198 lines
8.0 KiB
Python
198 lines
8.0 KiB
Python
"""用 FFmpeg 合成平台兼容的无音轨商品轮播视频。"""
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from __future__ import annotations
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import asyncio
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import json
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import os
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import tempfile
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from collections.abc import Awaitable, Callable
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from dataclasses import dataclass
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from pathlib import Path
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from config import get_settings
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from services.storage import (
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ResourceSizeLimitError,
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download_bytes,
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image_extension,
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local_path,
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normalize_image_bytes,
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read_local_bytes,
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)
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class VideoRenderError(RuntimeError):
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"""FFmpeg 无法生成符合预设的商品视频。"""
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class VideoRenderCancelled(VideoRenderError):
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"""任务在 FFmpeg 运行期间被用户取消。"""
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@dataclass(frozen=True)
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class RenderedVideo:
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data: bytes
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duration_seconds: float
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width: int
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height: int
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def slide_seconds_for(count: int) -> float:
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"""按图片数量维持约 9–13 秒成片，并确保两图时也不会过短。"""
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by_count = {2: 4.5, 3: 3.5, 4: 3.0, 5: 2.8}
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try:
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return by_count[count]
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except KeyError as exc:
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raise VideoRenderError("轮播视频只支持 2–5 张图片") from exc
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async def _read_image(url: str) -> tuple[bytes, str]:
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path = local_path(url)
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if path is not None:
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return read_local_bytes(path), ""
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return await download_bytes(url, max_bytes=get_settings().image_download_max_bytes)
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async def _run_process(
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args: list[str],
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*,
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should_cancel: Callable[[], Awaitable[bool]],
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timeout_seconds: int,
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) -> None:
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try:
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process = await asyncio.create_subprocess_exec(
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*args,
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stdout=asyncio.subprocess.DEVNULL,
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stderr=asyncio.subprocess.PIPE,
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)
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except FileNotFoundError as exc:
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raise VideoRenderError(
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f"未找到视频合成工具「{args[0]}」。请安装 FFmpeg，并配置 VIDEO_FFMPEG_PATH 为其可执行文件的绝对路径。"
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) from exc
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try:
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waited = 0.0
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while process.returncode is None:
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if await should_cancel():
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process.terminate()
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try:
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await asyncio.wait_for(process.wait(), timeout=5)
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except TimeoutError:
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process.kill()
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await process.wait()
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raise VideoRenderCancelled("视频任务已取消")
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await asyncio.sleep(0.25)
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waited += 0.25
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if waited > timeout_seconds:
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process.kill()
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await process.wait()
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raise VideoRenderError(f"视频渲染超过 {timeout_seconds} 秒，请减少图片后重试")
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stderr = (await process.stderr.read()).decode("utf-8", errors="replace") if process.stderr else ""
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if process.returncode != 0:
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raise VideoRenderError(f"FFmpeg 渲染失败：{stderr[-800:] or '未知错误'}")
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finally:
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if process.returncode is None:
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process.kill()
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await process.wait()
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async def _probe(path: Path) -> dict:
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settings = get_settings()
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try:
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process = await asyncio.create_subprocess_exec(
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settings.video_ffprobe_path,
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"-v", "error", "-show_entries", "format=duration,size:stream=codec_name,width,height,pix_fmt",
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"-of", "json", str(path),
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stdout=asyncio.subprocess.PIPE,
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stderr=asyncio.subprocess.PIPE,
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)
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except FileNotFoundError as exc:
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raise VideoRenderError(
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f"未找到视频校验工具「{settings.video_ffprobe_path}」。请安装 FFmpeg，并配置 VIDEO_FFPROBE_PATH 为其可执行文件的绝对路径。"
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) from exc
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stdout, stderr = await process.communicate()
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if process.returncode != 0:
