Fix muxing

dist/server/services/muxer.js

@@ -4,26 +4,80 @@ var __importDefault = (this && this.__importDefault) || function (mod) {
 };
 Object.defineProperty(exports, "__esModule", { value: true });
 exports.muxAudioDescription = muxAudioDescription;
+exports.muxMixedAudioDescription = muxMixedAudioDescription;
 const child_process_1 = require("child_process");
 const path_1 = __importDefault(require("path"));
+const fs_1 = __importDefault(require("fs"));
 function muxAudioDescription(videoPath, audioPath, outputPath) {
-    const ext = path_1.default.extname(outputPath).toLowerCase();
-    const isMkv = ext === '.mkv';
-    const cmd = [
-        'ffmpeg -v error',
-        `-i "${videoPath}"`,
-        `-i "${audioPath}"`,
-        '-map 0:v',
-        '-map 0:a?',
-        '-map 1:a',
-        '-c:v copy',
-        '-c:a copy',
-        isMkv
-            ? '-metadata:s:a:1 title="Audio Description"'
-            : '-metadata:s:a:1 title="Audio Description"',
-        `"${outputPath}"`,
-        '-y'
-    ].join(' ');
-    (0, child_process_1.execSync)(cmd);
+    if (!fs_1.default.existsSync(videoPath)) {
+        throw new Error(`mux: video not found: ${videoPath}`);
+    }
+    if (!fs_1.default.existsSync(audioPath)) {
+        throw new Error(`mux: audio not found: ${audioPath}`);
+    }
+    fs_1.default.mkdirSync(path_1.default.dirname(outputPath), { recursive: true });
+    // Argv form — no shell, no quoting issues, and -y is a global option (placed
+    // up front, not after the output). Stderr is captured so failures aren't
+    // silent.
+    const args = [
+        '-y',
+        '-v', 'error',
+        '-i', videoPath,
+        '-i', audioPath,
+        '-map', '0:v',
+        '-map', '0:a?',
+        '-map', '1:a',
+        '-c:v', 'copy',
+        '-c:a', 'copy',
+        '-metadata:s:a:1', 'title=Audio Description',
+        '-disposition:a:1', 'visual_impaired',
+        outputPath,
+    ];
+    const result = (0, child_process_1.spawnSync)('ffmpeg', args, { shell: false, encoding: 'utf-8' });
+    if (result.error) {
+        throw new Error(`mux: ffmpeg failed to start: ${result.error.message}`);
+    }
+    if (result.status !== 0) {
+        const tail = (result.stderr || '').trim().split('\n').slice(-5).join(' | ');
+        throw new Error(`mux: ffmpeg exited ${result.status}: ${tail || '(no stderr)'}`);
+    }
+}
+function muxMixedAudioDescription(videoPath, audioPath, outputPath) {
+    if (!fs_1.default.existsSync(videoPath)) {
+        throw new Error(`mux: video not found: ${videoPath}`);
+    }
+    if (!fs_1.default.existsSync(audioPath)) {
+        throw new Error(`mux: audio not found: ${audioPath}`);
+    }
+    fs_1.default.mkdirSync(path_1.default.dirname(outputPath), { recursive: true });
+    // Sidechain-ducked mix: original audio dips when the AD track is speaking,
+    // then both are summed into a single output audio stream. The AD track is
+    // already a full-length file that is silent between description segments
+    // (built by combineAudioSegments), so asplit gives us one copy to drive the
+    // sidechain detector and another to mix in on top.
+    const filterGraph = '[1:a]asplit=2[ad_mix][ad_sc];' +
+        '[0:a][ad_sc]sidechaincompress=threshold=0.03:ratio=20:attack=5:release=300:level_sc=2[ducked];' +
+        '[ducked][ad_mix]amix=inputs=2:duration=first:dropout_transition=0:normalize=0[aout]';
+    const args = [
+        '-y',
+        '-v', 'error',
+        '-i', videoPath,
+        '-i', audioPath,
+        '-filter_complex', filterGraph,
+        '-map', '0:v',
+        '-map', '[aout]',
+        '-c:v', 'copy',
+        '-c:a', 'aac',
+        '-b:a', '192k',
+        outputPath,
+    ];
+    const result = (0, child_process_1.spawnSync)('ffmpeg', args, { shell: false, encoding: 'utf-8' });
+    if (result.error) {
+        throw new Error(`mux: ffmpeg failed to start: ${result.error.message}`);
+    }
+    if (result.status !== 0) {
+        const tail = (result.stderr || '').trim().split('\n').slice(-5).join(' | ');
+        throw new Error(`mux: ffmpeg exited ${result.status}: ${tail || '(no stderr)'}`);
+    }
 }
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