add buildPipelineCommand: single FFmpeg command for sub extraction, audio cleanup, transcode

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server/services/ffmpeg.ts

@@ -361,6 +361,110 @@ export function buildExtractOnlyCommand(
 	return parts.join(' ');
 }
 
+/**
+ * Build a single FFmpeg command that:
+ * 1. Extracts subtitles to sidecar files
+ * 2. Remuxes with reordered/filtered audio
+ * 3. Transcodes incompatible audio codecs
+ */
+export function buildPipelineCommand(
+	item: MediaItem,
+	streams: MediaStream[],
+	decisions: (StreamDecision & { stream?: MediaStream })[]
+): { command: string; extractedFiles: Array<{ path: string; language: string | null; codec: string | null; is_forced: number; is_hearing_impaired: number }> } {
+	const inputPath = item.file_path;
+	const ext = inputPath.match(/\.([^.]+)$/)?.[1] ?? 'mkv';
+	const tmpPath = inputPath.replace(/\.[^.]+$/, `.tmp.${ext}`);
+	const basePath = inputPath.replace(/\.[^.]+$/, '');
+
+	// --- Subtitle extraction outputs ---
+	const extractionEntries = computeExtractionEntries(streams, basePath);
+	const subOutputArgs: string[] = [];
+	for (const e of extractionEntries) {
+		subOutputArgs.push(`-map 0:s:${e.typeIdx}`, `-c:s ${e.codecArg}`, shellQuote(e.outPath));
+	}
+
+	// --- Kept streams for remuxed output ---
+	// Enrich decisions with stream data
+	const enriched = decisions.map(d => {
+		const stream = d.stream ?? streams.find(s => s.id === d.stream_id);
+		return { ...d, stream: stream! };
+	}).filter(d => d.action === 'keep' && d.stream);
+
+	// Sort by type priority then target_index
+	const typeOrder: Record<string, number> = { Video: 0, Audio: 1, Data: 2, EmbeddedImage: 3 };
+	enriched.sort((a, b) => {
+		const ta = typeOrder[a.stream.type] ?? 9;
+		const tb = typeOrder[b.stream.type] ?? 9;
+		if (ta !== tb) return ta - tb;
+		return (a.target_index ?? 0) - (b.target_index ?? 0);
+	});
+
+	// Build -map flags
+	const maps = buildMaps(streams, enriched.map(d => ({ stream: d.stream, dec: d })));
+
+	// Build per-stream codec flags
+	const codecFlags: string[] = ['-c:v copy'];
+	let audioIdx = 0;
+	for (const d of enriched) {
+		if (d.stream.type === 'Audio') {
+			if (d.transcode_codec) {
+				codecFlags.push(`-c:a:${audioIdx} ${d.transcode_codec}`);
+				// For EAC3, set a reasonable bitrate based on channel count
+				if (d.transcode_codec === 'eac3') {
+					const bitrate = (d.stream.channels ?? 2) >= 6 ? '640k' : '256k';
+					codecFlags.push(`-b:a:${audioIdx} ${bitrate}`);
+				}
+			} else {
+				codecFlags.push(`-c:a:${audioIdx} copy`);
+			}
+			audioIdx++;
+		}
+	}
+
+	// If no audio transcoding, simplify to -c copy (covers video + audio)
+	const hasTranscode = enriched.some(d => d.transcode_codec);
+	const finalCodecFlags = hasTranscode ? codecFlags : ['-c copy'];
+
+	// Disposition + metadata flags for audio
+	const streamFlags = buildStreamFlags(enriched.map(d => ({ stream: d.stream, dec: d })));
+
+	// Assemble command
+	const parts: string[] = [
+		'ffmpeg', '-y',
+		'-i', shellQuote(inputPath),
+	];
+
+	// Subtitle extraction outputs first
+	parts.push(...subOutputArgs);
+
+	// Map flags for remuxed output
+	parts.push(...maps);
+
+	// Codec flags
+	parts.push(...finalCodecFlags);
+
+	// Stream flags (disposition, metadata)
+	parts.push(...streamFlags);
+
+	// Output file
+	parts.push(shellQuote(tmpPath));
+
+	const command = parts.join(' ')
+		+ ` && mv ${shellQuote(tmpPath)} ${shellQuote(inputPath)}`;
+
+	return {
+		command,
+		extractedFiles: extractionEntries.map(e => ({
+			path: e.outPath,
+			language: e.stream.language,
+			codec: e.stream.codec,
+			is_forced: e.stream.is_forced ? 1 : 0,
+			is_hearing_impaired: e.stream.is_hearing_impaired ? 1 : 0,
+		})),
+	};
+}
+
 /** Safely quote a path for shell usage. */
 export function shellQuote(s: string): string {
 	return `'${s.replace(/'/g, "'\\''")}'`;