unnecessary argument

server/src/services/transcoding.service.spec.ts

@@ -223,7 +223,6 @@ describe(TranscodingService.name, () => {
       '50',
       '-crf',
       '23',
-      '-start_at_zero',
       '-copyts',
       '-r',
       '50130000/2012441',
@@ -368,13 +367,12 @@ describe(TranscodingService.name, () => {
 
       const args = mocks.process.spawn.mock.calls[0][1] as string[];
       if (expected === 0) {
-        expect(args).toEqual(expect.arrayContaining(['-copyts', '-start_at_zero', '-avoid_negative_ts', 'disabled']));
+        expect(args).toEqual(expect.arrayContaining(['-copyts', '-avoid_negative_ts', 'disabled']));
         expect(args).not.toContain('-ss');
       } else {
         expect(args).toEqual(
           expect.arrayContaining(['-ss', String(expected), '-copyts', '-avoid_negative_ts', 'disabled']),
         );
-        expect(args).not.toContain('-start_at_zero');
       }
     });
   });

server/src/utils/media.ts

@@ -153,10 +153,6 @@ export class BaseConfig implements VideoCodecSWConfig {
       ...this.getPresetOptions(),
       ...this.getBitrateOptions(),
       ...this.getEncoderOptions(),
-      // -start_at_zero only applies meaningfully when seekSeconds is 0.
-      // Combined with -ss N -copyts, it would shift the first frame to t=0
-      // and break tfdt alignment with the playlist.
-      ...(options.seekSeconds ? [] : ['-start_at_zero']),
       '-copyts',
       '-r',
       `${options.packetCount * options.timeBase}/${options.totalDuration}`,