apps/worker/video_processing/gpu_direct_pipeline.py

@@ -26,6 +26,33 @@ DEFAULT_DRAWTEXT_FONT = "Noto Sans CJK SC"
 EDGE_CROP_MIN_PCT = 0.02
 EDGE_CROP_MAX_PCT = 0.05
 
+# 标题/字幕样式基准宽度（px）。前端 TitleSettings 所有长度字段（size/描边/阴影/margin/pos）
+# 均以 720p 为基准（见前端 titleCanvas.ts 注释 scale=videoWidth/720，types.ts "px @720p"），
+# 非 720p 输出时按 video_width / TITLE_SIZE_REF_WIDTH 等比缩放，保证成片位置与前端预览一致。
+TITLE_SIZE_REF_WIDTH = 720
+# 与前端 titleCanvas.ts 对齐：top 时文本 top-edge 距视频顶 = PAD(16@720p) + margin_top(默认 24@720p)
+TITLE_PAD_TOP = 16
+TITLE_DEFAULT_MARGIN_TOP = 24
+TITLE_DEFAULT_MARGIN_BOTTOM = 24
+SUBTITLE_DEFAULT_MARGIN_BOTTOM = 60  # 字幕距底边距（720p 基准，与前端字幕面板默认对齐）
+
+
+def _scale_title_len(value, video_width: int):
+    """将 720p 基准长度按 video_width 等比缩放（与 packages/domain/ass_subtitle_builder._scale_len 一致）。
+
+    int 输入 → 返回 int；float 输入 → 返回 float；非法值原样返回。
+    """
+    if value is None:
+        return None
+    try:
+        v = float(value)
+    except (TypeError, ValueError):
+        return value
+    if not video_width or video_width <= 0:
+        return int(round(v)) if isinstance(value, int) else v
+    scaled = v * (video_width / TITLE_SIZE_REF_WIDTH)
+    return int(round(scaled)) if isinstance(value, int) else scaled
+
 
 def escape_drawtext_text(text: str) -> str:
     if not text:
@@ -91,22 +118,52 @@ def _hex_to_drawtext_color(hex_color: str, default: str = "white") -> str:
     return default
 
 
-def _position_to_drawtext_xy(position: str, *, margin: int = 40) -> tuple[str, str]:
-    """把 top/center/bottom 位置映射到 drawtext x/y 表达式。
+def _position_to_drawtext_xy(
+    position: str,
+    *,
+    margin_top: int = 0,
+    margin_bottom: int = 0,
+    pos_x: Optional[float] = None,
+    pos_y: Optional[float] = None,
+) -> tuple[str, str]:
+    """把位置映射到 drawtext x/y 表达式，对齐前端 titleCanvas.ts 预览坐标。
 
-    返回 (x_expr, y_expr)。默认居中对齐。margin 为距离视频边缘的像素。
+    position 支持: top / center(middle) / bottom / custom。
+    - top: 文本基线放在 margin_top + ascent ≈ 顶部边缘留 PAD+margin_top 距离
+      （drawtext y 是基线位置；为让文本 top-edge ≈ margin_top，把 y 设为 margin_top + font_ascent。
+      但 drawtext 运行时不知道 ascent，用经验系数 0.8*fontsize 近似，和前端 PAD+margin_top 对齐）。
+      为简化且精确对齐，这里用 y=margin_top（基线放在 margin_top 处），
+      并在调用处把 margin_top 设为 前端的 (PAD+marginTop)+ascent 估算值。
+    - center: (h-text_h)/2 垂直居中。
+    - bottom: 文本底线距离底边 margin_bottom。
+    - custom: pos_x/pos_y 为百分比 0-100（前端拖拽坐标系），文本中心落在 (pct_x*w, pct_y*h)。
+    margin_top/margin_bottom 为已按 video_width 缩放过的像素值。
     """
-    p = (position or "bottom").lower().strip()
+    p = (position or "top").lower().strip()
+
+    # custom：自由拖拽百分比坐标（0-100）→ 文本中心对齐到 (pct*w, pct*h)
+    if p == "custom" and pos_x is not None and pos_y is not None:
+        try:
+            px = max(0.0, min(100.0, float(pos_x))) / 100.0
+            py = max(0.0, min(100.0, float(pos_y))) / 100.0
+            return f"(w-text_w)*{px:.4f}", f"(h-text_h)*{py:.4f}"
+        except (TypeError, ValueError):
+            pass  # fall through to default
+
     x = "(w-text_w)/2"
     if p in ("top",):
-        y = f"{margin}"
+        # drawtext y 是 baseline 位置。中文字符顶边距基线约 0.85*fontsize（ascent），
+        # 但 drawtext 表达式里无法引用 fontsize 变量；这里让 y=margin_top 作为 baseline，
+        # 调用方传入的 margin_top 已包含 ascent 补偿，使文本 top-edge 与前端 PAD+marginTop 对齐。
+        y = f"{int(margin_top)}"
     elif p in ("center", "middle"):
         y = "(h-text_h)/2"
     elif p in ("bottom",):
-        y = f"h-th-{margin}"
+        # h-th-margin_bottom：th ≈ text_h，文本底边距底边 margin_bottom
+        y = f"h-th-{int(margin_bottom)}"
     else:
-        # 未知值回退到底部
-        y = f"h-th-{margin}"
+        # 未知值回退到顶部（与前端默认 position=top 对齐）
+        y = f"{int(margin_top)}"
     return x, y
 
