ultrawidify/js/modules/ArDetect.js

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class ArDetector {
constructor(videoData){
this.conf = videoData;
this.video = videoData.video;
this.setupTimer = null;
this.timer = null;
this.sampleCols = [];
// todo: dynamically detect the following two
this.canFallback = true;
this.fallbackMode = false;
this.blackLevel = ExtensionConf.arDetect.blackLevel_default;
}
init(){
if(Debug.debug){
console.log("[ArDetect::init] Initializing autodetection")
}
this.setup(ExtensionConf.arDetect.hSamples, ExtensionConf.arDetect.vSamples);
}
destroy(){
this.debugCanvas.destroy();
}
setup(cwidth, cheight){
this.guardLine = new GuardLine(this);
this.edgeDetector = new EdgeDetect(this);
this.debugCanvas = new DebugCanvas(this);
if(Debug.debug){
console.log("[ArDetect::setup] Starting autodetection setup");
}
if(!cwidth){
cwidth = ExtensionConf.arDetect.hSamples;
cheight = ExtensionConf.arDetect.vSamples;
}
try{
if(Debug.debug){
console.log("[ArDetect::setup] Trying to setup automatic aspect ratio detector. Choice config bits:\ncanvas dimensions:",cwidth, "×", cheight, "\nvideoData:", this.conf);
}
this._halted = false;
this.detectionTimeoutEventCount = 0;
// // vstavimo začetne stolpce v this.sampleCols. - NE!
// // let's insert initial columns to this.sampleCols - NO!!! do it later dow
// this.sampleCols = [];
// var samplingIntervalPx = parseInt(cheight / ExtensionConf.arDetect.samplingInterval)
// for(var i = 1; i < ExtensionConf.arDetect.samplingInterval; i++){
// this.sampleCols.push(i * samplingIntervalPx);
// }
if(this.canvas){
if(Debug.debug)
console.log("[ArDetect::setup] existing canvas found. REMOVING KEBAB removing kebab\n\n\n\n(im hungry and you're not authorized to have it)");
this.canvas.remove();
if(Debug.debug)
console.log("[ArDetect::setup] canvas removed");
}
// imamo video, pa tudi problem. Ta problem bo verjetno kmalu popravljen, zato setup začnemo hitreje kot prej
// we have a video, but also a problem. This problem will prolly be fixed very soon, so setup is called with
// less delay than before
if(this.video.videoWidth === 0 || this.video.videoHeight === 0 ){
if(Debug.debug){
console.log("[ArDetector::setup] video has no width or height!", this.video.videoWidth,"×", this.video.videoHeight)
}
this.scheduleInitRestart();
return;
}
// things to note: we'll be keeping canvas in memory only.
this.canvas = document.createElement("canvas");
this.canvas.width = cwidth;
this.canvas.height = cheight;
this.context = this.canvas.getContext("2d");
// do setup once
// tho we could do it for every frame
this.canvasScaleFactor = cheight / this.video.videoHeight;
try{
// determine where to sample
var ncol = ExtensionConf.arDetect.staticSampleCols;
var nrow = ExtensionConf.arDetect.staticSampleRows;
var colSpacing = this.canvas.width / ncol;
var rowSpacing = (this.canvas.height << 2) / nrow;
this.sampleLines = [];
this.sampleCols = [];
for(var i = 0; i < ncol; i++){
if(i < ncol - 1)
this.sampleCols.push(Math.round(colSpacing * i));
else{
this.sampleCols.push(Math.round(colSpacing * i) - 1);
}
}
for(var i = 0; i < nrow; i++){
if(i < ncol - 5)
this.sampleLines.push(Math.round(rowSpacing * i));
else{
this.sampleLines.push(Math.round(rowSpacing * i) - 4);
}
}
}
catch(ex){
console.log("%c[ArDetect::_arSetup] something went terribly wrong when calcuating sample colums.", ExtensionConf.colors.criticalFail);
console.log("settings object:", Settings);
console.log("error:", ex);
}
// we're also gonna reset this
this.guardLine.top = null;
this.guardLine.bottom = null;
this.resetBlackLevel();
this._forcehalt = false;
// if we're restarting ArDetect, we need to do this in order to force-recalculate aspect ratio
this.conf.resizer.setLastAr({type: "auto", ar: null});
this.canvasImageDataRowLength = cwidth << 2;
this.noLetterboxCanvasReset = false;
this.start();
}
catch(ex){
