fix(ai-avatar): 端到端一致性修复（标题/封面/B-roll位置/B-roll时长）

修复5个问题：

1. 最终视频标题一致性
   - 后端 drawtext 默认 font_size 从 36 改为 28（对齐前端 DEFAULT_TITLE_CONFIG.size）
   - 后端 drawtext 默认 position 从 'top' 改为 'bottom'（对齐前端默认值）
   - 前端 contract.ts font_size fallback 从 36 改为 28

2. 封面与视频一致性
   - 渲染完成后自动用 output_cover_url 更新前端封面配置
   - 前端封面标题预览 fontSize 改用 size*0.55 缩放（与对口型预览对齐）
   - 封面默认阴影改为 none（与后端 drawtext 无 shadow 行为对齐）

3. B-roll 位置一致性
   - ModalBRollEditor 使用 lipsyncJob.script_text（TTS 时锁定的文案）
     而非 state.scriptText（用户可能已修改的文案）

4. B-roll 时长精确化
   - 后端 lipsync_tts.py 新增 _compute_sentence_timings()：
     TTS 音频用 ffmpeg silencedetect 检测静音点，与句子边界对齐
   - 新增 sentence_timings JSON 字段到 LipsyncJobModel + Alembic migration
   - 前端 sentences.ts 不再做字数比例估算，改为接收后端精确时间戳
   - ModalBRollEditor 接收 sentenceTimings prop

5. 标题拖拽位置修复
   - PanelLipsyncPreview 拖拽标题发送百分比坐标(0-100) + position:'custom'
   - 后端 build_title_drawtext_filter 的 custom 位置改用 drawtext 表达式
     x=(w-text_w)*{pct_x} y=(h-text_h)*{pct_y}（百分比，与视频尺寸解耦）

文件变更：
- apps/api/app/tasks/lipsync_tts.py: 句子时间戳计算
- apps/api/app/schemas/lipsync.py: sentence_timings 字段
- packages/adapters/sqlalchemy_impl/models.py: sentence_timings 列
- packages/domain/video_filter_builder.py: 百分比坐标 + 默认值对齐
- alembic/versions/075_add_sentence_timings.py: 数据库迁移
- apps/web/src/pages/ai-avatar/types.ts: SentenceTiming + RenderJob.output_cover_url
- apps/web/src/pages/ai-avatar/utils/sentences.ts: 移除字数估算
- apps/web/src/pages/ai-avatar/utils/contract.ts: font_size 默认值
- apps/web/src/pages/ai-avatar/components/PanelLipsyncPreview.tsx: 拖拽百分比
- apps/web/src/pages/ai-avatar/components/PanelCoverAndGenerate.tsx: 标题缩放
- apps/web/src/pages/ai-avatar/components/ModalBRollEditor.tsx: 后端时间戳
- apps/web/src/pages/ai-avatar/AiAvatarPage.tsx: 封面更新 + 传参
- tests/unit/test_video_filter_builder.py: 测试更新

alembic/versions/075_add_sentence_timings.py

@@ -0,0 +1,27 @@
+"""add sentence_timings to lipsync_jobs
+
+Revision ID: 075_add_sentence_timings
+Revises: 074_ai_avatar_render_script_id_optional
+Create Date: 2026-09-12
+"""
+
+import sqlalchemy as sa
+
+from alembic import op
+
+revision = "075_add_sentence_timings"
+down_revision = "074_ai_avatar_render_script_id_optional"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    with op.batch_alter_table("lipsync_jobs") as batch:
+        batch.add_column(
+            sa.Column("sentence_timings", sa.JSON(), nullable=True),
+        )
+
+
+def downgrade() -> None:
+    with op.batch_alter_table("lipsync_jobs") as batch:
+        batch.drop_column("sentence_timings")

apps/api/app/schemas/lipsync.py

@@ -33,6 +33,7 @@ class LipsyncJobResponse(BaseModel):
     output_duration: float
     error_message: str
     error_code: str
+    sentence_timings: Optional[list] = None
     submitted_at: Optional[datetime] = None
     completed_at: Optional[datetime] = None
     created_at: datetime