 
@@ -118,8 +175,11 @@ def _build_drawtext_filters(
     font: str = DEFAULT_DRAWTEXT_FONT,
     font_size: int = 0,
     font_color: str = "white",
-    position: str = "bottom",
-    margin: int = 40,
+    position: str = "top",
+    margin_top: int = 0,
+    margin_bottom: int = 0,
+    pos_x: Optional[float] = None,
+    pos_y: Optional[float] = None,
     box_enabled: bool = False,
     box_color: str = "black@0.5",
     borderw: int = 0,
@@ -139,7 +199,13 @@ def _build_drawtext_filters(
     if not txt:
         return []
 
-    x_expr, y_expr = _position_to_drawtext_xy(position, margin=margin)
+    x_expr, y_expr = _position_to_drawtext_xy(
+        position,
+        margin_top=margin_top,
+        margin_bottom=margin_bottom,
+        pos_x=pos_x,
+        pos_y=pos_y,
+    )
     fc_color = _hex_to_drawtext_color(font_color, default="white")
     bd_color = _hex_to_drawtext_color(border_color, default="black")
     sh_color = _hex_to_drawtext_color(shadow_color, default="black@0.6")
@@ -427,20 +493,46 @@ def build_direct_render(
 
     # 5. drawtext 字幕（标题 + 静态全文 + ASR 分段）
     # ── 解析 title_config（兼容字段名 font_size/font_color → size/color） ──
+    # 所有长度字段（size/stroke/shadow/margin）均为 720p 基准值，按 video_width 等比缩放，
+    # 对齐前端 titleCanvas.ts（scale=videoWidth/720）与 CPU/ASS 路径 _scale_len 规则，
+    # 保证成片标题位置/大小与前端预览一致（修复 PR#2093 位置不匹配 bug）。
     t_cfg = dict(title_config) if isinstance(title_config, dict) else {}
     t_enabled = bool(t_cfg.get("enabled", True))
     t_text = (t_cfg.get("text", "") or title_text or "").strip()
     t_font = str(t_cfg.get("font", font) or font)
+    # size：前端传 px@720p，未配置默认 28（前端 DEFAULT_TITLE_SETTINGS.size=28，对齐 AI Avatar 默认48）
     t_size_raw = t_cfg.get("size", t_cfg.get("font_size", 0))
     try:
-        t_size = int(t_size_raw) if t_size_raw else 0
+        t_size_720 = int(t_size_raw) if t_size_raw else 0
     except (TypeError, ValueError):
-        t_size = 0
-    if t_size <= 0:
-        t_size = max(int(output_height * 0.05), 24)
+        t_size_720 = 0
+    if t_size_720 <= 0:
+        t_size_720 = 36  # 与 config_schemas 默认 48 接近；AI Avatar 前端默认 48，剪辑前端默认 28，取中
+    t_size = _scale_title_len(t_size_720, output_width)
+    # stroke/shadow 长度字段也需 720p→输出分辨率缩放
     t_color = str(t_cfg.get("color", t_cfg.get("font_color", "#ffffff")))
-    t_position = str(t_cfg.get("position", "bottom")).lower()
-    t_margin = max(40, int(output_height * 0.05))
+    t_position = str(t_cfg.get("position", "top")).lower().strip()
+    # 自由拖拽坐标（百分比 0-100），与 video_filter_builder.build_title_drawtext_filter 一致
+    t_pos_x = t_cfg.get("pos_x")
+    t_pos_y = t_cfg.get("pos_y")
+    try:
+        t_pos_x = float(t_pos_x) if t_pos_x is not None else None
+        t_pos_y = float(t_pos_y) if t_pos_y is not None else None
+    except (TypeError, ValueError):
+        t_pos_x, t_pos_y = None, None
+    # margin_top：前端默认 24@720p；整体顶距 = PAD(16@720p) + margin_top
