterstocontrolthresholdofmotiondetectionsuchasthelevelsensitivityviatheMD_LVSENS(2x83,2xA3,2xC3,and2xE3)register,thespatialsensitivityviatheMD_SPSENS(2x85,2xA5,2xC5,2xE5)andMD_CELSENS(2x83,2xA3,2xC3,and2xE3)register,andthetemporalsensitivityparameterviatheMD_TMPSENS(2x85,2xA5,2xC5,and2xE5)register.LevelSensitivitythemotionisdetectedwhenluminanceleveldifferencebetweencurrentandreferencefieldisgreaterthanMD_LVSENSvalue.MD_LVSENS不能设置的太小不然就太灵敏，抗噪声就弱了，当然也不能设置太大，不然灵敏度就太低了。。。SpatialSensitivityTheTW2835uses192(16x12)detectioncellsinfullscreenformotiondetection.Eachdetectioncelliscomposedof44pixelsand20linesforNTSCand24linesforPAL.Motiondetectionfromonlyluminanceleveldifferencebetweentwofieldsisveryweakinspatialrandomnoise.Toremovethefakemotiondetectionfromtherandomnoise,theTW2835supportsaspatialfilterviatheMD_SPSENSregisterwhichdefinesthenumberofdetectedcelltodecidemotiondetectioninfullsizeimage.ThelargeMD_SPSENSvalueincreasestheimmunityofspatialrandomnoise.Eachdetectioncellhas4sub-cellsalso.Actuallymotiondetectionofeachcellcomesfromcomparisonofsub-cellsinit.TheMD_CELSENSdefinesthenumberofdetectedsub-celltodecidemotiondetectionincell.Thatis,thelargeMD_CELSENSvalueincreasestheimmunityofspatialrandomnoiseindetectioncell.TemporalSensitivityTheMD_TMPSENSregulatesthenumberoftapsinthetemporalfiltertocontrolthetemporalsensitivitysothatthelargeMD_TMPSENSvalueincreasestheimmunityoftemporalrandomnoise.VelocityControl运动有不同的速度。在fastmotion,在相邻的场间，物体快速的出现和消失。Slowmotion就相反了。因为只采用两个相邻场的亮度水平的差别，所以slowmotion在检测速度上比fastmotion低。为了弥补这个缺点，MD_SPEED(2x84,2xA4,2xC4,and2xE4)parameterisusedwhichiscontrollableupto64fields.MD_SPEEDparameteradjuststhefieldintervalinwhichtheluminanceleveliscompared.Thus,fordetectionofafastmotionasmallvalueisneededandforaslowmotionalargevalueisrequired.MD_SPEED的值要大于MD_TMPSENSvalue.Additionally,theTW2835has2moreparameterstocontroltheselectionofreferencefield.TheMD_FLD(2x82,2xA2,2xC2,and2xE2)registerisafieldselectionparametersuchasodd,even,anyfieldorframe.TheMD_REFFLD(2x80,2xA0,2xC0,and2xE0)registerisprovidedtocontroltheupdatingperiodofreferencefield.即参考场的变化由MD_REFFLD。ForMD_REFFLD=“0”,theintervalfromcurrentfieldtoreferencefieldisalwayssameastheMD_SPEED.Itmeansthatthereferencefiledisalwaysupdatedeveryfield.TheTW2835alsosupportsthemanual（手动）detectiontimingcontrolofthereferencefield/frameviatheMD_STRB_ENandMD_STRB(2x84,2xA4,2xC4,and2xE4)register.ForMD_STRB_EN=“0”,thereferencefield/frameisautomaticallyupdatedandreservedoneveryreferencefield/frame.ForMD_STRB_EN=“1”,thereferencefield/frameisupdatedandreservedonlywhenMD_STRB=“1”.Inthismode,theintervalbetweencurrentandreferencefield/framedependsonuser’sstrobetiming.Thismodeisveryusefulforaspecificpurposelikenon-periodicalvelocitycontrolandveryslowmotiondetection.TheTW2835alsoprovidesdualdetectionmodefornon-real-timeapplicationsuchaspseudo-8chapplicationviaMD_DUAL_EN(2x83,2xA3,2xC3,and2xE3)register.