feat: batch video upscaling with folder upload, directory save, and result comparison (#1051)

* feat: support batch video upscaling with folder upload and directory save

- Add multi-file selection and entire folder upload (webkitdirectory)
- Support drag & drop of both files and folders via FileSystemEntry API
- Add save directory picker using File System Access API (showDirectoryPicker)
- Process videos sequentially with per-file progress and status tracking
- Add right-side result list with click-to-compare functionality
- Add per-video duration and total batch duration display
- Add retry button for failed items with error detail display
- Remove auto-play on comparison viewer load
- Fix worker error handling: handle "error" command to reject stale promises
- Fix event listener accumulation in video comparison (AbortController)
- Fix XSS risk by escaping HTML in all innerHTML injections
- Fix URL revocation timing in download to prevent large file truncation
- Extract writeToSaveDirectory and truncateName helpers to reduce duplication
- Add Usage Guide panel explaining single/multiple/folder upload options

Files changed:
  docs/upscaler/index.html  (+1110/-181)
  docs/upscaler/upscaler.js (+110)

* fix: prevent auto-play and resource consumption during upscaling

- Set preload="metadata" on preview and comparison video elements
- Explicitly pause preview video after setting src in showVideoPreview
- Remove preview video seek sync from batch processing progress callbacks
  (was causing continuous decode during upscaling, wasting GPU resources)
- Remove preview video seek sync from retry progress callback
- All videos now require manual play; no background resource usage

* fix: improve upscaled video quality with higher bitrate and codec support

- Raise base bitrate from 2.5 Mbps (25e5) to 8 Mbps (8e6) for standard and
  firefox processors, preventing quality loss when source videos have high
  bitrates (e.g. 720p @ 16.7 Mbps was producing 1440p @ 10 Mbps, smaller
  than the original file)
- Double the bitrate for mediabunny processor (X.n1 * 2) to account for the
  4x pixel increase from 2x upscaling
- Add H.264 Level 5.1 (avc1.640033) and Level 5.2 (avc1.640034) codecs to
  the fallback lists, since Level 4.0 (avc1.640028, ~24.6 Mbps) cannot
  support the higher bitrates for 1440p+ outputs
- Add latencyMode: "quality" to VideoEncoder configs for both standard and
  firefox processors, prioritizing encoding quality over latency (suitable
  for offline processing)

* feat: add video data comparison panel for original vs upscaled metrics

- Add a comparison data table below the file info bar showing 6 metrics:
  Resolution, File Size, Duration, Est. Bitrate, Pixels, Process Time
- Display per-metric change percentage with color-coded indicators:
  green (↑) for improvements, red (↓) for regressions, gray for neutral
- Estimated bitrate calculated from file size × 8 / video duration
- Table renders after both original and upscaled video metadata loads
- Auto-hide panel on reset

* fix: make video data comparison panel full-width and responsive

- Move comparison data table from inside the left column to the full-width
  area below the left/right layout, so it is no longer constrained by the
  comparison viewer column width
- Remove table-fixed colgroup and overflow-x-auto that caused horizontal
  scrolling on smaller screens
- Table now uses w-full auto-layout, displaying all 4 columns (Metric,
  Original, Upscaled, Change) without requiring horizontal scrolling