+    # 因为 drawtext y 是 baseline，中文字符 ascent≈0.85*fontsize，为让文本 top-edge≈(PAD+marginTop)，
+    # baseline 需再下移约 0.85*fontsize；但 drawtext 表达式无法引用 fontsize 变量，
+    # 这里直接用 (PAD + margin_top)@720p 缩放后作为 y（即让 baseline≈顶部内边距位置），
+    # 实际中文字符会自然向下延伸，视觉位置与前端预览（textBaseline=middle 居中到 firstLineY）一致。
+    _t_margin_top_raw = t_cfg.get("margin_top", TITLE_DEFAULT_MARGIN_TOP)
+    try:
+        _t_margin_top_720 = int(_t_margin_top_raw)
+    except (TypeError, ValueError):
+        _t_margin_top_720 = TITLE_DEFAULT_MARGIN_TOP
+    t_margin_top = _scale_title_len(TITLE_PAD_TOP + _t_margin_top_720, output_width)
+    # bottom margin（标题放在 bottom 时也支持）
+    t_margin_bottom = _scale_title_len(TITLE_PAD_TOP + TITLE_DEFAULT_MARGIN_BOTTOM, output_width)
     t_borderw = 0
     t_border_color = "#000000"
     t_box = False
@@ -449,31 +541,35 @@ def build_direct_render(
     _stroke = t_cfg.get("stroke")
     if isinstance(_stroke, dict) and _stroke.get("enabled", False):
         try:
-            t_borderw = int(float(_stroke.get("width", 2)))
+            t_borderw_720 = int(float(_stroke.get("width", 2)))
         except (TypeError, ValueError):
-            t_borderw = 2
+            t_borderw_720 = 2
+        t_borderw = max(1, _scale_title_len(t_borderw_720, output_width))
         t_border_color = str(_stroke.get("color", "#000000"))
     elif isinstance(_stroke, bool) and _stroke:
-        t_borderw = 2
+        t_borderw = max(1, _scale_title_len(2, output_width))
     # shadow
     _shadow = t_cfg.get("shadow")
     t_shadow_enabled = False
     t_shadow_color = "#000000@0.6"
-    t_shadow_x, t_shadow_y = 2, 2
+    t_shadow_x_720, t_shadow_y_720 = 2, 2
     if isinstance(_shadow, dict) and _shadow.get("enabled", False):
         t_shadow_enabled = True
         t_shadow_color = str(_shadow.get("color", "#000000@0.6"))
         try:
-            t_shadow_x = int(float(_shadow.get("offset_x", 2)))
-            t_shadow_y = int(float(_shadow.get("offset_y", 2)))
+            t_shadow_x_720 = int(float(_shadow.get("offset_x", 2)))
+            t_shadow_y_720 = int(float(_shadow.get("offset_y", 2)))
         except (TypeError, ValueError):
-            t_shadow_x, t_shadow_y = 2, 2
+            t_shadow_x_720, t_shadow_y_720 = 2, 2
     elif isinstance(_shadow, bool) and _shadow:
         t_shadow_enabled = True
-    # bold/italic：drawtext 原生无粗斜体选项；通过加大 borderw 模拟粗体
-    t_bold = bool(t_cfg.get("bold", False))
+    t_shadow_x = _scale_title_len(t_shadow_x_720, output_width)
+    t_shadow_y = _scale_title_len(t_shadow_y_720, output_width)
+    # bold/italic：drawtext 原生无粗斜体选项；通过同色描边模拟粗体
+    t_bold = bool(t_cfg.get("bold", True))  # 与 ASS 路径默认 bold=True 对齐
     if t_bold and t_borderw < 1:
-        t_borderw = 1
+        # 同色描边宽度 1@720p，按宽度缩放保证各分辨率视觉一致
+        t_borderw = max(1, _scale_title_len(1, output_width))
         t_border_color = t_color  # 用文字色描边模拟加粗
 
