Upload transcript-tracer.js

transcript-tracer.js

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+/*
+
+© 2023 Samuel Bradshaw
+https://github.com/samuelbradshaw/transcript-tracer-js
+
+*/
+
+
+// Global state variables
+var ttIsInitialized = false;
+var ttTranscripts;
+var ttMediaPlayers;
+var ttActivePlayer;
+var ttLinkedDataByMediaUrl = {};
+
+// Configuration variables (see README.md)
+var ttBlockSelector = null;
+var ttPhraseSelector = null;
+var ttAlignmentFuzziness = 0;
+var ttTimeOffset = 0;
+var ttAutoScroll = null;
+var ttClickable = false;
+
+
+// Prepare transcripts and media players
+function loadTranscriptTracer(options=null) {
+  if (document.readyState == 'loading') {
+    // Wait for document to load
+    document.addEventListener('DOMContentLoaded', function() {
+      loadTranscriptTracer(options);
+    });
+    return;
+  }
+  
+  // Save user-provided options to configuration variables
+  if (options) {
+    if ('blockSelector' in options) ttBlockSelector = options.blockSelector;
+    if ('phraseSelector' in options) ttPhraseSelector = options.phraseSelector;
+    if ('alignmentFuzziness' in options) ttAlignmentFuzziness = options.alignmentFuzziness;
+    if ('timeOffset' in options) ttTimeOffset = options.timeOffset;
+    if ('autoScroll' in options) ttAutoScroll = options.autoScroll;
+    if ('clickable' in options) ttClickable = options.clickable;
+  }
+  
+  // Reset Transcript Tracer to prevent unexpected behavior if loadTranscriptTracer() is called more than once
+  if (ttIsInitialized) {
+    if (ttTranscripts) for (const transcript of ttTranscripts) {
+      unlinkTranscript(transcript);
+      transcript.dataset.ttTranscript = '';
+    }
+    ttTranscripts = null;
+    ttMediaPlayers = null;
+    ttActivePlayer = null;
+    ttLinkedDataByMediaUrl = {};
+    document.querySelectorAll('.tt-word, .tt-whitespace').forEach(element => {
+      element.outerHTML = element.innerHTML;
+    });
+  }
+  
+  // Set a few global state variables
+  ttIsInitialized = true;
+  ttTranscripts = document.getElementsByClassName('tt-transcript');
+  ttMediaPlayers = document.querySelectorAll('audio, video');
+
+  // Prepare transcript for alignment by adding spans and classes
+  for (let t = 0; t < ttTranscripts.length; t++) {
+    var transcript = ttTranscripts[t];
+    // Skip transcript if it's not linked to any media files
+    if (!transcript.dataset.ttMediaUrls) continue;
+  
+    transcript.dataset.ttTranscript = t;
+  
+    // Loop through text nodes to add spans (tt-word, tt-whitespace)
+    // Method of iterating text nodes thanks to https://stackoverflow.com/a/34700627/1349044
+    var iter = document.createNodeIterator(transcript, NodeFilter.SHOW_TEXT);
+    var textNode;
+    while (textNode = iter.nextNode()) {
+      const text = textNode.textContent;
+      if (text.replace(/\s/g, '').length != 0) {
+        var spannedText = '<span class="tt-word">' + text.replace(/(\s+)/g, '</span><span class="tt-whitespace">$1</span><span class="tt-word">') + '</span>';
+        spannedText = spannedText.replaceAll('<span class="tt-word"></span>', '');
+        
+        // Replace text node with spanned text
+        const template = document.createElement('template');
+        template.innerHTML = spannedText;
+        textNode.parentNode.insertBefore(template.content, textNode);
+        textNode.parentNode.removeChild(textNode);
+      }
+    }
+  }
+  
+  for (const mediaPlayer of ttMediaPlayers) {
+    // Link related transcript(s)
+    linkTranscripts(mediaPlayer);
+    
+    // Add event listener to media player
+    mediaPlayer.addEventListener('play', function(e) {
+      if (ttActivePlayer != e.currentTarget) {
+        if (ttActivePlayer) {
+          ttActivePlayer.pause();
+          ttActivePlayer.removeEventListener('timeupdate', ttTimeUpdate);
+        }
+        ttActivePlayer = e.currentTarget;
+        if (ttCurrentTranscript) clearHighlightedWords(ttCurrentTranscript);
+        if (ttCurrentEvent) ttCurrentEvent = null;