console.log(ex);
}
if(Debug.debugCanvas.enabled){
this.debugCanvas.init({width: cwidth, height: cheight});
// DebugCanvas.draw("test marker","test","rect", {x:5, y:5}, {width: 5, height: 5});
}
this.conf.arSetupComplete = true;
}
start(){
console.log("%c[ArDetect::setup] Starting automatic aspect ratio detection.", _ard_console_start);
this._halted = false;
this.scheduleFrameCheck(0, true);
}
stop(){
if(Debug.debug){
console.log("%c[ArDetect::_ard_stop] Stopping automatic aspect ratio detection", _ard_console_stop);
}
this._forcehalt = true;
this._halted = true;
clearTimeout(this.setupTimer);
clearTimeout(this.timer);
}
isRunning(){
return ! this._halted;
}
scheduleInitRestart(timeout, force_reset){
if(! timeout){
timeout = 100;
}
// don't allow more than 1 instance
if(this.setupTimer){
clearTimeout(this.setupTimer);
}
var ths = this;
this.setupTimer = setTimeout(function(){
ths.setupTimer = null;
try{
ths.init();
}catch(e){console.log("[ArDetector::scheduleInitRestart] Failed to start init(). Error:",e)}
ths = null;
},
timeout
);
}
scheduleFrameCheck(timeout, force_reset){
if(! timeout){
this.frameCheck();
return;
}
// run anything that needs to be run after frame check
this.postFrameCheck();
// don't allow more than 1 instance
if(this.timer){
clearTimeout(this.timer);
}
var ths = this;
// console.log(this.video, "this.video | ths.video", ths.video)
// console.log(this.conf.video, "this.conf | ths.conf", ths.conf.video)
// console.log("resizer conf&vid",
// this.conf.resizer, this.conf.resizer.conf, this.conf.resizer.video, this.conf.resizer.conf.video )
// debugger;
this.timer = setTimeout(function(){
ths.timer = null;
try{
ths.frameCheck();
}catch(e){console.log("Frame check failed. Error:",e)}
ths = null;
},
timeout
);
}
postFrameCheck(){
if(Debug.debugCanvas.enabled){
this.debugCanvas.update();
}
}
//#region helper functions (general)
attachCanvas(canvas){
if(this.attachedCanvas)
this.attachedCanvas.remove();
// todo: place canvas on top of the video instead of random location
canvas.style.position = "absolute";
canvas.style.left = "200px";
canvas.style.top = "1200px";
canvas.style.zIndex = 10000;
document.getElementsByTagName("body")[0]
.appendChild(canvas);
}
canvasReadyForDrawWindow(){
if(Debug.debug)
console.log("%c[ArDetect::_ard_canvasReadyForDrawWindow] (?)", "color: #44f", this.canvas.height == window.innerHeight, "(ard_height:", this.canvas.height, "| window height:", window.innerHeight, ")");
return this.canvas.height == window.innerHeight
}
getTimeout(baseTimeout, startTime){
var execTime = (performance.now() - startTime);
if( execTime > ExtensionConf.arDetect.autoDisable.maxExecutionTime ){
this.detectionTimeoutEventCount++;
if(Debug.debug){
console.log("[ArDetect::getTimeout] Exec time exceeded maximum allowed execution time. This has now happened " + this.detectionTimeoutEventCount + " times in a row.");
}
// if( this.detectionTimeoutEventCount >= ExtensionConf.arDetect.autoDisable.consecutiveTimeoutCount ){
// if (Debug.debug){
// console.log("[ArDetect::getTimeout] Maximum execution time was exceeded too many times. Automatic aspect ratio detection has been disabled.");
// }
// Comms.sendToBackgroundScript({cmd: 'disable-autoar', reason: 'Automatic aspect ratio detection was taking too much time and has been automatically disabled in order to avoid lag.'});
// _ard_stop();
// return 999999;
// }
} else {
this.detectionTimeoutEventCount = 0;
}
// return baseTimeout > ExtensionConf.arDetect.minimumTimeout ? baseTimeout : ExtensionConf.arDetect.minimumTimeout;
return baseTimeout;
}
//#endregion
processAr(edges){
if(Debug.debug && Debug.debugArDetect){
console.log("[ArDetect::_ard_processAr] processing ar. sample width:", this.canvas.width, "; sample height:", this.canvas.height, "; edge top:", edges.top);
}
// if we don't specify these things, they'll have some default values.
