允许后端任务

app/api/media.ts

@@ -82,6 +82,60 @@ export type ExtractedVideoFrame = {
   timestampMs: number;
 };
 
+export type ExtractedAudio = {
+  buffer: Buffer;
+  contentType: string;
+  ext: string;
+};
+
+export type ExtractedAudioSegment = ExtractedAudio & {
+  index: number;
+  startMs: number;
+  endMs: number;
+};
+
+type AudioFormat = "mp3" | "aac" | "wav";
+
+function resolveAudioEncoding(format: AudioFormat, bitrateKbps: number) {
+  if (format === "mp3") {
+    return {
+      ext: "mp3",
+      contentType: "audio/mpeg",
+      codecArgs: ["-c:a", "libmp3lame", "-b:a", `${bitrateKbps}k`],
+    };
+  }
+
+  if (format === "aac") {
+    return {
+      ext: "m4a",
+      contentType: "audio/mp4",
+      codecArgs: [
+        "-c:a",
+        "aac",
+        "-b:a",
+        `${bitrateKbps}k`,
+        "-movflags",
+        "+faststart",
+      ],
+    };
+  }
+
+  return {
+    ext: "wav",
+    contentType: "audio/wav",
+    codecArgs: [
+      "-f",
+      "wav",
+      "-acodec",
+      "pcm_s16le",
+      "-ar",
+      "44100",
+      "-ac",
+      "2",
+    ],
+  };
+}
+
 /**
  * 使用 ffprobe 获取视频时长（毫秒）
  */
@@ -234,8 +288,8 @@ export async function extractVideoFrames(
  */
 export async function extractAudio(
   videoBuffer: Buffer,
-  opts?: { format?: "mp3" | "aac" | "wav"; bitrateKbps?: number },
-): Promise<{ buffer: Buffer; contentType: string; ext: string } | null> {
+  opts?: { format?: AudioFormat; bitrateKbps?: number },
+): Promise<ExtractedAudio | null> {
   const ffmpegCmd = process.env.FFMPEG_PATH || "ffmpeg";
   const tmpDir = os.tmpdir();
   const base = `dy_${Date.now()}_${Math.random().toString(36).slice(2, 8)}`;
@@ -243,47 +297,8 @@ export async function extractAudio(
 
   const format = opts?.format ?? "mp3";
   const bitrate = Math.max(32, Math.min(512, opts?.bitrateKbps ?? 192)); // 安全范围 32~512 kbps
-
-  // 根据目标格式设置输出路径、MIME 与编码参数
-  let outPath = "";
-  let contentType = "";
-  let ext = "";
-  let codecArgs: string[] = [];
-
-  if (format === "mp3") {
-    ext = "mp3";
-    contentType = "audio/mpeg";
-    outPath = path.join(tmpDir, `${base}.${ext}`);
-    codecArgs = ["-c:a", "libmp3lame", "-b:a", `${bitrate}k`];
-  } else if (format === "aac") {
-    // 使用 m4a 容器更通用
-    ext = "m4a";
-    contentType = "audio/mp4";
-    outPath = path.join(tmpDir, `${base}.${ext}`);
-    codecArgs = [
-      "-c:a",
-      "aac",
-      "-b:a",
-      `${bitrate}k`,
-      "-movflags",
-      "+faststart",
-    ];
-  } else {
-    // wav
-    ext = "wav";
-    contentType = "audio/wav";
-    outPath = path.join(tmpDir, `${base}.${ext}`);
-    codecArgs = [
-      "-f",
-      "wav",
-      "-acodec",
-      "pcm_s16le",
-      "-ar",
-      "44100",
-      "-ac",
-      "2",
-    ];
-  }
+  const { ext, contentType, codecArgs } = resolveAudioEncoding(format, bitrate);
+  const outPath = path.join(tmpDir, `${base}.${ext}`);
 
   try {
     await fs.writeFile(inPath, videoBuffer);
@@ -320,3 +335,88 @@ export async function extractAudio(
     } catch {}
   }
 }
+
+/**
+ * 将视频音轨按时间切成多个音频片段，避免长视频单次请求体过大。
+ */
+export async function extractAudioSegments(
+  videoBuffer: Buffer,
+  opts: {
+    durationMs: number;
+    segmentDurationMs: number;
+    format?: AudioFormat;
+    bitrateKbps?: number;
+  },
+): Promise<ExtractedAudioSegment[]> {
+  const ffmpegCmd = process.env.FFMPEG_PATH || "ffmpeg";
+  const tmpDir = os.tmpdir();
+  const base = `dy_${Date.now()}_${Math.random().toString(36).slice(2, 8)}`;
+  const inPath = path.join(tmpDir, `${base}.mp4`);
+
+  const format = opts.format ?? "mp3";
+  const bitrate = Math.max(32, Math.min(512, opts.bitrateKbps ?? 128));
+  const segmentDurationMs = Math.max(1000, opts.segmentDurationMs);
+  const durationMs = Math.max(0, opts.durationMs);
+  const { ext, contentType, codecArgs } = resolveAudioEncoding(format, bitrate);
+  const outPaths: string[] = [];
+
+  try {
+    await fs.writeFile(inPath, videoBuffer);
+
+    const segments: ExtractedAudioSegment[] = [];
+    let index = 0;
+    for (let startMs = 0; startMs < durationMs; startMs += segmentDurationMs) {
+      const endMs = Math.min(durationMs, startMs + segmentDurationMs);
+      if (endMs - startMs < 500) continue;
+
+      const outPath = path.join(tmpDir, `${base}_${index}.${ext}`);
+      outPaths.push(outPath);
+
+      const args = [
+        "-hide_banner",
+        "-loglevel",
+        "error",
+        "-ss",
+        (startMs / 1000).toFixed(3),
+        "-t",
+        ((endMs - startMs) / 1000).toFixed(3),
+        "-i",
+        inPath,
+        "-vn",
+        ...codecArgs,
+        "-y",
+        outPath,
+      ];
+      await execFileAsync(ffmpegCmd, args, { windowsHide: true });
+      segments.push({
+        buffer: await fs.readFile(outPath),
+        contentType,
+        ext,
+        index,
+        startMs,
+        endMs,
+      });
+      index += 1;
+    }
+
+    return segments;
+  } catch (error) {
+    if (isMissingExecutableError(error)) {
+      console.warn(
+        "系统未检测到 ffmpeg，可安装并配置 PATH 或设置 FFMPEG_PATH 后启用音频分片提取。",
+      );
+      return [];
+    }
+    console.warn(`提取音频分片失败: ${getErrorMessage(error)}`);
+    throw error;
+  } finally {
+    try {
+      await fs.unlink(inPath);
+    } catch {}
+    for (const outPath of outPaths) {
+      try {
+        await fs.unlink(outPath);
+      } catch {}
+    }
+  }
+}