     # ── 解析 subtitle_config ──
@@ -482,15 +578,24 @@ def build_direct_render(
     s_font = str(s_cfg.get("font", font) or font)
     s_size_raw = s_cfg.get("size", s_cfg.get("font_size", 0))
     try:
-        s_size = int(s_size_raw) if s_size_raw else 0
+        s_size_720 = int(s_size_raw) if s_size_raw else 0
     except (TypeError, ValueError):
-        s_size = 0
-    if s_size <= 0:
-        s_size = max(int(output_height * 0.04), 20)
+        s_size_720 = 0
+    if s_size_720 <= 0:
+        s_size_720 = 24  # 字幕默认 24@720p（对齐 ass_subtitle_builder defaults size=24）
+    s_size = _scale_title_len(s_size_720, output_width)
     s_color = str(s_cfg.get("color", s_cfg.get("font_color", "#ffffff")))
-    s_position = str(s_cfg.get("position", "bottom")).lower()
-    s_margin = max(60, int(output_height * 0.06))
-    s_borderw = 2  # 字幕默认描边保证可读性
+    s_position = str(s_cfg.get("position", "bottom")).lower().strip()
+    s_pos_x = s_cfg.get("pos_x")
+    s_pos_y = s_cfg.get("pos_y")
+    try:
+        s_pos_x = float(s_pos_x) if s_pos_x is not None else None
+        s_pos_y = float(s_pos_y) if s_pos_y is not None else None
+    except (TypeError, ValueError):
+        s_pos_x, s_pos_y = None, None
+    s_margin_top = _scale_title_len(60, output_width)  # subtitle top (not commonly used)
+    s_margin_bottom = _scale_title_len(SUBTITLE_DEFAULT_MARGIN_BOTTOM, output_width)
+    s_borderw = max(1, _scale_title_len(2, output_width))  # 字幕默认描边保证可读性
     s_border_color = "#000000"
 
     # 静态字幕：static_subtitle_text 非空时构造全片长 segment（0 → total_duration）
@@ -519,7 +624,10 @@ def build_direct_render(
                 font_size=t_size,
                 font_color=t_color,
                 position=t_position,
-                margin=t_margin,
+                margin_top=t_margin_top,
+                margin_bottom=t_margin_bottom,
+                pos_x=t_pos_x,
+                pos_y=t_pos_y,
                 box_enabled=t_box,
                 box_color=t_box_color,
                 borderw=t_borderw,
@@ -548,7 +656,10 @@ def build_direct_render(
                     font_size=s_size,
                     font_color=s_color,
                     position=s_position,
-                    margin=s_margin,
+                    margin_top=s_margin_top,
+                    margin_bottom=s_margin_bottom,
+                    pos_x=s_pos_x,
+                    pos_y=s_pos_y,
                     box_enabled=False,
                     borderw=s_borderw,
                     border_color=s_border_color,

tests/unit/test_gpu_direct_pipeline.py

@@ -84,7 +84,8 @@ def _patch_pipeline_helpers(monkeypatch):
 # 基线：不传 config 保持旧默认行为
 # ---------------------------------------------------------------------------
 class TestNoConfigBackwardCompat:
-    def test_default_title_drawtext_white_bottom(self, monkeypatch):
+    def test_default_title_drawtext_white_top(self, monkeypatch):
+        """不传 title_config 时：白字、top、36@720 按 width 缩放到 64、y=71（PAD16+margin24）。"""
         import video_processing.gpu_direct_pipeline as gdp
 
         _patch_pipeline_helpers(monkeypatch)
@@ -99,14 +100,16 @@ class TestNoConfigBackwardCompat:
             clip_volumes=[1.0, 1.0],
         )
         fc = " ".join(plan.filter_complex)
-        # 默认 fontcolor=0xffffff（白色）
         assert "fontcolor=0xffffff" in fc
-        # 默认 position=bottom → y 表达式含 h-th
-        assert "h-th" in fc
-        # 默认字号：max(720*0.05,24) = 36
-        assert "fontsize=36" in fc
-        # escape 对中文无影响（只转义 :'\ ），所以中文原样出现
+        # 默认 position=top → y=71（scale(16+24)=71），不含 h-th
+        assert "y=71" in fc
+        assert "h-th" not in fc
+        # 默认字号 36@720 经 1280/720 缩放 = 64
+        assert "fontsize=64" in fc
         assert "text='默认标题'" in fc
+        # 默认粗体：drawtext 无原生粗体，用同色描边 borderw=1@720（1280/720→scale=2）模拟
+        assert "borderw=2" in fc
+        assert "bordercolor=0xffffff" in fc
 
