app.py

from fastapi import FastAPI, Query
from fastapi.responses import JSONResponse
import subprocess
import base64
import os
import tempfile

app = FastAPI(title="MP4 Thumbnail from URL (FFmpeg)")

@app.get("/")
def get_thumbnail(
    file: str = Query(..., description="Direct URL to .mp4 file"),
    seconds: float = Query(20.0, ge=0.0, description="Seconds to seek (can be float, default 20)"),
):
    try:
        with tempfile.NamedTemporaryFile(suffix=".jpg", delete=False) as tmp_file:
            output_path = tmp_file.name

        # FFmpeg command – seek BEFORE input for remote HTTP efficiency
        cmd = [
            "ffmpeg",
            "-user_agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36",
            "-ss", str(seconds),       # seek early (fast for remote)
            "-i", file,
            "-frames:v", "1",
            "-q:v", "5",               # good quality
            "-f", "image2",
            output_path
        ]

        result = subprocess.run(
            cmd,
            capture_output=True,
            text=True,
            timeout=60
        )

        if result.returncode != 0:
            error_detail = result.stderr.strip() or "FFmpeg exited with error (no details)"
            os.unlink(output_path)  # cleanup
            return JSONResponse(
                status_code=400,
                content={
                    "error": "FFmpeg failed to process video",
                    "ffmpeg_error": error_detail,
                    "return_code": result.returncode
                }
            )

        if not os.path.exists(output_path) or os.path.getsize(output_path) < 1000:
            os.unlink(output_path)
            return JSONResponse(
                status_code=400,
                content={"error": "No valid frame extracted (empty or tiny output file)"}
            )

        with open(output_path, "rb") as f:
            img_bytes = f.read()

        os.unlink(output_path)  # cleanup

        img_base64 = base64.b64encode(img_bytes).decode("utf-8")

        return {
            "base64": img_base64,
            "format": "jpeg",
            "taken_at_seconds": seconds,
            "data_url": f"data:image/jpeg;base64,{img_base64}",
            "debug": "Success – frame extracted"
        }

    except subprocess.TimeoutExpired:
        return JSONResponse(status_code=504, content={"error": "Timeout – source too slow or unreachable"})
    except Exception as e:
        return JSONResponse(status_code=500, content={"error": f"Unexpected error: {str(e)}"})