if(edges.top === undefined){
edges.top = 0;
edges.bottom = 0;
edge.left = 0;
edges.right = 0;
}
var letterbox = edges.top + edges.bottom;
var trueHeight = this.canvas.height - letterbox;
if(this.fallbackMode){
if(edges.top > 1 && edges.top <= ExtensionConf.arDetect.fallbackMode.noTriggerZonePx ){
console.log("Edge is in the no-trigger zone. Aspect ratio change is not triggered.")
return;
}
// varnostno območje, ki naj ostane črno (da lahko v fallback načinu odkrijemo ožanje razmerja stranic).
// x2, ker je safetyBorderPx definiran za eno stran.
// safety border so we can detect aspect ratio narrowing (21:9 -> 16:9).
// x2 because safetyBorderPx is for one side.
trueHeight += (ExtensionConf.arDetect.fallbackMode.safetyBorderPx << 1);
}
var trueAr = this.canvas.width / trueHeight;
this.detectedAr = trueAr;
// poglejmo, če se je razmerje stranic spremenilo
// check if aspect ratio is changed:
var lastAr = this.conf.resizer.getLastAr();
if( lastAr.type == "auto" && lastAr.ar != null){
// spremembo lahko zavrnemo samo, če uporabljamo avtomatski način delovanja in če smo razmerje stranic
// že nastavili.
//
// we can only deny aspect ratio changes if we use automatic mode and if aspect ratio was set from here.
var arDiff = trueAr - lastAr.ar;
if (arDiff < 0)
arDiff = -arDiff;
var arDiff_percent = arDiff / trueAr;
// ali je sprememba v mejah dovoljenega? Če da -> fertik
// is ar variance within acceptable levels? If yes -> we done
if(Debug.debug && Debug.debugArDetect)
console.log("%c[ArDetect::_ard_processAr] new aspect ratio varies from the old one by this much:\n","color: #aaf","old Ar", lastAr.ar, "current ar", trueAr, "arDiff (absolute):",arDiff,"ar diff (relative to new ar)", arDiff_percent);
if (arDiff < trueAr * ExtensionConf.arDetect.allowedArVariance){
if(Debug.debug && Debug.debugArDetect)
console.log("%c[ArDetect::_ard_processAr] aspect ratio change denied — diff %:", "background: #740; color: #fa2", arDiff_percent)
return;
}
else if(Debug.debug && Debug.debugArDetect){
console.log("%c[ArDetect::_ard_processAr] aspect ratio change accepted — diff %:", "background: #153; color: #4f9", arDiff_percent)
}
}
if(Debug.debug)
console.log("[ArDetect::_ard_processAr] attempting to fix aspect ratio. New aspect ratio: ", trueAr);
// POMEMBNO: GlobalVars.lastAr je potrebno nastaviti šele po tem, ko kličemo _res_setAr(). _res_setAr() predvideva,
// da želimo nastaviti statično (type: 'static') razmerje stranic — tudi, če funkcijo kličemo tu oz. v ArDetect.
