feat(music-lab): pipeline 영상·썸네일 생성

music-lab/app/pipeline/thumb.py

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+"""썸네일 생성 — 영상 5초 프레임 추출 + 텍스트 오버레이."""
+import os
+import subprocess
+import logging
+from PIL import Image, ImageDraw, ImageFont
+
+from . import storage
+
+logger = logging.getLogger("music-lab.thumb")
+THUMB_TIMEOUT_S = 60
+
+
+class ThumbGenerationError(Exception):
+    pass
+
+
+def generate(*, pipeline_id: int, video_path: str,
+             track_title: str = "", overlay_text: bool = True) -> dict:
+    out_path = os.path.join(storage.pipeline_dir(pipeline_id), "thumbnail.jpg")
+    cmd = ["ffmpeg", "-y", "-i", video_path,
+           "-ss", "00:00:05", "-vframes", "1", "-q:v", "2", out_path]
+    result = subprocess.run(cmd, capture_output=True, text=True, timeout=THUMB_TIMEOUT_S)
+    if result.returncode != 0:
+        raise ThumbGenerationError(f"ffmpeg 썸네일 실패: {result.stderr[:300]}")
+
+    if overlay_text and track_title:
+        _overlay_title(out_path, track_title)
+
+    return {"url": storage.media_url(pipeline_id, "thumbnail.jpg"), "used_fallback": False}
+
+
+def _overlay_title(path: str, title: str) -> None:
+    try:
+        with Image.open(path) as src:
+            img = src.convert("RGB")
+        try:
+            font = ImageFont.truetype("/usr/share/fonts/truetype/dejavu/DejaVuSans-Bold.ttf", 80)
+        except OSError:
+            font = ImageFont.load_default()
+        draw = ImageDraw.Draw(img)
+        # 하단 30% 영역에 검정 반투명 박스 + 흰 글씨
+        w, h = img.size
+        box_h = int(h * 0.3)
+        with Image.new("RGBA", (w, box_h), (0, 0, 0, 160)) as overlay:
+            img.paste(overlay, (0, h - box_h), overlay)
+        bbox = draw.textbbox((0, 0), title, font=font)
+        tw = bbox[2] - bbox[0]
+        draw.text(((w - tw) // 2, h - box_h + 30), title, fill=(255, 255, 255), font=font)
+        img.save(path, "JPEG", quality=92)
+    except Exception as e:
+        logger.warning("썸네일 오버레이 실패: %s", e)