+      }
+      ttActivePlayer.addEventListener('timeupdate', ttTimeUpdate);
+      var currentTranscript = ttTranscripts[ttLinkedDataByMediaUrl[ttActivePlayer.dataset.ttLinkedMediaUrl].transcriptIndex];
+      currentTranscript.dataset.ttCurrentMediaUrl = ttActivePlayer.dataset.ttLinkedMediaUrl;
+    });
+    mediaPlayer.addEventListener('ended', function(e) {
+      if (ttCurrentTranscript) clearHighlightedWords(ttCurrentTranscript);
+      if (ttCurrentEvent) ttCurrentEvent = null;
+    });
+  }
+}
+
+
+// Link media player to relevant transcripts
+function linkTranscripts(mediaPlayer) {
+  var trackElement = mediaPlayer.querySelector('track[kind="metadata"]')
+
+  var mediaPlayerSourceUrls = [];
+  var mediaPlayerSrc = mediaPlayer.getAttribute('src');
+  var mediaPlayerSourceElements = mediaPlayer.querySelectorAll('source');
+  if (mediaPlayerSrc) mediaPlayerSourceUrls.push(mediaPlayerSrc);
+  if (mediaPlayerSourceElements) for (const s of mediaPlayerSourceElements) mediaPlayerSourceUrls.push(s.src);
+  
+  // If there's nothing to link, return
+  if (!trackElement || !trackElement.getAttribute('src') || mediaPlayerSourceUrls.length == 0) return;
+  
+  // Fetch WebVTT content and link related transcripts
+  for (const transcript of ttTranscripts) {    
+    for (const mediaUrl of mediaPlayerSourceUrls) {
+      if (transcript.dataset.ttMediaUrls.includes(mediaUrl)) {
+        mediaPlayer.dataset.ttLinkedMediaUrl = mediaUrl;
+        unlinkTranscript(transcript);
+        fetch(trackElement.src)
+          .then(r => r.text())
+          .then(vttContent => linkTranscript(mediaPlayer, vttContent, transcript));
+        break;
+      }
+    }
+  }
+
+  function linkTranscript(mediaPlayer, vttContent, transcript) {
+    var wordTimings = parseVttToWordTimings(vttContent);
+    transcript.dataset.ttCurrentMediaUrl = mediaPlayer.dataset.ttLinkedMediaUrl;
+    
+    function normalizedWord(word) {
+      // Convert to lowercase, normalize, and remove anything that's not a letter or number
+      return word.toLowerCase().normalize('NFD').replace(/[^\p{L}\p{N}]/gu, '');
+    }
+    
+    // Add metadata to block and phrase containers (if ttBlockSelector and ttPhraseSelector are defined)
+    var blockContainers = ttBlockSelector ? transcript.querySelectorAll(ttBlockSelector) : [];
+    for (let c = 0; c < blockContainers.length; c++) blockContainers[c].dataset.ttBlock = c;
+    var phraseContainers = ttPhraseSelector ? transcript.querySelectorAll(ttPhraseSelector) : [];
+    for (let c = 0; c < phraseContainers.length; c++) phraseContainers[c].dataset.ttPhrase = c;
+    
+    // Add metadata to each word span, and build timed events list
+    var timedEvents = [];
+    var wordTimingsIndex = 0;
+    var wordSpans = transcript.getElementsByClassName('tt-word');
+    for (let s = 0; s < wordSpans.length; s++) {
+      var span = wordSpans[s];
+    
+      // Find the next word timing object that matches the current span's text            
+      var initialWordTimingsIndex = wordTimingsIndex;
+      var maxFuzzyWordTimingsIndex = Math.min(wordTimingsIndex + ttAlignmentFuzziness, wordTimings.length - 1);
+      while (normalizedWord(span.innerText) != normalizedWord(wordTimings[wordTimingsIndex].text) && wordTimingsIndex <= maxFuzzyWordTimingsIndex) {
+        wordTimingsIndex += 1;
+      }
+      if (normalizedWord(span.innerText) != normalizedWord(wordTimings[wordTimingsIndex].text)) {
+        // Could not find matching word within the fuzziness range
+        wordTimingsIndex = initialWordTimingsIndex;
+        continue;
+      }
+      
+      // Get the block, phrase, and word index
+      blockIndex = ttBlockSelector ? (span.closest(ttBlockSelector)?.dataset?.ttBlock ?? null) : wordTimings[wordTimingsIndex].blockIndex;
+      phraseIndex = ttPhraseSelector ? (span.closest(ttPhraseSelector)?.dataset?.ttPhrase ?? null) : wordTimings[wordTimingsIndex].phraseIndex;
+      wordIndex = wordTimings[wordTimingsIndex].wordIndex;
+      
