bvandeusen
1a2a120da1
Generates 400px-max thumbnails: PNG with alpha preserved when source has
transparency, JPEG (q=85, progressive) otherwise. Storage layout is
/images/thumbs/{sha[:3]}/{sha}.{jpg|png} so each prefix bucket holds at
most ~4k files (16^3 buckets across all possible SHAs).
Video path uses ffmpeg's first-frame snapshot at ~5% offset; we have a
1-second floor for short clips. ffmpeg call has a 60s timeout. Video
tests are deferred to FC-2e's integration suite where transcoding is
also wired up.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
103 lines
3.3 KiB
Python
103 lines
3.3 KiB
Python
"""Image + video thumbnail generation.
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Images go through Pillow; videos go through ffmpeg's first-frame snapshot
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at ~5% into the runtime (avoids fade-ins/title cards while still being a
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representative frame).
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Thumbnails are stored at /images/thumbs/{sha[:3]}/{sha}.jpg or .png; the
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3-char prefix bucket avoids hot single-directory inode pressure.
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"""
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import subprocess
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from dataclasses import dataclass
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from pathlib import Path
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from PIL import Image
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THUMB_MAX_PX = 400
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JPEG_QUALITY = 85
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FFMPEG_TIMEOUT_SECONDS = 60
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@dataclass(frozen=True)
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class ThumbnailResult:
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path: Path
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width: int
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height: int
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mime: str
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def thumbnail_path_for(sha256_hex: str, *, alpha: bool, root: Path) -> Path:
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ext = ".png" if alpha else ".jpg"
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bucket = sha256_hex[:3]
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return root / "thumbs" / bucket / f"{sha256_hex}{ext}"
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class Thumbnailer:
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def __init__(self, images_root: Path):
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self.images_root = images_root
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def generate_image_thumbnail(
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self, source: Path, sha256_hex: str
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) -> ThumbnailResult:
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"""Reads source, fits inside THUMB_MAX_PX × THUMB_MAX_PX preserving
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aspect ratio. Writes PNG if source has alpha, else JPEG.
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"""
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with Image.open(source) as im:
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im.load()
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has_alpha = im.mode in ("RGBA", "LA") or (
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im.mode == "P" and "transparency" in im.info
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)
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if has_alpha:
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im = im.convert("RGBA")
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else:
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im = im.convert("RGB")
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im.thumbnail((THUMB_MAX_PX, THUMB_MAX_PX), Image.Resampling.LANCZOS)
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dest = thumbnail_path_for(sha256_hex, alpha=has_alpha, root=self.images_root)
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dest.parent.mkdir(parents=True, exist_ok=True)
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if has_alpha:
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im.save(dest, "PNG", optimize=True)
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mime = "image/png"
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else:
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im.save(dest, "JPEG", quality=JPEG_QUALITY, optimize=True, progressive=True)
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mime = "image/jpeg"
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return ThumbnailResult(path=dest, width=im.width, height=im.height, mime=mime)
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def generate_video_thumbnail(
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self, source: Path, sha256_hex: str, duration_seconds: float | None = None
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) -> ThumbnailResult:
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"""Snapshots a frame ~5% into the video via ffmpeg, then runs that
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frame through the image-thumbnail pipeline.
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duration_seconds is optional; if absent, we snapshot at the 1-second
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mark which is a reasonable fallback for short clips.
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"""
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offset = max(1.0, (duration_seconds or 20.0) * 0.05)
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tmp = self.images_root / "thumbs" / "_tmp" / f"{sha256_hex}.png"
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tmp.parent.mkdir(parents=True, exist_ok=True)
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try:
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cmd = [
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"ffmpeg",
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"-ss",
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f"{offset:.2f}",
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"-i",
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str(source),
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"-frames:v",
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"1",
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"-vf",
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f"scale='if(gt(iw,ih),{THUMB_MAX_PX},-2)':'if(gt(iw,ih),-2,{THUMB_MAX_PX})'",
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"-y",
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str(tmp),
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]
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subprocess.run(
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cmd,
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check=True,
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capture_output=True,
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timeout=FFMPEG_TIMEOUT_SECONDS,
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)
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return self.generate_image_thumbnail(tmp, sha256_hex)
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finally:
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if tmp.exists():
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tmp.unlink()
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