apps/api/app/tasks/lipsync_tts.py

@@ -54,6 +54,149 @@ def _sign_media_url(url: str) -> str:
         return url
 
 
+
+
+def _split_script_into_sentences(script_text: str) -> list[str]:
+    """按句号/问号/感叹号/分号/换行分句（与前端 splitScriptIntoSentences 一致）."""
+    import re
+    text = (script_text or "").strip()
+    if not text:
+        return []
+    parts = re.split(r"[。！？!?；;\n\r]+", text)
+    return [p.strip() for p in parts if p.strip()]
+
+
+def _compute_sentence_timings(audio_data: bytes, script_text: str, total_duration: float) -> list[dict]:
+    """基于 TTS 音频的静音检测，精确计算每句文案的起止时间.
+
+    使用 ffmpeg silencedetect 检测静音段，将静音点与句子边界对齐。
+    比字数比例估算准确得多。
+
+    Args:
+        audio_data: TTS 音频二进制数据（MP3）
+        script_text: 文案全文
+        total_duration: 音频总时长（秒）
+
+    Returns:
+        list[{"index": int, "text": str, "start_time": float, "end_time": float}]
+    """
+    import re
+    import subprocess
+    import tempfile
+
+    sentences = _split_script_into_sentences(script_text)
+    if not sentences:
+        return []
+
+    # 写入临时音频文件
+    with tempfile.NamedTemporaryFile(suffix=".mp3", delete=False) as tmp:
+        tmp.write(audio_data)
+        tmp_path = tmp.name
+
+    try:
+        # 用 ffmpeg silencedetect 检测静音段
+        result = subprocess.run(
+            [
+                "ffmpeg", "-i", tmp_path,
+                "-af", "silencedetect=noise=-25dB:d=0.3",
+                "-f", "null", "-",
+            ],
+            capture_output=True,
+            text=True,
+            timeout=30,
+        )
+        stderr = result.stderr or ""
+
+        # 解析静音结束时间点（silence_end: X.XXX）
+        silence_ends = []
+        for match in re.finditer(r"silence_end:\s*([\d.]+)", stderr):
+            t = float(match.group(1))
+            if 0 < t < total_duration:
+                silence_ends.append(t)
+
+        # 如果没有检测到足够的静音点，降级为字数比例估算
+        if len(silence_ends) < len(sentences) - 1:
+            logger.warning(
+                "[sentence_timings] 静音点不足(%d < %d)，降级为字数比例估算",
+                len(silence_ends), len(sentences) - 1,
+            )
+            return _estimate_sentence_timings_by_chars(sentences, total_duration)
+
+        # 贪心匹配：N-1 个句子边界对应 N-1 个静音点
+        # 按时间均匀分布期望值，选择最近的静音点
+        n_boundaries = len(sentences) - 1
+        boundaries = []
+        used_indices = set()
+
+        for i in range(n_boundaries):
+            # 期望的边界位置（按句子数量均匀分布）
+            expected_pos = (i + 1) / len(sentences) * total_duration
+            # 找最近的未使用静音点
+            best_idx = None
+            best_dist = float("inf")
+            for j, t in enumerate(silence_ends):
+                if j in used_indices:
+                    continue
+                dist = abs(t - expected_pos)
+                if dist < best_dist:
+                    best_dist = dist
+                    best_idx = j
+            if best_idx is not None:
+                used_indices.add(best_idx)
+                boundaries.append(silence_ends[best_idx])
+
+        boundaries.sort()
+
+        # 构建 sentence_timings
+        timings = []
+        prev_end = 0.0
+        for i, sent in enumerate(sentences):
+            start = prev_end
+            end = boundaries[i] if i < len(boundaries) else total_duration
+            timings.append({
+                "index": i,
+                "text": sent,
+                "start_time": round(start, 2),
+                "end_time": round(end, 2),
+            })
+            prev_end = end
+
+        return timings
+
+    except Exception as exc:
+        logger.warning("[sentence_timings] 静音检测异常，降级为字数比例估算: %s", exc)
+        return _estimate_sentence_timings_by_chars(sentences, total_duration)
+    finally:
+        import os
+        try:
+            os.unlink(tmp_path)
+        except Exception:
+            pass
+
+
+def _estimate_sentence_timings_by_chars(sentences: list[str], total_duration: float) -> list[dict]:
+    """降级方案：按字数比例估算句子时间（与原前端逻辑一致）."""
+    if not sentences or total_duration <= 0:
+        return []
+    total_chars = sum(len(s.replace("\s", "")) for s in sentences)
+    if total_chars == 0:
+        return []
+
+    timings = []
+    acc = 0
+    for i, sent in enumerate(sentences):
+        chars = len(sent.replace("\s", ""))
+        start = (acc / total_chars) * total_duration
+        end = ((acc + chars) / total_chars) * total_duration
+        timings.append({
+            "index": i,
+            "text": sent,
+            "start_time": round(start, 2),
+            "end_time": round(end, 2),
+        })
+        acc += chars
+    return timings
+
 @shared_task(
     bind=True,
     name="lipsync_tts.synthesize_and_submit",
@@ -179,6 +322,50 @@ def tts_synthesize_and_submit(
 