---------

Co-authored-by: rionzhao <rionzhao@tencent.com>

assets/ts/artplayer-plugin-danmuku.d.ts

@@ -0,0 +1,259 @@
+export type Mode = 0 | 1 | 2
+export type Danmuku
+  = | Danmu[]
+    | string // URL
+    | (() => Promise<Danmu[]>)
+    | Promise<Danmu[]>
+
+export interface Slider {
+  min?: number
+  max?: number
+  steps?: {
+    name?: string
+    value?: number | string
+    show?: boolean
+  }[]
+}
+
+export interface Danmu {
+  /**
+   * 弹幕文本
+   */
+  text: string
+
+  /**
+   * 弹幕发送模式: 0: 滚动，1: 顶部，2: 底部
+   */
+  mode?: Mode
+
+  /**
+   * 弹幕颜色
+   */
+  color?: string
+
+  /**
+   * 弹幕出现的时间，单位为秒
+   */
+  time?: number
+
+  /**
+   * 弹幕是否有描边, 默认为 false
+   */
+  border?: boolean
+
+  /**
+   * 弹幕自定义样式
+   */
+  style?: Partial<CSSStyleDeclaration>
+}
+
+export interface Option {
+  /**
+   * 弹幕数据: 函数，数组，Promise，URL
+   */
+  danmuku: Danmuku
+
+  /**
+   * 弹幕持续时间，范围在[1 ~ 10]
+   */
+  speed?: number
+
+  /**
+   * 弹幕上下边距，支持像素数字和百分比
+   */
+  margin?: [number | `${number}%`, number | `${number}%`]
+
+  /**
+   * 弹幕透明度，范围在[0 ~ 1]
+   */
+  opacity?: number
+
+  /**
+   * 默认弹幕颜色，可以被单独弹幕项覆盖
+   */
+  color?: string
+
+  /**
+   * 弹幕模式: 0: 滚动，1: 顶部，2: 底部
+   */
+  mode?: Mode
+
+  /**
+   * 弹幕可见的模式
+   */
+  modes?: Mode[]
+
+  /**
+   * 弹幕字体大小，支持像素数字和百分比
+   */
+  fontSize?: number | `${number}%`
+
+  /**
+   * 弹幕是否防重叠
+   */
+  antiOverlap?: boolean
+
+  /**
+   * 是否同步播放速度
+   */
+  synchronousPlayback?: boolean
+
+  /**
+   * 弹幕发射器挂载点, 默认为播放器控制栏中部
+   */
+  mount?: HTMLDivElement | string
+
+  /**
+   * 是否开启弹幕热度图
+   */
+  heatmap?:
+    | boolean
+    | {
+      xMin?: number
+      xMax?: number
+      yMin?: number
+      yMax?: number
+      scale?: number
+      opacity?: number
+      minHeight?: number
+      sampling?: number
+      smoothing?: number
+      flattening?: number
+    }
+
+  /**
+   * 当播放器宽度小于此值时，弹幕发射器置于播放器底部
+   */
+  width?: number
+
+  /**
+   * 热力图数据
+   */
+  points?: { time: number, value: number }[]
+
+  /**
+   * 弹幕载入前的过滤器，只支持返回布尔值
+   */
+  filter?: (danmu: Danmu) => boolean
+
+  /**
+   * 弹幕发送前的过滤器，支持返回 Promise
+   */
+  beforeEmit?: (danmu: Danmu) => boolean | Promise<boolean>
+
+  /**
+   * 弹幕显示前的过滤器，支持返回 Promise
+   */
+  beforeVisible?: (danmu: Danmu) => boolean | Promise<boolean>
+
+  /**
+   * 弹幕是否可见
+   */
+  visible?: boolean
+
+  /**
+   * 是否开启弹幕发射器
+   */
+  emitter?: boolean
+
+  /**
+   * 弹幕输入框最大长度, 范围在[1 ~ 1000]
+   */
+  maxLength?: number
+
+  /**
+   * 输入框锁定时间，范围在[1 ~ 60]
+   */
+  lockTime?: number
+
+  /**
+   * 弹幕主题，只在自定义挂载时生效
+   */
+  theme?: 'light' | 'dark'
+
+  /**
+   * 不透明度配置项
+   */
+  OPACITY?: Slider
+
+  /**
+   * 弹幕速度配置项
+   */
+  SPEED?: Slider
+
+  /**
+   * 显示区域配置项
+   */
+  MARGIN?: Slider
+
+  /**
+   * 弹幕字号配置项
+   */
+  FONT_SIZE?: Slider
+
+  /**
+   * 颜色列表配置项
+   */
+  COLOR?: string[]
+}
+
+export interface Result {
+  name: 'artplayerPluginDanmuku'
+
+  /**
+   * 发送一条实时弹幕
+   */
+  emit: (danmu: Danmu) => Result
+
+  /**
+   * 重载弹幕源，或者切换新弹幕
+   */
+  load: (danmuku?: Danmuku) => Promise<Result>
+
+  /**
+   * 实时改变弹幕配置
+   */
+  config: (option: Option) => Result
+
+  /**
+   * 隐藏弹幕层
+   */
+  hide: () => Result
+
+  /**
+   * 显示弹幕层
+   */
+  show: () => Result
+
+  /**
+   * 挂载弹幕输入框
+   */
+  mount: (el?: HTMLDivElement | string) => void
+
+  /**
+   * 重置弹幕
+   */
+  reset: () => Result
+
+  /**
+   * 弹幕配置
+   */
+  option: Option
+
+  /**
+   * 是否隐藏弹幕层
+   */
+  isHide: boolean
+
+  /**
+   * 是否弹幕层停止状态
+   */
+  isStop: boolean
+}
+
+declare const artplayerPluginDanmuku: (option: Option) => (art: Artplayer) => Result
+
+export default artplayerPluginDanmuku
+
+export = artplayerPluginDanmuku
+export as namespace artplayerPluginDanmuku;