+      // Add block, phrase, and word index as metadata on the span
+      span.dataset.ttBlock = blockIndex;
+      span.dataset.ttPhrase = phraseIndex;
+      span.dataset.ttWord = wordIndex;
+
+      // Add timed event to timed events list
+      if (timedEvents.length != 0 && wordTimings[wordTimingsIndex].startSeconds == timedEvents[timedEvents.length-1].seconds) {
+        timedEvents[timedEvents.length-1].currentWordIndexes.push(wordIndex);
+      } else {
+        timedEvents.push({
+          'seconds': wordTimings[wordTimingsIndex].startSeconds,
+          'currentWordIndexes': [wordIndex],
+          'phraseIndex': phraseIndex,
+          'blockIndex': blockIndex,
+        });
+      }
+    
+      wordTimingsIndex += 1;
+    }
+
+    // For a given element, find the first parent element containing relevant children
+    function findRelevantParent(startingElement, endingElement, childSelector, relevantChildSelector) {
+      var currentElement = startingElement;
+      while (currentElement && currentElement != endingElement) {
+        var currentElement = currentElement.parentElement;
+        var children = currentElement.querySelectorAll(childSelector);
+        var relevantChildren = document.querySelectorAll(relevantChildSelector);
+        if (children.length == relevantChildren.length) {
+          // Relevant parent found
+          return currentElement;
+        } else if (children.length > relevantChildren.length) {
+          // Failed to find a relevant parent
+          break;
+        }
+      }
+      return null;
+    }
+    
+    // Add metadata to block and phrase containers (if ttBlockSelector and ttPhraseSelector aren't defined)
+    if (!ttBlockSelector) {
+      var count = wordTimings[wordTimings.length-1].blockIndex + 1;
+      for (let c = 0; c < count; c++) {
+        var startingElement = document.querySelector(`[data-tt-block="${c}"]`);
+        var blockContainer = findRelevantParent(startingElement, transcript, '[data-tt-word]', `[data-tt-word][data-tt-block="${c}"]`);
+        if (blockContainer) blockContainer.dataset.ttBlock = c;
+      }
+    }
+    if (!ttPhraseSelector) {
+      var count = wordTimings[wordTimings.length-1].phraseIndex + 1;
+      for (let c = 0; c < count; c++) {
+        var startingElement = document.querySelector(`[data-tt-phrase="${c}"]`);
+        var phraseContainer = findRelevantParent(startingElement, transcript, '[data-tt-word]', `[data-tt-word][data-tt-phrase="${c}"]`);
+        if (phraseContainer) phraseContainer.dataset.ttPhrase = c;
+      }
+    }
+    
+    // Sort timed events list by time
+    timedEvents = timedEvents.sort(function(a, b) { 
+      return a.seconds - b.seconds;
+    })
+    
+    // Add reference data to ttLinkedDataByMediaUrl
+    var transcriptIndex = parseInt(transcript.dataset.ttTranscript);
+    ttLinkedDataByMediaUrl[mediaPlayer.dataset.ttLinkedMediaUrl] = {
+      'transcriptIndex': transcriptIndex,
+      'wordTimings': wordTimings,
+      'timedEvents': timedEvents,
+      'mediaElement': mediaPlayer,
+      'textTrackData': mediaPlayer.textTracks[0],
+    }
+
+    // Add click listeners to words
+    if (ttClickable) {
+      for (const word of document.querySelectorAll('.tt-word')) {
+        word.addEventListener('click', handleWordClick);
+      }
+    }
+  }
+}
+
+
+// Unlink transcript from previous VTT
+function unlinkTranscript(transcript) {
+  clearHighlightedWords(transcript);
+  
+  var ttLinkedElements = transcript.querySelectorAll('[data-tt-word]');
+  for (const element of ttLinkedElements) {
+    element.dataset.ttWord = '';
+    element.dataset.ttPhrase = '';
+    element.dataset.ttBlock = '';
+  }
+  
+  var mediaUrl = transcript.dataset.ttCurrentMediaUrl;
+  if (mediaUrl) {
+    delete ttLinkedDataByMediaUrl[mediaUrl]
+    transcript.dataset.ttCurrentMediaUrl = '';
+  }
+  
+  for (const word of document.querySelectorAll('.tt-word')) {
+    word.removeEventListener('click', handleWordClick);
+  }
+}
+
+
+// Convert WebVTT into a wordTimings list