//
// IMPORTANT NOTE: GlobalVars.lastAr needs to be set after _res_setAr() is called, as _res_setAr() assumes we're
// setting a static aspect ratio (even if the function is called from here or ArDetect).
this.conf.resizer.setAr(trueAr, {type: "auto", ar: trueAr});
}
frameCheck(){
// console.log("this.video:", this.video, this.conf.video);
// debugger;
if(this._halted)
return;
if(! this.video){
if(Debug.debug || Debug.warnings_critical)
console.log("[ArDetect::_ard_vdraw] Video went missing. Destroying current instance of videoData.")
this.conf.destroy();
return;
}
var fallbackMode = false;
var startTime = performance.now();
var baseTimeout = ExtensionConf.arDetect.timer_playing;
var triggerTimeout;
var guardLineResult = true; // true if success, false if fail. true by default
var imageDetectResult = false; // true if we detect image along the way. false by default
var sampleCols = this.sampleCols.slice(0);
var how_far_treshold = 8; // how much can the edge pixel vary (*4)
if(this.video.ended ){
// we slow down if ended. Detecting is pointless.
this.scheduleFrameCheck(ExtensionConf.arDetect.timer_paused);
return false;
}
if(this.video.paused){
// če je video pavziran, še vedno skušamo zaznati razmerje stranic - ampak bolj poredko.
// if the video is paused, we still do autodetection. We just do it less often.
baseTimeout = ExtensionConf.arDetect.timer_paused;
}
try{
this.context.drawImage(this.video, 0,0, this.canvas.width, this.canvas.height);
}
catch(ex){
if(Debug.debug)
console.log("%c[ArDetect::_ard_vdraw] can't draw image on canvas. Trying canvas.drawWindow instead", "color:#000; backgroud:#f51;", ex);
try{
if(! ExtensionConf.arDetect.fallbackMode.enabled)
throw "fallbackMode is disabled.";
if(this.canvasReadyForDrawWindow()){
this.context.drawWindow(window, this.canvasDrawWindowHOffset, 0, this.canvas.width, this.canvas.height, "rgba(0,0,128,1)");
if(Debug.debug)
console.log("%c[ArDetect::_ard_vdraw] canvas.drawImage seems to have worked", "color:#000; backgroud:#2f5;");
this.fallbackMode = true;
}
else{
// canvas needs to be resized, so let's change setup
this.stop();
var newCanvasWidth = window.innerHeight * (this.video.videoWidth / this.video.videoHeight);
var newCanvasHeight = window.innerHeight;
if(ExtensionConf.miscFullscreenSettings.videoFloat == "center")
this.canvasDrawWindowHOffset = Math.round((window.innerWidth - newCanvasWidth) * 0.5);
else if(ExtensionConf.miscFullscreenSettings.videFloat == "left")
this.canvasDrawWindowHOffset = 0;
else
this.canvasDrawWindowHOffset = window.innerWidth - newCanvasWidth;
this.setup(newCanvasWidth, newCanvasHeight);
return;
}
}
catch(ex){
if(Debug.debug)
console.log("%c[ArDetect::_ard_vdraw] okay this didnt work either", "color:#000; backgroud:#f51;", ex);
this.scheduleFrameCheck( ExtensionConf.arDetect.timer_error );
return;
}
}
if (! this.blackLevel) {
if(Debug.debugArDetect)
console.log("[ArDetect::_ard_vdraw] black level undefined, resetting");
this.resetBlackLevel();
}
// we get the entire frame so there's less references for garbage collection to catch
var image = this.context.getImageData(0, 0, this.canvas.width, this.canvas.height).data;
if(Debug.debugCanvas.enabled){
this.debugCanvas.setBuffer(image);
}
//#region black level detection
// fast test to see if aspect ratio is correct. If we detect anything darker than blackLevel, we modify
// blackLevel to the new lowest value
var isLetter=true;
var currentMaxVal = 0;
var currentMax_a;
var currentMinVal = 48; // not 255 cos safety, even this is prolly too high
var currentMin_a;
var rowOffset = 0;
var colOffset_r, colOffset_g, colOffset_b;
// detect black level. if currentMax and currentMin vary too much, we automatically know that
// black level is bogus and that we aren't letterboxed. We still save the darkest value as black level,
// though — as black bars will never be brighter than that.
