323 lines
8.9 KiB
TypeScript
323 lines
8.9 KiB
TypeScript
import { execFile } from "node:child_process";
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import { promises as fs } from "node:fs";
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import os from "node:os";
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import path from "node:path";
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import { promisify } from "node:util";
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const execFileAsync = promisify(execFile);
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function getErrorMessage(error: unknown) {
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return error instanceof Error ? error.message : String(error);
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}
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function getErrorCode(error: unknown) {
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return typeof error === "object" && error !== null && "code" in error
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? String((error as { code?: unknown }).code)
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: null;
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}
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function isMissingExecutableError(error: unknown) {
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return (
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getErrorCode(error) === "ENOENT" ||
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/not found|is not recognized/i.test(getErrorMessage(error))
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);
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}
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/**
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* 使用 ffmpeg 从视频二进制中提取第一帧，返回 JPEG buffer
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*/
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export async function extractFirstFrame(
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videoBuffer: Buffer,
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): Promise<{ buffer: Buffer; contentType: string; ext: string } | null> {
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const ffmpegCmd = process.env.FFMPEG_PATH || "ffmpeg";
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const tmpDir = os.tmpdir();
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const base = `dy_${Date.now()}_${Math.random().toString(36).slice(2, 8)}`;
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const inPath = path.join(tmpDir, `${base}.mp4`);
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const outPath = path.join(tmpDir, `${base}.jpg`);
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try {
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await fs.writeFile(inPath, videoBuffer);
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const args = [
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"-hide_banner",
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"-loglevel",
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"error",
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"-ss",
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"0",
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"-i",
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inPath,
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"-frames:v",
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"1",
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"-q:v",
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"2",
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"-f",
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"image2",
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"-y",
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outPath,
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];
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await execFileAsync(ffmpegCmd, args, { windowsHide: true });
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const img = await fs.readFile(outPath);
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return { buffer: img, contentType: "image/jpeg", ext: "jpg" };
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} catch (error) {
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if (isMissingExecutableError(error)) {
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console.warn(
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"系统未检测到 ffmpeg，可安装并配置 PATH 或设置 FFMPEG_PATH 后启用封面提取。",
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);
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return null;
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}
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throw error;
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} finally {
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try {
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await fs.unlink(inPath);
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} catch {}
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try {
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await fs.unlink(outPath);
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} catch {}
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}
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}
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export type ExtractedVideoFrame = {
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buffer: Buffer;
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contentType: string;
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ext: string;
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timestampMs: number;
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};
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/**
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* 使用 ffprobe 获取视频时长（毫秒）
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*/
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export async function getVideoDuration(
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videoBuffer: Buffer,
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): Promise<number | null> {
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const ffprobeCmd = process.env.FFPROBE_PATH || "ffprobe";
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const tmpDir = os.tmpdir();
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const base = `dy_${Date.now()}_${Math.random().toString(36).slice(2, 8)}`;
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const inPath = path.join(tmpDir, `${base}.mp4`);
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try {
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await fs.writeFile(inPath, videoBuffer);
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const args = [
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"-v",
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"error",
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"-show_entries",
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"format=duration",
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"-of",
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"default=noprint_wrappers=1:nokey=1",
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inPath,
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];
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const { stdout } = await execFileAsync(ffprobeCmd, args, {
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windowsHide: true,
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});
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const durationSeconds = parseFloat(stdout.trim());
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if (Number.isNaN(durationSeconds)) return null;
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return Math.round(durationSeconds * 1000); // 转换为毫秒
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} catch (error) {
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if (isMissingExecutableError(error)) {
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console.warn(
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"系统未检测到 ffprobe，可安装并配置 PATH 或设置 FFPROBE_PATH 后启用时长提取。",
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);
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return null;
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}
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console.warn(`获取视频时长失败: ${getErrorMessage(error)}`);
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return null;
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} finally {
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try {
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await fs.unlink(inPath);
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} catch {}
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}
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}
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function getFrameTimestamps(durationMs: number | null, count: number) {
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if (!durationMs || durationMs <= 0) {
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return Array.from({ length: count }, (_, index) => index * 1000);
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}
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if (count === 1) return [0];
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const maxTimestamp = Math.max(0, durationMs - 200);
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if (count === 3) {
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return [
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Math.min(maxTimestamp, Math.max(0, Math.round(durationMs * 0.1))),
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Math.min(maxTimestamp, Math.max(0, Math.round(durationMs * 0.5))),
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Math.min(maxTimestamp, Math.max(0, Math.round(durationMs * 0.9))),
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];
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}
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return Array.from({ length: count }, (_, index) => {
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const ratio = count === 1 ? 0 : index / (count - 1);
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return Math.min(maxTimestamp, Math.max(0, Math.round(durationMs * ratio)));
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});
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}
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/**
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* 使用 ffmpeg 从视频中提取固定数量的 JPEG 帧。
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*/
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export async function extractVideoFrames(
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videoBuffer: Buffer,
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opts?: { count?: number; durationMs?: number | null },
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): Promise<ExtractedVideoFrame[]> {
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const ffmpegCmd = process.env.FFMPEG_PATH || "ffmpeg";
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const tmpDir = os.tmpdir();
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const base = `dy_${Date.now()}_${Math.random().toString(36).slice(2, 8)}`;