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raise VideoRenderError(f"无法校验视频输出：{stderr.decode('utf-8', errors='replace')[-400:]}")
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try:
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return json.loads(stdout)
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except json.JSONDecodeError as exc:
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raise VideoRenderError("FFprobe 未返回可解析的视频信息") from exc
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async def render_slideshow(
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source_urls: list[str],
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*,
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should_cancel: Callable[[], Awaitable[bool]],
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) -> RenderedVideo:
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"""将已入库图片缩放留白后串为 MP4，严禁接收调用方任意命令参数。"""
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settings = get_settings()
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if not settings.video_ffmpeg_path or not settings.video_ffprobe_path:
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raise VideoRenderError("未配置 FFmpeg 或 FFprobe 可执行路径")
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count = len(source_urls)
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seconds = slide_seconds_for(count)
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transition = settings.video_transition_seconds
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with tempfile.TemporaryDirectory(prefix="osk-video-") as temp_dir:
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workdir = Path(temp_dir)
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inputs: list[Path] = []
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for index, url in enumerate(source_urls):
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if await should_cancel():
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raise VideoRenderCancelled("视频任务已取消")
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data, content_type = await _read_image(url)
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normalized = normalize_image_bytes(data, max_bytes=settings.image_download_max_bytes)
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suffix = image_extension(normalized.data, content_type or normalized.content_type)
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image_path = workdir / f"input-{index}{suffix}"
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image_path.write_bytes(normalized.data)
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inputs.append(image_path)
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output_path = workdir / "result.mp4"
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args = [settings.video_ffmpeg_path, "-y", "-hide_banner", "-loglevel", "error"]
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for image_path in inputs:
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args.extend(["-loop", "1", "-framerate", str(settings.video_fps), "-t", str(seconds), "-i", str(image_path)])
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filters: list[str] = []
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for index in range(count):
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filters.append(
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f"[{index}:v]scale={settings.video_width}:{settings.video_height}:"
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"force_original_aspect_ratio=decrease,"
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f"pad={settings.video_width}:{settings.video_height}:(ow-iw)/2:(oh-ih):color=white,"
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"setsar=1,format=yuv420p"
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f"[slide{index}]"
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)
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previous = "slide0"
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accumulated = seconds
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for index in range(1, count):
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output = f"fade{index}"
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filters.append(
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f"[{previous}][slide{index}]xfade=transition=fade:duration={transition}:"
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f"offset={accumulated - transition:.3f}[{output}]"
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)
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previous = output
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accumulated += seconds - transition
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filters.append(f"[{previous}]fps={settings.video_fps},format=yuv420p[video]")
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args.extend([
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"-filter_complex", ";".join(filters), "-map", "[video]",
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"-an", "-c:v", "libx264", "-profile:v", "high", "-pix_fmt", "yuv420p",
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"-preset", "medium", "-crf", str(settings.video_crf),
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"-maxrate", settings.video_max_rate, "-bufsize", settings.video_buffer_size,
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"-movflags", "+faststart", str(output_path),
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])
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await _run_process(args, should_cancel=should_cancel, timeout_seconds=settings.video_render_timeout_seconds)
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if not output_path.is_file():
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raise VideoRenderError("FFmpeg 未生成视频文件")
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file_size = output_path.stat().st_size
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if file_size > settings.video_max_bytes:
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raise ResourceSizeLimitError(settings.video_max_bytes, file_size)
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probe = await _probe(output_path)
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stream = next((item for item in probe.get("streams", []) if item.get("codec_name") == "h264"), None)
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if stream is None:
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raise VideoRenderError("输出视频不是 H.264 编码")
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width, height = int(stream.get("width", 0)), int(stream.get("height", 0))
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duration = float((probe.get("format") or {}).get("duration", 0))
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if (width, height) != (settings.video_width, settings.video_height):
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raise VideoRenderError(f"输出分辨率异常：{width} × {height}")
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if not 0 < duration <= settings.video_max_duration_seconds:
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raise VideoRenderError(f"输出视频时长异常：{duration:.1f} 秒")
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data = output_path.read_bytes()
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if len(data) != file_size:
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raise VideoRenderError("读取视频输出失败")
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return RenderedVideo(data=data, duration_seconds=duration, width=width, height=height)
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