feat: adaptive bitrate support, engine improvements, demo updates, and electron preload

engine/core/Engine.ts

@@ -132,9 +132,9 @@ export class Engine {
 
     if (this.isInitialScene) {
       this.isInitialScene = false
-      this.videoManager.playInitial(scene.videoUrl, preloadUrls)
+      this.videoManager.playInitial(this.videoManager.resolveVideoUrl(scene, this.videoManager.streamingQuality), preloadUrls)
     } else {
-      this.videoManager.switchTo(scene.videoUrl, preloadUrls)
+      this.videoManager.switchTo(this.videoManager.resolveVideoUrl(scene, this.videoManager.streamingQuality), preloadUrls)
     }
   }
 

engine/core/VideoManager.ts

@@ -12,6 +12,7 @@ export class VideoManager {
   private preloaded: Map<'A' | 'B', string> = new Map()
   private switching = false
   private sceneVideo: HTMLVideoElement | null = null
+  streamingQuality = ''
 
   private get active(): HTMLVideoElement {
     return this.activeSlot === 'A' ? this.elA! : this.elB!
@@ -169,6 +170,30 @@ export class VideoManager {
     if (this.elB) this.elB.muted = muted
   }
 
+  resolveVideoUrl(scene: { videoUrl: string; streamingUrl?: Record<string, string> }, quality?: string): string {
+    const isElectron = typeof window !== 'undefined' && !!(window as any).__ELECTRON__
+    if (!isElectron && scene.streamingUrl) {
+      const key = quality || Object.keys(scene.streamingUrl)[0]
+      return scene.streamingUrl[key] || scene.videoUrl
+    }
+    return scene.videoUrl
+  }
+
+  switchQuality(src: string, seekTime: number) {
+    const active = this.active
+    this.currentSrc = src
+    active.src = src
+    this.preloaded.set(this.keyOf(active), src)
+    this.waitReady(active).then(() => {
+      active.currentTime = seekTime
+      active.play().catch(() => {})
+    })
+  }
+
+  private keyOf(el: HTMLVideoElement): 'A' | 'B' {
+    return el === this.elA ? 'A' : 'B'
+  }
+
   onEnd(cb: VideoEndCallback) {
     this.onEndCallback = cb
   }

engine/types.ts

@@ -21,6 +21,7 @@ export interface SceneNode {
   bgmDuckFade?: number
   videoMuted?: boolean
   skippable?: boolean
+  streamingUrl?: Record<string, string>
 }
 
 export interface Choice {