         db.commit()
 
+        # 2.5 计算精确句子时间戳（基于 TTS 音频静音检测）
+        import os as _os
+        _st_tmp_path = None
+        try:
+            import subprocess as _sp
+            import tempfile as _tmpf
+
+            # 下载音频用于探测时长和静音检测
+            if isinstance(job.audio_url, str) and job.audio_url:
+                from packages.shared.url_security import safe_download_bytes as _sdl
+                _audio_bytes = _sdl(job.audio_url, purpose="sentence_timings", timeout=30.0)
+            else:
+                _audio_bytes = audio_data
+
+            # ffprobe 获取音频时长
+            with _tmpf.NamedTemporaryFile(suffix=".mp3", delete=False) as _atmp:
+                _atmp.write(_audio_bytes)
+                _st_tmp_path = _atmp.name
+
+            _probe_result = _sp.run(
+                ["ffprobe", "-v", "error", "-show_entries", "format=duration",
+                 "-of", "default=noprint_wrappers=1:nokey=1", _st_tmp_path],
+                capture_output=True, text=True, timeout=10,
+            )
+            _audio_duration = float(_probe_result.stdout.strip()) if _probe_result.stdout.strip() else 0.0
+
+            if _audio_duration > 0:
+                _timings = _compute_sentence_timings(_audio_bytes, script_text, _audio_duration)
+                if _timings:
+                    job.sentence_timings = _timings
+                    logger.info(
+                        "[lipsync_tts] 句子时间戳已计算: job_id=%s sentences=%d duration=%.1f",
+                        job_id, len(_timings), _audio_duration,
+                    )
+            db.commit()
+        except Exception as _st_err:
+            logger.warning("[lipsync_tts] 句子时间戳计算失败（不影响主流程）: job_id=%s err=%s", job_id, _st_err)
+        finally:
+            if _st_tmp_path:
+                try:
+                    _os.unlink(_st_tmp_path)
+                except Exception:
+                    pass
+
         # 3. 签名 URL 并提交到 MediaKit（复用模块内 _sign_media_url，避免对 LipsyncService 的耦合）
         audio_url = _sign_media_url(job.audio_url)
         video_url = _sign_media_url(job.video_url)

apps/web/src/pages/ai-avatar/AiAvatarPage.tsx

@@ -241,6 +241,15 @@ const AiAvatarPage: React.FC = () => {
             if (renderTimerRef.current) clearInterval(renderTimerRef.current)
             renderTimerRef.current = null
             setRenderStatus("completed")
+            // 渲染完成后，用最终视频的封面更新前端封面配置
+            if (updated.output_cover_url) {
+              state.setCoverConfig((prev) => ({
+                ...prev,
+                mode: "auto_frame",
+                smart_cover_url: updated.output_cover_url,
+                thumbnail_url: updated.output_cover_url,
+              }))
+            }
             message.success("视频已生成并保存到成片库")
           } else if (updated.status === "failed") {
             if (renderTimerRef.current) clearInterval(renderTimerRef.current)
@@ -488,8 +497,9 @@ const AiAvatarPage: React.FC = () => {
           open={state.showBRollModal}
           onClose={() => state.setShowBRollModal(false)}
           existingSegments={state.bRollSegments}
-          scriptText={state.scriptText}
+          scriptText={state.lipsyncJob?.script_text || state.scriptText}
           outputDuration={state.lipsyncJob?.output_duration ?? 0}
+          sentenceTimings={state.lipsyncJob?.sentence_timings}
           onConfirm={state.addBRollSegment}
           onRemove={state.removeBRollSegment}
         />