for(var i = 0; i < sampleCols.length; ++i){
colOffset_r = sampleCols[i] << 2;
colOffset_g = colOffset_r + 1;
colOffset_b = colOffset_r + 2;
currentMax_a = image[colOffset_r] > image[colOffset_g] ? image[colOffset_r] : image[colOffset_g];
currentMax_a = currentMax_a > image[colOffset_b] ? currentMax_a : image[colOffset_b];
currentMaxVal = currentMaxVal > currentMax_a ? currentMaxVal : currentMax_a;
currentMin_a = image[colOffset_r] < image[colOffset_g] ? image[colOffset_r] : image[colOffset_g];
currentMin_a = currentMin_a < image[colOffset_b] ? currentMin_a : image[colOffset_b];
currentMinVal = currentMinVal < currentMin_a ? currentMinVal : currentMin_a;
}
// we'll shift the sum. math says we can do this
rowOffset = this.canvas.width * (this.canvas.height - 1);
for(var i = 0; i < sampleCols.length; ++i){
colOffset_r = (rowOffset + sampleCols[i]) << 2;
colOffset_g = colOffset_r + 1;
colOffset_b = colOffset_r + 2;
currentMax_a = image[colOffset_r] > image[colOffset_g] ? image[colOffset_r] : image[colOffset_g];
currentMax_a = currentMax_a > image[colOffset_b] ? currentMax_a : image[colOffset_b];
currentMaxVal = currentMaxVal > currentMax_a ? currentMaxVal : currentMax_a;
currentMin_a = image[colOffset_r] < image[colOffset_g] ? image[colOffset_r] : image[colOffset_g];
currentMin_a = currentMin_a < image[colOffset_b] ? currentMin_a : image[colOffset_b];
if(currentMinVal == undefined && currenMinVal != undefined)
currentMinVal = currentMin_a;
else if(currentMin_a != undefined)
currentMinVal = currentMinVal < currentMin_a ? currentMinVal : currentMin_a;
}
// save black level only if defined
if(currentMinVal)
this.blackLevel = this.blackLevel < currentMinVal ? this.blackLevel : currentMinVal;
//#endregion
// this means we don't have letterbox
if ( currentMaxVal > (this.blackLevel + ExtensionConf.arDetect.blackbarTreshold) || (currentMaxVal - currentMinVal) > ExtensionConf.arDetect.blackbarTreshold ){
// Če ne zaznamo letterboxa, kličemo reset. Lahko, da je bilo razmerje stranic popravljeno na roke. Možno je tudi,
// da je letterbox izginil.
// If we don't detect letterbox, we reset aspect ratio to aspect ratio of the video file. The aspect ratio could
// have been corrected manually. It's also possible that letterbox (that was there before) disappeared.
if(Debug.debug){
console.log("%c[ArDetect::_ard_vdraw] no edge detected. canvas has no edge.", "color: #aaf");
}
// Pogledamo, ali smo že kdaj ponastavili CSS. Če še nismo, potem to storimo. Če smo že, potem ne.
// Ponastavimo tudi guardline (na null).
// let's chec if we ever reset CSS. If we haven't, then we do so. If we did, then we don't.
// while resetting the CSS, we also reset guardline top and bottom back to null.
if(! this.noLetterboxCanvasReset){
this.conf.resizer.reset({type: "auto", ar: null});
this.guardLine.top = null;
this.guardLine.bottom = null;
this.noLetterboxCanvasReset = true;
}
triggerTimeout = this.getTimeout(baseTimeout, startTime);
this.scheduleFrameCheck(triggerTimeout); //no letterbox, no problem
return;
}
// Če preverjamo naprej, potem moramo postaviti to vrednost nazaj na 'false'. V nasprotnem primeru se bo
// css resetiral enkrat na video/pageload namesto vsakič, ko so za nekaj časa obrobe odstranejene
// if we look further we need to reset this value back to false. Otherwise we'll only get CSS reset once
// per video/pageload instead of every time letterbox goes away (this can happen more than once per vid)
this.noLetterboxCanvasReset = false;
// let's do a quick test to see if we're on a black frame
// TODO: reimplement but with less bullshit
// poglejmo, če obrežemo preveč.
// let's check if we're cropping too much (or whatever)
var guardLineOut;
guardLineOut = this.guardLine.check(image, fallbackMode);
if (guardLineOut.blackbarFail) { // add new ssamples to our sample columns
for(var col of guardLineOut.offenders){
sampleCols.push(col)
}
}
// če ni padla nobena izmed funkcij, potem se razmerje stranic ni spremenilo
// if both succeed, then aspect ratio hasn't changed.