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const inPath = path.join(tmpDir, `${base}.mp4`);
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const count = Math.max(1, opts?.count ?? 3);
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const outPaths = Array.from({ length: count }, (_, index) =>
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path.join(tmpDir, `${base}_${index}.jpg`),
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);
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try {
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await fs.writeFile(inPath, videoBuffer);
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const durationMs =
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opts?.durationMs ?? (await getVideoDuration(videoBuffer));
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const timestamps = getFrameTimestamps(durationMs, count);
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const frames: ExtractedVideoFrame[] = [];
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for (let index = 0; index < count; index++) {
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const timestampSeconds = Math.max(0, timestamps[index] / 1000).toFixed(3);
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const args = [
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"-hide_banner",
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"-loglevel",
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"error",
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"-ss",
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timestampSeconds,
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"-i",
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inPath,
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"-frames:v",
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"1",
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"-q:v",
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"3",
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"-vf",
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"scale=768:-2:force_original_aspect_ratio=decrease",
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"-f",
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"image2",
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"-y",
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outPaths[index],
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];
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await execFileAsync(ffmpegCmd, args, { windowsHide: true });
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frames.push({
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buffer: await fs.readFile(outPaths[index]),
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contentType: "image/jpeg",
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ext: "jpg",
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timestampMs: timestamps[index],
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});
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}
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return frames;
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} catch (error) {
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if (isMissingExecutableError(error)) {
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console.warn(
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"系统未检测到 ffmpeg，可安装并配置 PATH 或设置 FFMPEG_PATH 后启用视频帧提取。",
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);
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return [];
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}
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throw error;
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} finally {
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try {
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await fs.unlink(inPath);
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} catch {}
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for (const outPath of outPaths) {
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try {
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await fs.unlink(outPath);
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} catch {}
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}
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}
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}
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/**
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* 使用 ffmpeg 将视频二进制转换为音频，返回音频 Buffer
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*
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* 默认输出 mp3，可通过 opts.format 指定 'mp3' | 'aac' | 'wav'
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* - mp3: 使用 libmp3lame，contentType 为 'audio/mpeg'
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* - aac: 输出 m4a 容器（AAC 编码），contentType 为 'audio/mp4'
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* - wav: PCM 16-bit，44100Hz，双声道，contentType 为 'audio/wav'
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*
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* 若系统未安装 ffmpeg 或未在 PATH 中，返回 null 并给出提示。
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*/
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export async function extractAudio(
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videoBuffer: Buffer,
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opts?: { format?: "mp3" | "aac" | "wav"; bitrateKbps?: number },
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): Promise<{ buffer: Buffer; contentType: string; ext: string } | null> {
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const ffmpegCmd = process.env.FFMPEG_PATH || "ffmpeg";
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const tmpDir = os.tmpdir();
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const base = `dy_${Date.now()}_${Math.random().toString(36).slice(2, 8)}`;
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const inPath = path.join(tmpDir, `${base}.mp4`);
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const format = opts?.format ?? "mp3";
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const bitrate = Math.max(32, Math.min(512, opts?.bitrateKbps ?? 192)); // 安全范围 32~512 kbps
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// 根据目标格式设置输出路径、MIME 与编码参数
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let outPath = "";
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let contentType = "";
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let ext = "";
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let codecArgs: string[] = [];
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if (format === "mp3") {
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ext = "mp3";
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contentType = "audio/mpeg";
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outPath = path.join(tmpDir, `${base}.${ext}`);
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codecArgs = ["-c:a", "libmp3lame", "-b:a", `${bitrate}k`];
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} else if (format === "aac") {
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// 使用 m4a 容器更通用
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ext = "m4a";
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contentType = "audio/mp4";
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outPath = path.join(tmpDir, `${base}.${ext}`);
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codecArgs = [
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"-c:a",
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"aac",
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"-b:a",
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`${bitrate}k`,
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"-movflags",
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"+faststart",
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];
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} else {
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// wav
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ext = "wav";
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contentType = "audio/wav";
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outPath = path.join(tmpDir, `${base}.${ext}`);
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codecArgs = [
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"-f",
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"wav",
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"-acodec",
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"pcm_s16le",
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"-ar",
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"44100",
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"-ac",
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"2",
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];
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}
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try {
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await fs.writeFile(inPath, videoBuffer);
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const args = [
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"-hide_banner",
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"-loglevel",
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"error",
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"-i",
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inPath,
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"-vn", // 丢弃视频流
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...codecArgs,
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"-y",
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outPath,
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];
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await execFileAsync(ffmpegCmd, args, { windowsHide: true });
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const audio = await fs.readFile(outPath);
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return { buffer: audio, contentType, ext };
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} catch (error) {
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if (isMissingExecutableError(error)) {
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console.warn(
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"系统未检测到 ffmpeg，可安装并配置 PATH 或设置 FFMPEG_PATH 后启用音频提取。",
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);
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return null;
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}
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// 一些环境可能缺少特定编码器（如 libmp3lame），提示并抛出原始错误
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console.warn(`提取音频失败: ${getErrorMessage(error)}`);
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throw error;
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} finally {
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try {
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await fs.unlink(inPath);
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} catch {}
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try {
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if (outPath) await fs.unlink(outPath);
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} catch {}
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}
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}
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