Support for auto-generated captions in Playlet backend

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 
 - Spanish translations (Thanks to Kamborio)
+- Support for auto-generated captions in Playlet backend
 
 ## [0.28.0] - 2024-10-13
 

playlet-lib/src/components/Services/Innertube/InnertubeService.bs

@@ -246,7 +246,7 @@ namespace InnertubeService
             "hlsUrl": streamingData["hlsManifestUrl"]
             "adaptiveFormats": []
             "formatStreams": []
-            "captions": []
+            "captions": ParseCaptions(payload)
             "recommendedVideos": []
         }
 
@@ -256,6 +256,66 @@ namespace InnertubeService
         }
     end function
 
+    function ParseCaptions(payload as object) as object
+        captions = payload["captions"]
+        if not IsAssociativeArray(captions)
+            return []
+        end if
+
+        playerCaptions = captions["playerCaptionsTracklistRenderer"]
+        if not IsAssociativeArray(playerCaptions)
+            return []
+        end if
+
+        tracks = playerCaptions["captionTracks"]
+        if not IsArray(tracks)
+            return []
+        end if
+
+        captions = []
+        for each track in tracks
+            if not IsAssociativeArray(track)
+                continue for
+            end if
+
+            baseUrl = track["baseUrl"]
+            if not IsString(baseUrl)
+                continue for
+            end if
+
+            queryComponents = UrlUtils.ParseQueryComponents(baseUrl)
+            queryComponents["fmt"] = "vtt"
+            baseUrl = UrlUtils.SetQueryParams(baseUrl, queryComponents)
+
+            languageCode = track["languageCode"]
+            if not IsString(languageCode)
+                continue for
+            end if
+
+            label = ""
+            name = track["name"]
+            if IsAssociativeArray(name)
+                runs = name["runs"]
+                if IsArray(runs)
+                    for each rn in runs
+                        text = rn["text"]
+                        if IsString(text)
+                            label += text
+                        end if
+                    end for
+                end if
+            end if
+
+            captions.Push({
+                "label": label
+                "language_code": languageCode
+                "url": baseUrl
+            })
+        end for
+
+        return captions
+    end function
+
     function ParseInnertubeNextResponse(payload as object, parsedResponse as object) as object
         if not parsedResponse.Success
             LogWarn("Invalid parsed response", parsedResponse)

playlet-lib/src/components/VideoPlayer/VideoContentTask.bs

@@ -212,10 +212,15 @@ function SetCaptions(metadata as object, service as object, contentNode as objec
             code = isoLanguageList[code]
         end if
 
+        url = caption.url
+        if not url.StartsWith("http")
+            url = instance + url
+        end if
+
         subtitleTracks.Push({
             Description: caption.label
             Language: code
-            TrackName: instance + caption.url
+            TrackName: url
         })
     end for
 

playlet-lib/src/source/utils/UrlUtils.bs

@@ -8,7 +8,7 @@ namespace UrlUtils
 
     function BuildUrl(url as string, pathParams as object, queryParams as object) as string
         url = SetPathParams(url, pathParams)
-        url = SetQueryParams(url, queryParams)
+        url = AppendQueryParams(url, queryParams)
         return url
     end function
 
@@ -34,6 +34,14 @@ namespace UrlUtils
     end function
 
     function SetQueryParams(url as string, queryParams as object) as string
+        questionMarkIndex = url.InStr("?")
+        if questionMarkIndex <> -1
+            url = url.Left(questionMarkIndex)
+        end if
+        return AppendQueryParams(url, queryParams)
+    end function
+
+    function AppendQueryParams(url as string, queryParams as object) as string
         if queryParams = invalid or queryParams.Count() = 0
             return url
         end if