apps/web/src/pages/ai-avatar/components/ModalBRollEditor.tsx

@@ -5,12 +5,12 @@
  * - 左侧：先选素材库（video 库）→ 再选该库视频素材（已被其他 segment 使用的素材
  *   标灰 + "已选择" 遮罩，pointer-events:none 防重复选择）
  * - 右侧：文案句子列表（点选对应段落，替代原数字索引框）/ 全屏 or 画中画 / 四角位置+大小
- *   （开始/结束时间已删除，按句子字数占比 × 口播总时长自动估算）
+ *   （开始/结束时间来自后端精确句子时间戳，基于 TTS 音频静音检测）
  * - 底部：已配置的画面插入列表（可删除）
  */
 import React, { useEffect, useMemo, useState } from "react"
 import { getAssets, getAssetLibraries, type AssetItem, type AssetLibraryItem } from "@/api/assets"
-import type { BRollSegment, BRollInsertMode, PipPosition } from "../types"
+import type { BRollSegment, BRollInsertMode, PipPosition, SentenceTiming } from "../types"
 import { splitScriptIntoSentences, type ScriptSentence } from "../utils/sentences"
 
 interface ModalBRollEditorProps {
@@ -18,10 +18,12 @@ interface ModalBRollEditorProps {
   onClose: () => void
   /** 当前已有的 B-roll segments（用于标灰已选素材） */
   existingSegments: BRollSegment[]
-  /** 当前文案全文（用于分句） */
+  /** 文案全文（优先使用对口型时锁定的 scriptText） */
   scriptText: string
-  /** 对口型成片总时长（秒），用于时间自动估算 */
+  /** 对口型成片总时长（秒） */
   outputDuration: number
+  /** 后端精确句子时间戳（来自 lipsyncJob.sentence_timings） */
+  sentenceTimings?: SentenceTiming[] | null
   onConfirm: (segment: BRollSegment) => void
   onRemove: (id: string) => void
 }
@@ -44,6 +46,7 @@ const ModalBRollEditor: React.FC<ModalBRollEditorProps> = ({
   existingSegments,
   scriptText,
   outputDuration,
+  sentenceTimings,
   onConfirm,
   onRemove,
 }) => {
@@ -62,10 +65,10 @@ const ModalBRollEditor: React.FC<ModalBRollEditorProps> = ({
   const [pipPosition, setPipPosition] = useState<PipPosition>("top-right")
   const [pipScale, setPipScale] = useState(0.3)
 
-  /** 文案分句（⑤） */
+  /** 文案分句（使用后端精确时间戳） */
   const sentences = useMemo(
-    () => splitScriptIntoSentences(scriptText, outputDuration),
-    [scriptText, outputDuration],
+    () => splitScriptIntoSentences(scriptText, sentenceTimings),
+    [scriptText, sentenceTimings],
   )
 
   /** 已被现有 segments 占用的素材 id 集合（标灰、禁止重复选择） */
@@ -264,7 +267,7 @@ const ModalBRollEditor: React.FC<ModalBRollEditorProps> = ({
                           >
                             <span className="aa-sentence-item__idx">{sent.index + 1}</span>
                             <span className="aa-sentence-item__text">{sent.text}</span>
-                            {outputDuration > 0 && (
+                            {sent.endTime > 0 && (
                               <span className="aa-sentence-item__time">
                                 {sent.startTime.toFixed(1)}-{sent.endTime.toFixed(1)}s
                               </span>
@@ -349,7 +352,7 @@ const ModalBRollEditor: React.FC<ModalBRollEditorProps> = ({
                           selectedSentence.endTime,
                           selectedSentence.startTime + 0.5,
                         ).toFixed(1)}
-                        s （按字数自动估算）
+                        s
                       </div>
                     </>
                   ) : (