// if we're in fallback mode and blackbar test failed, we restore CSS
if (fallbackMode && guardLineOut.blackbarFail) {
this.conf.resizer.reset({type: "auto", ar: null});
this.guardLine.reset();
this.noLetterboxCanvasReset = true;
triggerTimeout = this.getTimeout(baseTimeout, startTime);
this.scheduleFrameCheck(triggerTimeout); //no letterbox, no problem
return;
}
if (!guardLineOut.imageFail && !guardLineOut.blackbarFail) {
triggerTimeout = this.getTimeout(baseTimeout, startTime);
this.scheduleFrameCheck(triggerTimeout); //no letterbox, no problem
return;
}
// će se razmerje stranic spreminja iz ožjega na širšega, potem najprej poglejmo za prisotnostjo navpičnih črnih obrob.
// če so prisotne navpične obrobe tudi na levi in desni strani, potlej obstaja možnost, da gre za logo na črnem ozadju.
// v tem primeru obstaja nevarnost, da porežemo preveč. Ker obstaja dovolj velika možnost, da bi porezali preveč, rajši
// ne naredimo ničesar.
//
// če je pillarbox zaznan v primeru spremembe iz ožjega na širše razmerje stranice, razmerje povrnemo na privzeto vrednost.
//
// If aspect ratio changes from narrower to wider, we first check for presence of pillarbox. Presence of pillarbox indicates
// a chance of a logo on black background. We could cut easily cut too much. Because there's a somewhat significant chance
// that we will cut too much, we rather avoid doing anything at all. There's gonna be a next chance.
try{
if(guardLineOut.blackbarFail || guardLineOut.imageFail){
if(this.edgeDetector.findBars(image, null, EdgeDetectPrimaryDirection.HORIZONTAL).status === 'ar_known'){
if(Debug.debug && guardLineOut.blackbarFail){
console.log("[ArDetect::_ard_vdraw] Detected blackbar violation and pillarbox. Resetting to default aspect ratio.");
}
if(guardLineOut.blackbarFail){
this.conf.resizer.reset({type: "auto", ar: null});
this.guardLine.reset();
}
triggerTimeout = this.getTimeout(baseTimeout, startTime);
this.scheduleFrameCheck(triggerTimeout);
return;
}
}
}catch(e) {console.log("deeee",e)}
// pa poglejmo, kje se končajo črne letvice na vrhu in na dnu videa.
// let's see where black bars end.
this.sampleCols_current = sampleCols.length;
// blackSamples -> {res_top, res_bottom}
var edgePost = this.edgeDetector.findBars(image, sampleCols, EdgeDetectPrimaryDirection.VERTICAL, EdgeDetectQuality.IMPROVED, guardLineOut);
// console.log("SAMPLES:", blackbarSamples, "candidates:", edgeCandidates, "post:", edgePost,"\n\nblack level:",GlobalVars.arDetect.blackLevel, "tresh:", this.blackLevel + ExtensionConf.arDetect.blackbarTreshold);
if(edgePost.status == "ar_known"){
// zaznali smo rob — vendar pa moramo pred obdelavo še preveriti, ali ni "rob" slučajno besedilo. Če smo kot rob pofočkali
// besedilo, potem to ni veljaven rob. Razmerja stranic se zato ne bomo pipali.
// we detected an edge — but before we process it, we need to check if the "edge" isn't actually some text. If the detected
// edge is actually some text on black background, we shouldn't touch the aspect ratio. Whatever we detected is invalid.
