init

src/packaging.ts

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+import { join } from 'node:path';
+import { execMP4Box } from './utils';
+import type { VideoProfile } from './types';
+
+/**
+ * Package MP4 files into DASH format using MP4Box
+ * Stage 2: Light work - just packaging, no encoding
+ * Creates one master MPD manifest with all profiles
+ */
+export async function packageToDash(
+  mp4Files: Map<string, string>,
+  outputDir: string,
+  profiles: VideoProfile[],
+  segmentDuration: number
+): Promise<string> {
+  const manifestPath = join(outputDir, 'manifest.mpd');
+  
+  // Build MP4Box command
+  const args = [
+    '-dash', String(segmentDuration * 1000), // MP4Box expects milliseconds
+    '-frag', String(segmentDuration * 1000),
+    '-rap', // Force segments to start with random access points
+    '-segment-name', '$RepresentationID$_$Number$',
+    '-out', manifestPath
+  ];
+
+  // Add all MP4 files with their profile IDs
+  for (const profile of profiles) {
+    const mp4Path = mp4Files.get(profile.name);
+    if (!mp4Path) {
+      throw new Error(`MP4 file not found for profile: ${profile.name}`);
+    }
+    
+    // Add video track with representation ID
+    args.push(`${mp4Path}#video:id=${profile.name}`);
+    // Add audio track (shared across all profiles)
+    if (profile === profiles[0]) {
+      args.push(`${mp4Path}#audio:id=audio`);
+    }
+  }
+
+  // Execute MP4Box
+  await execMP4Box(args);
+
+  // MP4Box creates files in the same directory as output MPD
+  // Move segment files to profile subdirectories for clean structure
+  await organizeSegments(outputDir, profiles);
+
+  // Update MPD to reflect new file structure with subdirectories
+  await updateManifestPaths(manifestPath, profiles);
+
+  return manifestPath;
+}
+
+/**
+ * Organize segments into profile subdirectories
+ * MP4Box creates all files in one directory, we organize them
+ */
+async function organizeSegments(
+  outputDir: string,
+  profiles: VideoProfile[]
+): Promise<void> {
+  const { readdir, rename, mkdir } = await import('node:fs/promises');
+  
+  // Create profile subdirectories
+  for (const profile of profiles) {
+    const profileDir = join(outputDir, profile.name);
+    await mkdir(profileDir, { recursive: true });
+  }
+  
+  // Create audio subdirectory
+  const audioDir = join(outputDir, 'audio');
+  await mkdir(audioDir, { recursive: true });
+  
+  // Get all files in output directory
+  const files = await readdir(outputDir);
+  
+  // Move segment files to their respective directories
+  for (const file of files) {
+    // Skip manifest
+    if (file === 'manifest.mpd') {
+      continue;
+    }
+    
+    // Move audio files to audio/ directory
+    if (file.startsWith('audio_') || file === 'audio_init.m4s') {
+      const oldPath = join(outputDir, file);
+      const newPath = join(audioDir, file);
+      await rename(oldPath, newPath);
+      continue;
+    }
+    
+    // Move video segment files to their profile directories
+    for (const profile of profiles) {
+      if (file.startsWith(`${profile.name}_`)) {
+        const oldPath = join(outputDir, file);
+        const newPath = join(outputDir, profile.name, file);
+        await rename(oldPath, newPath);
+        break;
+      }
+    }
+  }
+}
+
+/**
+ * Update MPD manifest to reflect subdirectory structure
+ */
+async function updateManifestPaths(
+  manifestPath: string,
+  profiles: VideoProfile[]
+): Promise<void> {
+  const { readFile, writeFile } = await import('node:fs/promises');
+  
+  let mpd = await readFile(manifestPath, 'utf-8');
+  
+  // MP4Box uses $RepresentationID$ template variable
+  // Replace: media="$RepresentationID$_$Number$.m4s" 
+  // With:    media="$RepresentationID$/$RepresentationID$_$Number$.m4s"
+  
+  mpd = mpd.replace(
+    /media="\$RepresentationID\$_\$Number\$\.m4s"/g,
+    'media="$RepresentationID$/$RepresentationID$_$Number$.m4s"'
+  );
+  
+  // Replace: initialization="$RepresentationID$_.mp4"
+  // With:    initialization="$RepresentationID$/$RepresentationID$_.mp4"
+  
+  mpd = mpd.replace(
+    /initialization="\$RepresentationID\$_\.mp4"/g,
+    'initialization="$RepresentationID$/$RepresentationID$_.mp4"'
+  );
+  
+  await writeFile(manifestPath, mpd, 'utf-8');
+}
+