ForMD_DUAL_EN=1,theTW2835candetectdualmotionindependentlyforVIN_AandBInputwhichisdefinedbytheANA_SW(0x0D,0x1D,0x2D,and0x3D)register.Inthiscase,theMD_SPEEDislimitedto31.ThismotioninformationcanbereadviatheIRQENA_MD(1x79)registerbythehostinterface.BlindDetectionIndividuallyfor4analogvideoinputsandmakesaninterruptofblinddetectiontohost.2个灵敏度参数来检测blind：thelevelsensitivitytheBD_LVSENS(2x80,2xA0,2xC0,and2xE0)registerthespatialsensitivitytheBD_CELSENS(2x80,2xA0,2xC0,and2xE0)register.TheTW2835usestotal768(32x24)cellsinfullscreenforblinddetection.TheBD_LVSENSparametercontrolsthethresholdoflevelbetweencellandfieldaverage.TheBD_CELSENSparameterdefinesthenumberofcellstodetectblind.ForBD_CELSENS=“0”,thenumberofcellwhoselevelissameasaverageoffieldshouldbeoverthan60%todetectblind,70%forBD_CELSENS=“1”,80%forBD_CELSENS=“2”,and90%forBD_CELSENS=“3”.Thatis,thelargevalueofBD_LVSENSandBD_CELSENSmakesblinddetectorlesssensitive.TheTW2835alsosupportsdualdetectionmodefornon-real-timeapplicationsuchaspseudo-8chapplicationviatheMD_DUAL_EN(2x83,2xA3,2xC3,and2xE3)register.ThehostcanreadblinddetectioninformationforbothVIN_AandVIN_BinputviatheIRQENA_BD(1x7A)register.NightDetectionindividuallyfor4analogvideoinputsandmakesaninterruptofnightdetectiontohost.2个灵敏度参数来检测night:thelevelsensitivitytheND_LVSENS(2x81,2xA1,2xC1,and2xE1)registerthetemporalsensitivitytheND_TMPSENS(2x81,2xA1,2xC1,and2xE1)register.TheND_LVSENSparametercontrolsthresholdlevelofdayandnight.TheND_TMPSENSparameterregulatesthenumberoftapsinthetemporallowpassfiltertocontrolthetemporalsensitivity.ThelargevalueofND_LVSENSandND_TMPSENSmakesnightdetectorlesssensitive.TheTW2835alsosupportsdualdetectionmodefornon-real-timeapplicationsuchaspseudo-8chapplicationviatheMD_DUAL_EN(2x83,2xA3,2xC3,and2xE3)register.ThehostcanreadnightdetectioninformationforbothVIN_AandVIN_BinputviatheIRQENA_ND(1x7B)register.VideoControlTheTW2835hasdualvideocontrollersfordisplayandrecordpath.TheTW2835requiresonlyexternal64MSDRAM@32bitinterfaceforproperoperation.8个channeldisplaymodefordisplaypath4个channelsforrecordpathTheblockdiagramofvideocontrollerisshowninthefollowingFig19.TheTW2835supportschannelblanking（消隐，熄灭）,boundary（分界线）on/off,blink（闪烁）,horizontal/verticalmirroring,andfreezefunctionforeachchannel.TheTW2835cancapturelast4imagesautomaticallyforeachchannelwhenvideolossisdetected.3种operationmode操作模式：live,strobeandswitchmodeEachchannelcanbeoperatedinitsindividualoperatingmode.Thatis,theTW2835canbeoperatedinmulti-operatingmodeifeachchannelhasdifferentoperatingmode.LivemodeisusedtodisplayrealtimevideoasQUADorfulllivedisplay.Strobemodeisusedtodisplaynon-real-timevideowithstrobesignalfromhost.Switchmodeisusedtodisplaytime-multiplexedvideofromseveralchannels.Forswitchmode,theTW2835supportstwodifferenttypessuchasswitchliveandswitchstillmode.TheTW2835alsoprovidesfourrecordpicturemodes:normalrecordmodeframerecordmodeDVRnormalrecordmodeDVRframerecordmodeForrecordpath,channelsizeandpositionhavealimitationtohalforfullsizeinthehorizontalandverticaldirection.Fordisplaypath,theTW2835cansaveandrecallvideothroughexternalextendedSDRAMandsupportimageenhancementfunctionfornon-real-timevideosuchasfreezingorplaybackvideoandprovidehighperformance2Xzoomfunction.Forrecordpath,theTW2835supportsanoisereductionfiltertoreducethecompressiondatasizeandchannelIDencodingthatcontainsallcurrentpictureconfigurations.TheTW2835alsoprovideschip-to-chipcascadeconnectionfor8or16channelapplication.ChannelInputSelectionThechannelfordisplaypathcanselect1inputfrom8videoinputsincluding4livevideoinputsand4playbackinputs,butthechannelforrecordpathcanchoose1inputfrom4livevideoinputs.ThelivevideoinputscanbeselectedviatheDEC_PATH(0x80,0x90,0xA0,0xB0fordisplaypath,1x60,1x63,1x66,1x69forrecordpath)registerandtheplaybackinputscanbechosenviathePB_PATH_EN(1x10/13,1x18/1B,1x20/23,1x28/2B)register.TheFig20showstheinternalchannelinputselection.ChannelOperationMode每个信道都能够运行在三种模式：live，strobe，switchmode通过配置theFUNC_MODE(1x10,1x13,1x18,1x1B,1x20,1x23,1x28,and1x2Bfordisplaypath,1x60,1x63,1x66,and1x69forrecordpath)register.Theoperationmodecanbeselectedindividuallyforeachchannelsothatmulti-operatingmodecanbeimplemented.LiveModeIfFUNC_MODEis“0”,channelisoperatedinlivemode.Forthelivemode,thevideodisplayisupdatedwithrealtime.ThismodeisusedtodisplayalivevideosuchasQUAD,PIP,andPOP.Whenchangingthepictureconfigurationsuchasinputpath,popuppriority,PIP,POP,andetc,theTW2835supportsanti-rollingsequencebymonitoringchannelupdatewiththeSTRB_REQregister(1x01fordisplaypath,1x54forrecordpath)afterchangingtostrobeoperationmode(FUNC_MODE=“1”).ThefollowingFig21showsthesequencetochangepictureconfiguration.FUNC_MODE=“0”：livemode FUNC_MODE=“1”：strobemode FUNC_MODE=“2”：switchmodeThestatusofSTRB_REQregistercanalsobereadthroughMPP1/2pinwithcontroloftheMPPMDandMPPSET(1xB0,1xB1,1xB3,and1xB5)register.StrobeModeIfFUNC_MODEis“1”,channelisoperatedinstrobemode.在strobemode下，视频显示更新在TW2835接收到strobe命令的时候。如果Host没有发送strobe命令，那么信道保持最后的strobe图像直到得到新的strobe命令。这种模式用于显示非实时视频输入，如：视频回放playbackVideowith多路复用信号的输入multiplexedsignalinput也为了实现toimplementpseudo8channel应用或者dualpagemodeorpanorama（全景）channeldisplay.Specially,theTW2835supportseasyinterfaceforpseudo8channelapplicationthatwillbecoveredindisplaypathcontrolsection.TheTW2835alsosupportsautostrobefunctionforautoplaybackdisplaythatwillbecoveredlaterinautostrobefunctionsection.StrobeoperationisperformedindependentlyforeachchannelviatheSTRB_REQ(1x04,1x54)register.ButtheSTRB_REQregisterhasadifferentmodeforreadingandwriting.Writing“1”intoSTRB_REQineachchannelmakestheTW2835updatedbyeachincomingvideo.TheupdatingstatusafterstrobecommandcanbeknownbyreadingtheSTRB_REQregister.Ifreadingvalueis“1”,updatingisnotcompletedaftergettingthestrobecommand.Inthatcase,thischannelcannotacceptanewstrobecommandoradisablingstrobecommandfromhos