+function parseVttToWordTimings(vttContent) {
+  var wordTimings = [];
+  
+  // Split WebVTT at each double line break
+  var vttSegments = vttContent.split(/\r?\n\r?\n/);
+  if (vttSegments.length == 0 || !vttSegments[0].startsWith('WEBVTT')) {
+    console.error('Error: Invalid VTT file. See https://developer.mozilla.org/en-US/docs/Web/API/WebVTT_API');
+    return;
+  }
+  
+  // Loop through each segment of the WebVTT
+  // WebVTT documentation: https://developer.mozilla.org/en-US/docs/Web/API/WebVTT_API
+  var cueWordCounter = 0;
+  var cuePhraseCounter = 0;
+  var cueBlockCounter = 0;
+  for (let s = 0; s < vttSegments.length; s++) {
+    var segment = vttSegments[s];
+    
+    // Skip segment if it's not a cue
+    if (segment.startsWith('WEBVTT') || /^STYLE\s/.test(segment) || /^NOTE\s/.test(segment)) continue;
+  
+    // Convert VTT timestamps to seconds
+    function convertVttTimestampToSeconds(vttTimestamp) {
+      var parts = vttTimestamp.trim().split(':');
+      var seconds = 0;
+      if (parts.length == 3) { // 00:02:01.003
+        seconds = (parseFloat(parts[0]) * 60 * 60) + (parseFloat(parts[1]) * 60) + parseFloat(parts[2])
+      } else { // 02:01.003
+        seconds = (parseFloat(parts[0]) * 60) + parseFloat(parts[1])
+      }
+      return seconds;
+    }
+    
+    // Parse cue
+    var cueIdentifier = cuePayload = '';
+    var cueStartSeconds = cueEndSeconds = null;
+    var segmentLines = segment.split(/\r?\n/);
+    for (const line of segmentLines) {
+      if (line.includes('-->')) {
+        // Cue timings (single line)
+        cueStartSeconds = wordStartSeconds = convertVttTimestampToSeconds(line.split('-->')[0].trim());
+        cueEndSeconds = convertVttTimestampToSeconds(line.split('-->')[1].trim());
+      } else if (cueStartSeconds == null) {
+        // Cue identifier (optional)
+        cueIdentifier += line;
+      } else {
+        // Cue payload (may be multiple lines)
+        var adjustedLine = line.replace(/(<\d*:?\d+:\d+\.\d+>)\s/g, ' $1').replace(/(<\d*:?\d+:\d+\.\d+>)(<\d*:?\d+:\d+\.\d+>)/g, '$1 $2');
+        cuePayload += adjustedLine;
+        var cueWords = adjustedLine.split(/\s/)
+        for (let word of cueWords) {
+          var matches = Array.from(word.matchAll(/(^<\d*:?\d+:\d+\.\d+>)?(.+$)/g));
+          if (matches.length == 1 && matches[0][1] != null) {
+            match = matches[0];
+            wordStartSeconds = convertVttTimestampToSeconds(match[1].replace('<', '').replace('>', ''));
+            word = match[2];
+          }
+          
+          // Push word to wordTimings list
+          if (word) {
+            wordTimings.push({
+              'text': word,
+              'startSeconds': wordStartSeconds,
+              'endSeconds': cueEndSeconds,
+              'wordIndex': cueWordCounter,
+              'phraseIndex': cuePhraseCounter,
+              'blockIndex': cueBlockCounter,
+            })
+            cueWordCounter += 1;
+          }
+        }
+        cuePhraseCounter += 1;
+      }
+    }
+    cueBlockCounter += 1;
+  }
+  
+  return wordTimings;
+}
+
+
+// Respond to timeupdate event (progress as the audio or video is playing)
+var ttCurrentTranscript = null;
+var ttPreviousEvent = null;
+var ttCurrentEvent = null;
+var ttNextEvent = null;
+function ttTimeUpdate(e) {
+  // If the current player isn't active or doesn't have data, return
+  if (!ttActivePlayer || e.currentTarget != ttActivePlayer || !(ttActivePlayer.dataset.ttLinkedMediaUrl in ttLinkedDataByMediaUrl)) return;
+  
+  var adjustedCurrentTime = ttActivePlayer.currentTime + (ttTimeOffset * -1);
+  var ttData = ttLinkedDataByMediaUrl[ttActivePlayer.dataset.ttLinkedMediaUrl];
+  
+  // Make sure the correct transcript is selected
+  if (!ttCurrentTranscript || ttCurrentTranscript.dataset.ttTranscript != ttData.transcriptIndex) {
+    ttCurrentTranscript = document.querySelector(`[data-tt-transcript="${ttData.transcriptIndex}"]`);
+  }
+  
+  // If before the first event, after the last event, or within the range of the current event, return