     def test_no_subtitle_when_none(self, monkeypatch):
         import video_processing.gpu_direct_pipeline as gdp
@@ -148,9 +151,10 @@ class TestTitleStylePassthrough:
         )
         fc = " ".join(plan.filter_complex)
         assert "fontcolor=0xff0000" in fc
-        assert "fontsize=60" in fc
-        # top 位置 y=40 附近（h_th 不出现）
-        assert "y=40" in fc
+        # 60@720 按 1280/720 缩放 = 107
+        assert "fontsize=107" in fc
+        # top 位置 y=71（scale(PAD16+margin_top24)=71）
+        assert "y=71" in fc
         assert "h-th" not in fc
 
     def test_title_position_center(self, monkeypatch):
@@ -188,7 +192,8 @@ class TestTitleStylePassthrough:
             },
         )
         fc = " ".join(plan.filter_complex)
-        assert "borderw=4" in fc
+        # stroke width 4@720 经 1280/720 缩放 = 7
+        assert "borderw=7" in fc
         assert "bordercolor=0x0000ff" in fc
 
     def test_title_shadow_produces_two_drawtext_layers(self, monkeypatch):
@@ -213,8 +218,10 @@ class TestTitleStylePassthrough:
         # 阴影层 + 主字层 = 2 条 drawtext
         assert drawtext_count == 2
         joined = " ".join(plan.filter_complex)
-        assert "x=(w-text_w)/2+3" in joined
-        assert "y=h-th-" in joined and "+3" in joined
+        # shadow offset 3@720 经 1280/720 缩放 = 5；默认 position=top → y=71
+        assert "x=(w-text_w)/2+5" in joined
+        assert "y=71+5" in joined
+        assert "h-th" not in joined
 
     def test_title_font_override(self, monkeypatch):
         import video_processing.gpu_direct_pipeline as gdp
@@ -251,6 +258,131 @@ class TestTitleStylePassthrough:
         fc = " ".join(plan.filter_complex)
         assert "drawtext=" not in fc
 
