migrate to root dir

lib/pipeline/audio.ts

@@ -0,0 +1,125 @@
+import { spawn } from "child_process";
+import { StoryConfig } from "./config";
+import * as path from "path";
+import * as fs from "fs";
+import ffmpeg from "ffmpeg-static";
+import ffprobe from "ffprobe-static";
+
+export function getDuration(file: string): Promise<number> {
+  const ffprobePath: string = (ffprobe as unknown as { path: string }).path;
+  const args = ["-v", "error", "-show_entries", "format=duration", "-of", "default=noprint_wrappers=1:nokey=1", file];
+
+  const ffprobeProcess = spawn(ffprobePath, args);
+
+  let duration = "";
+  ffprobeProcess.stdout.on("data", (data: Buffer) => {
+    duration += data.toString();
+  });
+
+  return new Promise<number>((resolve, reject) => {
+    ffprobeProcess.on("close", (code: number | null) => {
+      if (code === 0) {
+        resolve(parseFloat(duration));
+      } else {
+        reject(new Error(`ffprobe process exited with code ${code}`));
+      }
+    });
+  });
+}
+
+export async function getChunkDuration(chunkPath: string): Promise<number> {
+  return getDuration(chunkPath);
+}
+
+export async function generateSilence(duration: number, outputFile: string): Promise<void> {
+  const ffmpegPath: string = (ffmpeg as unknown as string) || "ffmpeg";
+  const args = ["-y", "-f", "lavfi", "-i", `anullsrc=r=44100:cl=stereo:d=${duration}`, outputFile];
+
+  const ffmpegProcess = spawn(ffmpegPath, args);
+
+  return new Promise<void>((resolve, reject) => {
+    ffmpegProcess.on("close", (code: number | null) => {
+      if (code === 0) {
+        resolve();
+      } else {
+        reject(new Error(`ffmpeg process exited with code ${code}`));
+      }
+    });
+  });
+}
+
+export async function combineAudio(storyName: string, storyConfig: StoryConfig, audioFiles: string[]): Promise<void> {
+  const ffmpegPath: string = (ffmpeg as unknown as string) || "ffmpeg";
+  const introFile = path.resolve("stories", storyName, storyConfig.config.intro_audio_file);
+  const outroFile = path.resolve("stories", storyName, storyConfig.config.outro_audio_file);
+  const finalAudioDir = path.resolve("stories", storyName, "final_audio");
+  const tempAudioFile = path.join(finalAudioDir, "temp.mp3");
+  const finalAudioFile = path.join(finalAudioDir, "final.mp3");
+  const backgroundMusicFile = path.resolve("stories", storyName, storyConfig.config.background_music_file);
+
+  fs.mkdirSync(finalAudioDir, { recursive: true });
+
+  const allFiles = [introFile, ...audioFiles.map((f) => path.resolve(f)), outroFile];
+  const fileList = allFiles.map((f) => `file '${f.replace(/'/g, "'\\''")}'`).join("\n");
+  const listFile = path.resolve("stories", storyName, "filelist.txt");
+  fs.writeFileSync(listFile, fileList);
+
+  const concatArgs = ["-y", "-f", "concat", "-safe", "0", "-i", listFile, "-c", "copy", tempAudioFile];
+
+  const concatProcess = spawn(ffmpegPath, concatArgs);
+
+  await new Promise<void>((resolve, reject) => {
+    concatProcess.on("close", (code: number | null) => {
+      if (code === 0) {
+        resolve();
+      } else {
+        reject(new Error(`ffmpeg concat process exited with code ${code}`));
+      }
+    });
+  });
+
+  const duration = await getDuration(tempAudioFile);
+
+  if (!fs.existsSync(backgroundMusicFile)) {
+    await new Promise<void>((resolve, reject) => {
+      const args = ["-y", "-i", tempAudioFile, "-c:a", "libmp3lame", "-q:a", "4", finalAudioFile];
+      const p = spawn(ffmpegPath, args);
+      p.on("close", (code: number | null) =>
+        code === 0 ? resolve() : reject(new Error(`ffmpeg copy failed ${code}`))
+      );
+    });
+    return;
+  }
+
+  const bgVolume = "0.2";
+  const mixArgs = [
+    "-y",
+    "-i",
+    tempAudioFile,
+    "-stream_loop",
+    "-1",
+    "-i",
+    backgroundMusicFile,
+    "-filter_complex",
+    `[1:a]volume=${bgVolume},atrim=0:${duration},asetpts=N/SR/TB[bg];[0:a][bg]amix=inputs=2:duration=first:dropout_transition=0[a]`,
+    "-map",
+    "[a]",
+    "-c:a",
+    "libmp3lame",
+    "-q:a",
+    "4",
+    finalAudioFile,
+  ];
+
+  const mixProcess = spawn(ffmpegPath, mixArgs);
+
+  return new Promise<void>((resolve, reject) => {
+    mixProcess.on("close", (code: number | null) => {
+      if (code === 0) {
+        resolve();
+      } else {
+        reject(new Error(`ffmpeg mix process exited with code ${code}`));
+      }
+    });
+  });
+}