apps/web/src/pages/ai-avatar/components/PanelCoverAndGenerate.tsx

@@ -120,7 +120,7 @@ const PanelCoverAndGenerate: React.FC<PanelCoverAndGenerateProps> = ({
       wordBreak: "break-word",
       whiteSpace: "pre-wrap",
       color: titleConfig.color || "#ffffff",
-      fontSize: `${titleConfig.size}px`,
+      fontSize: `${(titleConfig.size || 28) * 0.55}px`, // 预览容器缩放，与 PanelLipsyncPreview 对齐
       fontFamily: getFontFamily(titleConfig.font),
       fontWeight: titleConfig.bold ? "bold" : "normal",
       fontStyle: titleConfig.italic ? "italic" : "normal",
@@ -153,8 +153,8 @@ const PanelCoverAndGenerate: React.FC<PanelCoverAndGenerateProps> = ({
     } else if (titleConfig.shadow) {
       style.textShadow = "0 2px 8px rgba(0,0,0,0.7), 0 0 2px rgba(0,0,0,0.5)"
     } else {
-      // 默认给轻微阴影保证白字在亮背景可读
-      style.textShadow = "0 2px 6px rgba(0,0,0,0.6)"
+      // 无描边无阴影时，不加额外效果（与后端 drawtext 对齐：无 stroke/shadow 则不加）
+      style.textShadow = "none"
     }
 
     return style

apps/web/src/pages/ai-avatar/components/PanelLipsyncPreview.tsx

@@ -14,8 +14,8 @@ interface PanelLipsyncPreviewProps {
   onRemoveBRoll: (id: string) => void
   /** 标题配置（实时叠加预览用） */
   titleConfig?: AiAvatarTitleConfig
-  /** 标题位置变更回调（拖拽结束时调用） */
-  onTitlePositionChange?: (pos: { pos_x: number; pos_y: number }) => void
+  /** 标题位置变更回调（拖拽结束时调用，发送百分比坐标 + position:"custom"） */
+  onTitlePositionChange?: (pos: { pos_x: number; pos_y: number; position: string }) => void
 }
 
 const BROLL_MODE_LABEL: Record<BRollSegment["mode"], string> = {
@@ -68,11 +68,13 @@ export function PanelLipsyncPreview({
         padding: "4px 8px",
         textShadow: titleConfig.shadow ? "0 2px 4px rgba(0,0,0,0.8)" : undefined,
         WebkitTextStroke: titleConfig.stroke ? "1.5px #000" : undefined,
-        ...(titleConfig.position === "top"
-          ? { top: 8 }
-          : titleConfig.position === "bottom"
-            ? { bottom: 8 }
-            : { top: "50%", transform: "translateX(-50%) translateY(-50%)" }),
+        ...(titleConfig.position === "custom" && titleConfig.pos_x != null && titleConfig.pos_y != null
+          ? { left: `${titleConfig.pos_x}%`, top: `${titleConfig.pos_y}%`, transform: "translateX(-50%) translateY(-50%)" }
+          : titleConfig.position === "top"
+            ? { top: 8 }
+            : titleConfig.position === "bottom"
+              ? { bottom: 8 }
+              : { top: "50%", transform: "translateX(-50%) translateY(-50%)" }),
       }
     : null
 
@@ -105,7 +107,10 @@ export function PanelLipsyncPreview({
       const rect = previewContainerRef.current.getBoundingClientRect()
       const relX = Math.max(0, Math.min(rect.width, e.clientX - rect.left))
       const relY = Math.max(0, Math.min(rect.height, e.clientY - rect.top))
-      onTitlePositionChange({ pos_x: relX, pos_y: relY })
+      // 发送百分比坐标（0-100），与后端 drawtext 百分比表达式对齐
+      const xpct = Math.round((relX / rect.width) * 1000) / 10
+      const ypct = Math.round((relY / rect.height) * 1000) / 10
+      onTitlePositionChange({ pos_x: xpct, pos_y: ypct, position: "custom" })
     }
     ;(e.currentTarget as HTMLDivElement).style.cursor = "grab"
   }

apps/web/src/pages/ai-avatar/types.ts

@@ -44,12 +44,22 @@ export interface LipsyncJob {
   status: LipsyncStatus
   progress: number
   output_video_url: string | null
-  /** 对口型成片总时长（秒），后端返回；用于 B-roll 时间自动估算（#1809 ⑥） */
+  /** 对口型成片总时长（秒），后端返回 */
   output_duration?: number
+  /** 精确句子时间戳（后端基于 TTS 音频静音检测计算） */
+  sentence_timings?: SentenceTiming[] | null
   error_message: string | null
   created_at: string
 }
 
