Add support for timedtext captions (#3533)

src/invidious/routes/api/v1/videos.cr

@@ -93,6 +93,10 @@ module Invidious::Routes::API::V1::Videos
     # as well as some other markup that makes it cumbersome, so we try to fix that here
     if caption.name.includes? "auto-generated"
       caption_xml = YT_POOL.client &.get(url).body
+
+      if caption_xml.starts_with?("<?xml")
+        webvtt = caption.timedtext_to_vtt(caption_xml, tlang)
+      else
         caption_xml = XML.parse(caption_xml)
 
         webvtt = String.build do |str|
@@ -134,15 +138,21 @@ module Invidious::Routes::API::V1::Videos
             END_CUE
           end
         end
+      end
     else
       # Some captions have "align:[start/end]" and "position:[num]%"
       # attributes. Those are causing issues with VideoJS, which is unable
       # to properly align the captions on the video, so we remove them.
       #
       # See: https://github.com/iv-org/invidious/issues/2391
+      webvtt = YT_POOL.client &.get("#{url}&format=vtt").body
+      if webvtt.starts_with?("<?xml")
+        webvtt = caption.timedtext_to_vtt(webvtt)
+      else
         webvtt = YT_POOL.client &.get("#{url}&format=vtt").body
           .gsub(/([0-9:.]{12} --> [0-9:.]{12}).+/, "\\1")
       end
+    end
 
     if title = env.params.query["title"]?
       # https://blog.fastmail.com/2011/06/24/download-non-english-filenames/

src/invidious/videos/caption.cr

@@ -31,6 +31,72 @@ module Invidious::Videos
       return captions_list
     end
 
+    def timedtext_to_vtt(timedtext : String, tlang = nil) : String
+      # In the future, we could just directly work with the url. This is more of a POC
+      cues = [] of XML::Node
+      tree = XML.parse(timedtext)
+      tree = tree.children.first
+
+      tree.children.each do |item|
+        if item.name == "body"
+          item.children.each do |cue|
+            if cue.name == "p" && !(cue.children.size == 1 && cue.children[0].content == "\n")
+              cues << cue
+            end
+          end
+          break
+        end
+      end
+      result = String.build do |result|
+        result << <<-END_VTT
+        WEBVTT
+        Kind: captions
+        Language: #{tlang || @language_code}
+
+
+        END_VTT
+
+        result << "\n\n"
+
+        cues.each_with_index do |node, i|
+          start_time = node["t"].to_f.milliseconds
+
+          duration = node["d"]?.try &.to_f.milliseconds
+
+          duration ||= start_time
+
+          if cues.size > i + 1
+            end_time = cues[i + 1]["t"].to_f.milliseconds
+          else
+            end_time = start_time + duration
+          end
+
+          # start_time
+          result << start_time.hours.to_s.rjust(2, '0')
+          result << ':' << start_time.minutes.to_s.rjust(2, '0')
+          result << ':' << start_time.seconds.to_s.rjust(2, '0')
+          result << '.' << start_time.milliseconds.to_s.rjust(3, '0')
+
+          result << " --> "
+
+          # end_time
+          result << end_time.hours.to_s.rjust(2, '0')
+          result << ':' << end_time.minutes.to_s.rjust(2, '0')
+          result << ':' << end_time.seconds.to_s.rjust(2, '0')
+          result << '.' << end_time.milliseconds.to_s.rjust(3, '0')
+
+          result << "\n"
+
+          node.children.each do |s|
+            result << s.content
+          end
+          result << "\n"
+          result << "\n"
+        end
+      end
+      return result
+    end
+
     # List of all caption languages available on Youtube.
     LANGUAGES = {
       "",