+  if (ttCurrentEvent && (ttCurrentEvent.seconds < ttData.timedEvents[0].seconds || ttCurrentEvent.seconds > ttData.timedEvents[ttData.timedEvents.length-1].seconds)) return;
+  if (ttCurrentEvent && ttNextEvent && ttCurrentEvent.seconds <= adjustedCurrentTime && ttNextEvent.seconds > adjustedCurrentTime) return;
+  
+  // Clear words that were highlighted from the previous event
+  clearHighlightedWords(ttCurrentTranscript);
+  
+  // Add highlights for the current event
+  for (let t = 0; t < ttData.timedEvents.length; t++) {
+    if (ttData.timedEvents[t].seconds <= adjustedCurrentTime && (!ttData.timedEvents[t+1] || adjustedCurrentTime < ttData.timedEvents[t+1]?.seconds)) {
+      
+      ttPreviousEvent = ttData.timedEvents[t-1] || null;
+      ttCurrentEvent = ttData.timedEvents[t];
+      ttNextEvent = ttData.timedEvents[t+1] || null;
+      
+      // Mark blocks
+      if (ttCurrentEvent.blockIndex != null) {
+        var blockElements = ttCurrentTranscript.querySelectorAll(`[data-tt-block="${ttCurrentEvent.blockIndex}"]`);
+        for (let b = 0; b < blockElements.length; b++) blockElements[b].classList.add((b==0 && !blockElements[b].classList.contains('tt-word')) ? 'tt-current-block-container' : 'tt-current-block');
+      }
+      
+      // Mark phrases
+      if (ttCurrentEvent.phraseIndex != null) {
+        var phraseElements = ttCurrentTranscript.querySelectorAll(`[data-tt-phrase="${ttCurrentEvent.phraseIndex}"]`);
+        for (let p = 0; p < phraseElements.length; p++) phraseElements[p].classList.add((p==0 && !phraseElements[p].classList.contains('tt-word')) ? 'tt-current-phrase-container' : 'tt-current-phrase');
+      }
+      
+      // Mark words
+      if (ttCurrentEvent.currentWordIndexes.length > 0) {
+        for (const wordIndex of ttCurrentEvent.currentWordIndexes) {
+          var wordElements = ttCurrentTranscript.querySelectorAll(`[data-tt-word="${wordIndex}"]`);
+          for (const wordElement of wordElements) wordElement.classList.add('tt-current-word');
+        }
+        for (const wordElement of ttCurrentTranscript.getElementsByClassName('tt-word')) {
+          if (wordElement.classList.contains('tt-current-word')) break;
+          wordElement.classList.add('tt-previous-word');
+        }
+      }
+      
+      // Auto-scroll to the highlighted text
+      if (ttAutoScroll) {
+        var scrollOptions = { behavior: 'smooth', block: 'start', inline: 'nearest' }
+        if (ttAutoScroll == 'block' && ttPreviousEvent?.blockIndex != ttCurrentEvent.blockIndex) {
+          document.querySelector('.tt-current-block-container').scrollIntoView(scrollOptions);
+        } else if (ttAutoScroll == 'phrase' && ttPreviousEvent?.phraseIndex != ttCurrentEvent.phraseIndex) {
+          document.querySelector('.tt-current-phrase-container').scrollIntoView(scrollOptions);
+        } else if (ttAutoScroll == 'word') {
+          document.querySelector('.tt-current-word').scrollIntoView(scrollOptions);
+        }
+      }
+      
+      break;
+    }
+  }
+}
+
+
+// Clear highlighted words in transcript
+function clearHighlightedWords(transcript) {
+  if (!transcript) return;
+  var ttHighlightedElements = transcript.querySelectorAll('[class*="tt-current"], [class*="tt-previous"]');
+  for (const element of ttHighlightedElements) {
+    element.classList.remove('tt-current-block', 'tt-current-block-container', 'tt-current-phrase', 'tt-current-phrase-container', 'tt-current-word', 'tt-previous-word');
+  }
+}
+
+
+// Handle when a word in the transcript with an event listener is clicked
+function handleWordClick(e) {
+  var wordElement = e.currentTarget;
+  var wordIndex = wordElement.dataset.ttWord;
+  var transcript = wordElement.closest('.tt-transcript');
+  var mediaUrl = transcript.dataset.ttCurrentMediaUrl;
+  var startSeconds = ttLinkedDataByMediaUrl[mediaUrl].wordTimings[wordIndex].startSeconds
+  ttLinkedDataByMediaUrl[mediaUrl].mediaElement.currentTime = startSeconds;
+}