+/* ── 句子时间戳（后端精确计算） ── */
+export interface SentenceTiming {
+  index: number
+  text: string
+  start_time: number
+  end_time: number
+}
+
 /* ── B-roll 画面插入 ── */
 export type BRollInsertMode = "fullscreen" | "pip"
 export type PipPosition = "top-left" | "top-right" | "bottom-left" | "bottom-right"
@@ -77,7 +87,7 @@ export interface AiAvatarTitleConfig {
   shadow: boolean
   color: string
   auto_subtitle: boolean
-  /** 自定义位置坐标（position=custom 时生效，像素） */
+  /** 自定义位置坐标（position=custom 时生效，百分比 0-100） */
   pos_x?: number
   pos_y?: number
 }
@@ -101,6 +111,7 @@ export interface RenderJob {
   status: RenderStatus
   progress: number
   output_video_url: string | null
+  output_cover_url: string | null
   error_message: string | null
   created_at: string
 }

apps/web/src/pages/ai-avatar/utils/contract.ts

@@ -39,7 +39,7 @@ export function buildTitleConfigPayload(cfg: AiAvatarTitleConfig): Record<string
     text,
     enabled: true,
     font: cfg.font || "思源黑体",
-    font_size: Math.round(cfg.size) || 36,
+    font_size: Math.round(cfg.size) || 28,
     font_color: cfg.color || "#ffffff",
     position,
     bold: !!cfg.bold,

apps/web/src/pages/ai-avatar/utils/sentences.ts

@@ -1,6 +1,10 @@
 /**
- * AI数字人 — 文案分句 & B-roll 时间自动估算（#1809 ⑤⑥）
+ * AI数字人 — 文案分句工具
+ *
+ * 分句规则与后端 _split_script_into_sentences 保持一致。
+ * 时间戳由后端基于 TTS 音频静音检测精确计算，前端不再做字数比例估算。
  */
+import type { SentenceTiming } from "../types"
 
 export interface ScriptSentence {
   /** 句子序号（从 0 开始，对应提交给后端的 script_segment_index） */
@@ -9,21 +13,21 @@ export interface ScriptSentence {
   text: string
   /** 句子字数（按中文/字符计，去除空白） */
   charCount: number
-  /** 累计起始字数（用于时间估算） */
+  /** 累计起始字数 */
   startChar: number
-  /** 估算的对口型视频内起始时间（秒） */
+  /** 精确起始时间（秒），来自后端 sentence_timings；无数据时为 0 */
   startTime: number
-  /** 估算的对口型视频内结束时间（秒） */
+  /** 精确结束时间（秒），来自后端 sentence_timings；无数据时为 0 */
   endTime: number
 }
 
 /**
  * 按句号/问号/感叹号/分号/换行分句（兼容中英文标点）。
- * 空文案返回空数组。时间按「该句字数 ÷ 全文总字数 × 口播总时长」线性估算。
+ * 时间戳从后端 sentence_timings 获取（精确）；若无则返回 0（由调用方降级处理）。
  */
 export function splitScriptIntoSentences(
   scriptText: string,
-  outputDuration: number,
+  sentenceTimings?: SentenceTiming[] | null,
 ): ScriptSentence[] {
   const text = (scriptText || "").trim()
   if (!text) return []
@@ -33,30 +37,25 @@ export function splitScriptIntoSentences(
     .map((part) => part.trim())
     .filter((part) => part.length > 0)
 
-  const totalChars = rawParts.reduce((sum, part) => sum + part.replace(/\s/g, "").length, 0)
-  const duration = outputDuration > 0 ? outputDuration : 0
-
   const sentences: ScriptSentence[] = []
   let accChar = 0
   rawParts.forEach((part, i) => {
     const charCount = part.replace(/\s/g, "").length
-    const startTime = duration > 0 && totalChars > 0 ? (accChar / totalChars) * duration : 0
-    const endTime =
-      duration > 0 && totalChars > 0 ? ((accChar + charCount) / totalChars) * duration : 0
+    // 从后端精确时间戳获取；无数据时返回 0
+    const timing = sentenceTimings?.[i]
+    const startTime = timing?.start_time ?? 0
+    const endTime = timing?.end_time ?? 0
+
     sentences.push({
       index: i,
       text: part,
       charCount,
       startChar: accChar,
-      startTime: round1(startTime),
-      endTime: round1(endTime),
+      startTime,
+      endTime,
     })
     accChar += charCount
   })
 
   return sentences
 }
-
-function round1(n: number): number {
-  return Math.round(n * 10) / 10
-}

packages/adapters/sqlalchemy_impl/models.py

@@ -703,6 +703,9 @@ class LipsyncJobModel(Base):
     error_message = Column(Text, nullable=False, default="")
     error_code = Column(String(100), nullable=False, default="")
 
