支持 ASS 字幕原样渲染与字幕显示设置

2026-10-02 12:26:36 +08:00 · 2026-09-11 19:35:08 +08:00
parent e840cbd2c9
commit 0f06bdf929
19 changed files with 874 additions and 76 deletions
@@ -0,0 +1,94 @@
+export type SubtitleCueAlignment = 'start' | 'center' | 'end' | 'left' | 'right'
+export type SubtitleCueVertical = 'rl' | 'lr'
+export type SubtitleCuePositionAlignment = SubtitleCueAlignment | 'line-left' | 'line-right' | 'auto'
+
+export type SubtitleCueSettings = {
+  align?: SubtitleCueAlignment
+  line?: string
+  lineAlign?: SubtitleCueAlignment
+  position?: number
+  positionAlign?: SubtitleCuePositionAlignment
+  size?: number
+  vertical?: SubtitleCueVertical
+}
+
+export type SubtitleCue = {
+  startTime: number
+  endTime: number
+  text: string
+  settings: SubtitleCueSettings
+}
+
+function parseVTTTimestamp(value: string): number {
+  const parts = value.trim().replace(',', '.').split(':')
+  if (parts.length !== 2 && parts.length !== 3) return Number.NaN
+  const seconds = Number(parts.pop())
+  const minutes = Number(parts.pop())
+  const hours = parts.length > 0 ? Number(parts.pop()) : 0
+  if (![hours, minutes, seconds].every(Number.isFinite)) return Number.NaN
+  return hours * 3600 + minutes * 60 + seconds
+}
+
+function parseCueSettings(tokens: string[]): SubtitleCueSettings {
+  const settings: SubtitleCueSettings = {}
+  for (const token of tokens) {
+    const colon = token.indexOf(':')
+    if (colon <= 0) continue
+    const key = token.slice(0, colon).toLowerCase()
+    const value = token.slice(colon + 1)
+    if (key === 'align') {
+      if (['start', 'center', 'end', 'left', 'right'].includes(value)) {
+        settings.align = value as SubtitleCueAlignment
+      }
+    } else if (key === 'line') {
+      settings.line = value
+    } else if (key === 'linealign') {
+      if (['start', 'center', 'end'].includes(value)) {
+        settings.lineAlign = value as SubtitleCueAlignment
+      }
+    } else if (key === 'position') {
+      const position = Number.parseFloat(value)
+      if (Number.isFinite(position)) settings.position = Math.min(100, Math.max(0, position))
+    } else if (key === 'positionalign') {
+      if (['start', 'center', 'end', 'line-left', 'line-right', 'auto'].includes(value)) {
+        settings.positionAlign = value as SubtitleCuePositionAlignment
+      }
+    } else if (key === 'size') {
+      const size = Number.parseFloat(value)
+      if (Number.isFinite(size)) settings.size = Math.min(100, Math.max(0, size))
+    } else if (key === 'vertical') {
+      if (value === 'rl' || value === 'lr') settings.vertical = value
+    }
+  }
+  return settings
+}
+
+export function parseWebVTTCues(body: string): SubtitleCue[] {
+  const blocks = body
+    .replace(/^\uFEFF/, '')
+    .replace(/\r\n?/g, '\n')
+    .split(/\n{2,}/)
+  const cues: SubtitleCue[] = []
+
+  for (const block of blocks) {
+    const lines = block.split('\n')
+    const timingIndex = lines.findIndex((line) => line.includes('-->'))
+    if (timingIndex < 0) continue
+
+    const [rawStart, rawRest] = lines[timingIndex].split('-->', 2)
+    const rest = rawRest.trim().split(/\s+/)
+    const startTime = parseVTTTimestamp(rawStart)
+    const endTime = parseVTTTimestamp(rest[0] || '')
+    const text = lines.slice(timingIndex + 1).join('\n').trim()
+    if (Number.isFinite(startTime) && Number.isFinite(endTime) && endTime >= startTime && text) {
+      cues.push({
+        startTime,
+        endTime,
+        text,
+        settings: parseCueSettings(rest.slice(1)),
+      })
+    }
+  }
+
+  return cues
+}