merge: Preserve all streams when producing web-optimized videos (!1215)

View MR for information: https://activitypub.software/TransFem-org/Sharkey/-/merge_requests/1215

Approved-by: dakkar <dakkar@thenautilus.net>
Approved-by: Marie <github@yuugi.dev>

packages/backend/src/core/VideoProcessingService.ts

@@ -102,6 +102,7 @@ export class VideoProcessingService {
 					.format(outputFormat) // Specify output format
 					.addOutputOptions('-c copy') // Copy streams without re-encoding
 					.addOutputOptions('-movflags +faststart')
+					.addOutputOptions('-map 0')
 					.on('error', reject)
 					.on('end', async () => {
 						try {