+    # 精确句子时间戳（TTS 合成后由 silencedetect 计算，用于 B-roll 精确定位）
+    sentence_timings = Column(JSON, nullable=True)  # list[{index,text,start_time,end_time}]
+
     # 时间戳
     submitted_at = Column(DateTime, nullable=True)
     completed_at = Column(DateTime, nullable=True)

packages/domain/video_filter_builder.py

@@ -481,13 +481,13 @@ def build_title_drawtext_filter(
 
     # ── 样式参数 ──
     font_name = title_config.get("font") or title_config.get("font_preset") or "思源黑体"
-    font_size = int(title_config.get("font_size") or title_config.get("size") or 36)
+    font_size = int(title_config.get("font_size") or title_config.get("size") or 28)
     font_color = title_config.get("font_color") or title_config.get("color") or "#ffffff"
     # 去掉 # 前缀（drawtext 用纯 hex 或颜色名）
     if font_color.startswith("#"):
         font_color = font_color[1:]
 
-    position = title_config.get("position", "top")
+    position = title_config.get("position") or "bottom"
     bold = bool(title_config.get("bold", True))
     stroke = title_config.get("stroke")
     shadow = title_config.get("shadow")
@@ -556,8 +556,13 @@ def build_title_drawtext_filter(
         and not isinstance(pos_x, bool)
         and not isinstance(pos_y, bool)
     ):
-        params.append(f"x={int(pos_x)}")
-        params.append(f"y={int(pos_y)}")
+        # pos_x/pos_y 为百分比坐标（0-100），转换为 drawtext 表达式
+        # 例如 pos_x=50 → x=(w-text_w)*0.50（水平居中偏50%）
+        #      pos_y=30 → y=(h-text_h)*0.30
+        pct_x = max(0.0, min(100.0, float(pos_x))) / 100.0
+        pct_y = max(0.0, min(100.0, float(pos_y))) / 100.0
+        params.append(f"x=(w-text_w)*{pct_x:.4f}")
+        params.append(f"y=(h-text_h)*{pct_y:.4f}")
     else:
         # 三档预设位置：top / center / bottom
         # x 始终水平居中：(w-text_w)/2

tests/unit/test_video_filter_builder.py

@@ -1065,12 +1065,23 @@ class TestDrawtextPositionBranches(unittest.TestCase):
         self.assertIn("y=h-text_h-50", result)
 
     @patch("packages.domain.video_filter_builder._resolve_font_path")
-    def test_position_custom_with_float_coords(self, mock_font):
+    def test_position_custom_with_percentage_coords(self, mock_font):
+        """自定义位置：百分比坐标转换为 drawtext 表达式."""
+        mock_font.return_value = ""
+        # pos_x=50, pos_y=30 → x=(w-text_w)*0.5000, y=(h-text_h)*0.3000
+        result = build_title_drawtext_filter({"text": "标题", "position": "custom", "pos_x": 50, "pos_y": 30})
+        self.assertIsNotNone(result)
+        self.assertIn("x=(w-text_w)*0.5000", result)
+        self.assertIn("y=(h-text_h)*0.3000", result)
+
+    @patch("packages.domain.video_filter_builder._resolve_font_path")
+    def test_position_custom_clamped_to_100(self, mock_font):
+        """自定义位置：超过100的坐标被截断到100%."""
         mock_font.return_value = ""
         result = build_title_drawtext_filter({"text": "标题", "position": "custom", "pos_x": 100.7, "pos_y": 200.3})
         self.assertIsNotNone(result)
-        self.assertIn("x=100", result)
-        self.assertIn("y=200", result)
+        self.assertIn("x=(w-text_w)*1.0000", result)
+        self.assertIn("y=(h-text_h)*1.0000", result)
 
     @patch("packages.domain.video_filter_builder._resolve_font_path")
     def test_position_custom_bool_coords_fallback(self, mock_font):