+    def test_title_custom_position_uses_pct_xy(self, monkeypatch):
+        """position=custom + pos_x/pos_y 百分比 → (w-text_w)*pct, (h-text_h)*pct。"""
+        import video_processing.gpu_direct_pipeline as gdp
+
+        _patch_pipeline_helpers(monkeypatch)
+        plan = gdp.build_direct_render(
+            resolved_clips=_make_clips(1, 2.0),
+            output_width=1280,
+            output_height=720,
+            output_fps=30,
+            total_duration=2.0,
+            clip_has_audio=[True],
+            clip_volumes=[1.0],
+            title_config={
+                "text": "拖拽标题",
+                "position": "custom",
+                "pos_x": 30,
+                "pos_y": 60,
+            },
+        )
+        fc = " ".join(plan.filter_complex)
+        assert "(w-text_w)*0.3000" in fc
+        assert "(h-text_h)*0.6000" in fc
+        assert "h-th-" not in fc
+        assert "y=71" not in fc
+
+    def test_title_margin_top_respected(self, monkeypatch):
+        """margin_top 透传：100@720 → scale(16+100)=206@1280。"""
+        import video_processing.gpu_direct_pipeline as gdp
+
+        _patch_pipeline_helpers(monkeypatch)
+        plan = gdp.build_direct_render(
+            resolved_clips=_make_clips(1, 2.0),
+            output_width=1280,
+            output_height=720,
+            output_fps=30,
+            total_duration=2.0,
+            clip_has_audio=[True],
+            clip_volumes=[1.0],
+            title_config={"text": "远离顶部", "position": "top", "margin_top": 100},
+        )
+        fc = " ".join(plan.filter_complex)
+        # scale(PAD16 + margin_top100) = 116*1280/720 = 206
+        assert "y=206" in fc
+
+    def test_title_default_bold_true(self, monkeypatch):
+        """不传 bold 时默认粗体：drawtext 用同色描边 borderw 模拟。"""
+        import video_processing.gpu_direct_pipeline as gdp
+
+        _patch_pipeline_helpers(monkeypatch)
+        plan = gdp.build_direct_render(
+            resolved_clips=_make_clips(1, 2.0),
+            output_width=1280,
+            output_height=720,
+            output_fps=30,
+            total_duration=2.0,
+            clip_has_audio=[True],
+            clip_volumes=[1.0],
+            title_config={"text": "粗体"},
+        )
+        fc = " ".join(plan.filter_complex)
+        # bold=True 默认：同色描边 width=1@720 → scale=2，颜色与文字相同（白色）
+        assert "borderw=2" in fc
+        assert "bordercolor=0xffffff" in fc
+        assert "text='粗体'" in fc
+
+    def test_title_bold_false_disables_faux_bold(self, monkeypatch):
+        """显式 bold=False 时不加粗描边。"""
+        import video_processing.gpu_direct_pipeline as gdp
+
+        _patch_pipeline_helpers(monkeypatch)
+        plan = gdp.build_direct_render(
+            resolved_clips=_make_clips(1, 2.0),
+            output_width=1280,
+            output_height=720,
+            output_fps=30,
+            total_duration=2.0,
+            clip_has_audio=[True],
+            clip_volumes=[1.0],
+            title_config={"text": "细体", "bold": False},
+        )
+        fc = " ".join(plan.filter_complex)
+        # 无描边
+        assert "borderw=" not in fc
+
+    def test_title_position_bottom(self, monkeypatch):
+        """position=bottom → y=h-th-{scaled margin}。"""
+        import video_processing.gpu_direct_pipeline as gdp
+
+        _patch_pipeline_helpers(monkeypatch)
+        plan = gdp.build_direct_render(
+            resolved_clips=_make_clips(1, 2.0),
+            output_width=1280,
+            output_height=720,
+            output_fps=30,
+            total_duration=2.0,
+            clip_has_audio=[True],
+            clip_volumes=[1.0],
+            title_config={"text": "底部", "position": "bottom"},
+        )
+        fc = " ".join(plan.filter_complex)
+        # bottom margin PAD16+24=40 → scale=71
+        assert "y=h-th-71" in fc
+
+    def test_title_size_scales_by_width_not_height(self, monkeypatch):
+        """不同分辨率下同 @720 基准的 size 等比缩放：1080x1920 下 36→54。"""
+        import video_processing.gpu_direct_pipeline as gdp
+
+        _patch_pipeline_helpers(monkeypatch)
+        plan = gdp.build_direct_render(
+            resolved_clips=_make_clips(1, 2.0),
+            output_width=1080,
+            output_height=1920,
+            output_fps=30,
+            title_text="竖屏标题",
+            total_duration=2.0,
+            clip_has_audio=[True],
+            clip_volumes=[1.0],
+        )
+        fc = " ".join(plan.filter_complex)
+        # default size 36@720 → 1080w = 54
+        assert "fontsize=54" in fc
+        # top margin 40@720 → 60
+        assert "y=60" in fc
+
 
 # ---------------------------------------------------------------------------
 # 字幕：静态 subtitle_text + ASR segments
@@ -300,7 +432,10 @@ class TestSubtitlePassthrough:
         assert "text='第一句'" in fc
         assert "text='第二句'" in fc
         assert "fontcolor=0x0000ff" in fc
-        assert "fontsize=28" in fc
+        # sub size 28@720 经 1280/720 缩放 = 50
+        assert "fontsize=50" in fc
+        # bottom margin 60@720 → 107
+        assert "y=h-th-107" in fc
 
     def test_subtitle_disabled_hides_subs(self, monkeypatch):
         import video_processing.gpu_direct_pipeline as gdp
@@ -509,16 +644,18 @@ class TestCombinedConfig:
             bgm_config={"volume": 0.2, "fade_in": 0.5, "fade_out": 1.0},
         )
         fc = " ".join(plan.filter_complex)
-        # 标题
+        # 标题：size 50@720 → 89，top margin 40@720 → 71，stroke 2@720 → 4
         assert "text='主标题'" in fc
         assert "fontcolor=0xffff00" in fc
-        assert "fontsize=50" in fc
-        assert "y=40" in fc
-        assert "borderw=2" in fc
-        # 字幕
+        assert "fontsize=89" in fc
+        assert "y=71" in fc
+        assert "borderw=4" in fc
+        # 字幕：size 24@720 → 43，bottom margin 60@720 → 107
         assert "text='成片全字幕'" in fc
+        assert "fontsize=43" in fc
+        assert "y=h-th-107" in fc
         assert "fontcolor=0xffffff" in fc
-        assert "fontsize=24" in fc
+        # subtitle 默认 bold=True 也会加同色描边（width=1→2）；但若主标题已有 stroke 不影响字幕独立 borderw=4（s 默认 2 像素@720→scale=4）
         # BGM
         assert "volume=0.200" in fc
         assert "afade=t=in:st=0:d=0.50" in fc