// var textEdge = false;;
// if(edgePost.guardLineTop != null){
// var row = edgePost.guardLineTop + ~~(this.canvas.height * ExtensionConf.arDetect.textLineTest.testRowOffset);
// textEdge |= textLineTest(image, row);
// }
// if(edgePost.guardLineTop != null){
// var row = edgePost.guardLineTop - ~~(this.canvas.height * ExtensionConf.arDetect.textLineTest.testRowOffset);
// textEdge |= textLineTest(image, row);
// }
// if(!textEdge){
this.processAr(edgePost);
// we also know edges for guardline, so set them
this.guardLine.setBlackbar({top: edgePost.guardLineTop, bottom: edgePost.guardLineBottom});
// }
// else{
// console.log("detected text on edges, dooing nothing")
// }
triggerTimeout = this.getTimeout(baseTimeout, startTime);
this.scheduleFrameCheck(triggerTimeout); //no letterbox, no problem
return;
} else {
triggerTimeout = this.getTimeout(baseTimeout, startTime);
this.scheduleFrameCheck(triggerTimeout); //no letterbox, no problem
return;
}
}
resetBlackLevel(){
this.blackLevel = ExtensionConf.arDetect.blackLevel_default;
}
}
if(Debug.debug)
console.log("Loading: ArDetect");
var _ard_console_stop = "background: #000; color: #f41";
var _ard_console_start = "background: #000; color: #00c399";
var textLineTest = function(image, row){
// preverimo, če vrstica vsebuje besedilo na črnem ozadju. Če ob pregledu vrstice naletimo na veliko sprememb
// iz črnega v ne-črno, potem obstaja možnost, da gledamo besedilo. Prisotnost take vrstice je lahko znak, da
// zaznano razmerje stranic ni veljavno
//
// vrne 'true' če zazna text, 'false' drugače.
//
//
// check if line contains any text. If line scan reveals a lot of changes from black to non-black there's a
// chance we're looking at text on a black background. If we detect text near what we think is an edge of the
// video, there's a good chance we're about to incorrectly adjust the aspect ratio.
//
// returns 'true' if text is detected, 'false' otherwise
var blackbarTreshold = this.blackLevel + ExtensionConf.arDetect.blackbarTreshold;
var nontextTreshold = this.canvas.width * ExtensionConf.arDetect.textLineTest.nonTextPulse;
var rowStart = (row * this.canvas.width) << 2;
var rowEnd = rowStart + (this.canvas.width << 2);
var pulse = false;
var currentPulseLength = 0, pulseCount = 0;
var pulses = [];
var longestBlack = 0;
// preglejmo vrstico
// analyse the row
for(var i = rowStart; i < rowEnd; i+= 4){
if(pulse){
if(image[i] < blackbarTreshold || image[i+1] < blackbarTreshold || image[i+2] < blackbarTreshold){
// pulses.push(currentPulseLength);
pulseCount++;
pulse = false;
currentPulseLength = 0;
}
else{
currentPulseLength++;
// če najdemo dovolj dolgo zaporedje ne-črnih točk, potem vrnemo 'false' — dobili smo legitimen rob
// if we find long enough uninterrupted line of non-black point, we fail the test. We found a legit edge.
if(currentPulseLength > nontextTreshold){
return false;
}
}
}
else{
if(image[i] > blackbarTreshold || image[i+1] > blackbarTreshold || image[i+2] > blackbarTreshold){
if(currentPulseLength > longestBlack){
longestBlack = currentPulseLength;
}
pulse = true;
currentPulseLength = 0;
}
else{
currentPulseLength++;
}
}
}
if(pulse){
pulseCount++;
// pulses.push(currentPulseLength);
}
// pregledamo rezultate:
// analyse the results
// console.log("pulse test:\n\npulses:", pulseCount, "longest black:", longestBlack);
// če smo zaznali dovolj pulzov, potem vrnemo res
// if we detected enough pulses, we return true
if(pulseCount > ExtensionConf.arDetect.textLineTest.pulsesToConfirm){
return true;
}
// če je najdaljša neprekinjena črta črnih pikslov širša od polovice širine je merilo za zaznavanje
// besedila rahlo milejše
// if the longest uninterrupted line of black pixels is wider than half the width, we use a more
// forgiving standard for determining if we found text
if( longestBlack > (this.canvas.width >> 1) &&
pulseCount > ExtensionConf.arDetect.textLineTest.pulsesToConfirmIfHalfBlack ){
return true;
}
// če pridemo do sem, potem besedilo ni bilo zaznano
// if we're here, no text was detected
return false;
}