diff --git a/server/src/repositories/media.repository.ts b/server/src/repositories/media.repository.ts
index c1e8cfd234..577b8b2c33 100644
--- a/server/src/repositories/media.repository.ts
+++ b/server/src/repositories/media.repository.ts
@@ -241,6 +241,7 @@ export class MediaRepository {
         formatLongName: results.format.format_long_name,
         duration: this.parseFloat(results.format.duration),
         bitrate: this.parseInt(results.format.bit_rate),
+        tags: results.format.tags,
       },
       videoStreams: results.streams
         .filter((stream) => stream.codec_type === 'video' && !stream.disposition?.attached_pic)
diff --git a/server/src/services/media.service.spec.ts b/server/src/services/media.service.spec.ts
index d64e0088eb..b51989f777 100644
--- a/server/src/services/media.service.spec.ts
+++ b/server/src/services/media.service.spec.ts
@@ -2099,6 +2099,58 @@ describe(MediaService.name, () => {
       expect(mocks.media.transcode).not.toHaveBeenCalled();
     });
 
+    it('should remux fragmented MP4 (fMP4) files based on probe metadata', async () => {
+      mocks.media.probe.mockResolvedValue(probeStub.fragmentedMp4);
+      mocks.systemMetadata.get.mockResolvedValue({ ffmpeg: { transcode: TranscodePolicy.Required } });
+      await sut.handleVideoConversion({ id: 'video-id' });
+      expect(mocks.media.transcode).toHaveBeenCalledWith(
+        '/original/path.ext',
+        expect.any(String),
+        expect.objectContaining({
+          inputOptions: expect.any(Array),
+          outputOptions: expect.arrayContaining(['-c:v copy', '-c:a copy', '-movflags faststart']),
+          twoPass: false,
+        }),
+      );
+      expect(mocks.asset.upsertFile).toHaveBeenCalledWith(
+        expect.objectContaining({
+          type: AssetFileType.EncodedVideo,
+          isEdited: false,
+        }),
+      );
+    });
+
+    it('should remux fragmented MP4 when only compatible_brands indicates fragmentation', async () => {
+      mocks.media.probe.mockResolvedValue(probeStub.fragmentedMp4CompatibleBrands);
+      mocks.systemMetadata.get.mockResolvedValue({ ffmpeg: { transcode: TranscodePolicy.Required } });
+      await sut.handleVideoConversion({ id: 'video-id' });
+      expect(mocks.media.transcode).toHaveBeenCalledWith(
+        '/original/path.ext',
+        expect.any(String),
+        expect.objectContaining({
+          outputOptions: expect.arrayContaining(['-c:v copy', '-c:a copy', '-movflags faststart']),
+          twoPass: false,
+        }),
+      );
+    });
+
+    it('should not include encoding options when remuxing', async () => {
+      mocks.media.probe.mockResolvedValue(probeStub.fragmentedMp4);
+      mocks.systemMetadata.get.mockResolvedValue({ ffmpeg: { transcode: TranscodePolicy.Required } });
+      await sut.handleVideoConversion({ id: 'video-id' });
+      expect(mocks.media.transcode).toHaveBeenCalledWith(
+        '/original/path.ext',
+        expect.any(String),
+        expect.objectContaining({
+          outputOptions: expect.not.arrayContaining([
+            expect.stringContaining('-preset'),
+            expect.stringContaining('-crf'),
+            expect.stringContaining('scale'),
+          ]),
+        }),
+      );
+    });
+
     it('should not scale resolution if no target resolution', async () => {
       mocks.assetJob.getForVideoConversion.mockResolvedValue({ ...asset, ...probeStub.videoStream2160p });
       mocks.systemMetadata.get.mockResolvedValue({
diff --git a/server/src/services/media.service.ts b/server/src/services/media.service.ts
index 19b1688e88..feac7b0c0d 100644
--- a/server/src/services/media.service.ts
+++ b/server/src/services/media.service.ts
@@ -56,6 +56,7 @@ interface UpsertFileOptions {
 }
 
 type ThumbnailAsset = NonNullable<Awaited<ReturnType<AssetJobRepository['getForGenerateThumbnailJob']>>>;
+const FRAGMENTED_MP4_BRANDS = ['iso5', 'iso6', 'dash', 'msdh', 'msix', 'cmfc'];
 
 @Injectable()
 export class MediaService extends BaseService {
@@ -703,7 +704,7 @@ export class MediaService extends BaseService {
     }
   }
 
-  private isRemuxRequired(ffmpegConfig: SystemConfigFFmpegDto, { formatName, formatLongName }: VideoFormat): boolean {
+  private isRemuxRequired(ffmpegConfig: SystemConfigFFmpegDto, { formatName, formatLongName, tags }: VideoFormat): boolean {
     if (ffmpegConfig.transcode === TranscodePolicy.Disabled) {
       return false;
     }
@@ -714,8 +715,25 @@ export class MediaService extends BaseService {
     };
 
     const name = (formatLongName ? formatLongNameMapping[formatLongName] : undefined) ?? (formatName as VideoContainer);
+    if (name !== VideoContainer.Mp4 && !ffmpegConfig.acceptedContainers.includes(name)) {
+      return true;
+    }
 
-    return name !== VideoContainer.Mp4 && !ffmpegConfig.acceptedContainers.includes(name);
+    if (!formatName?.includes('mp4') && formatLongName !== 'QuickTime / MOV') {
+      return false;
+    }
+
+    const majorBrand = tags?.major_brand;
+    if (majorBrand && FRAGMENTED_MP4_BRANDS.includes(majorBrand)) {
+      return true;
+    }
+
+    const compatibleBrands = tags?.compatible_brands;
+    if (!compatibleBrands) {
+      return false;
+    }
+
+    return FRAGMENTED_MP4_BRANDS.some((brand) => compatibleBrands.includes(brand));
   }
 
   isSRGB({
diff --git a/server/src/types.ts b/server/src/types.ts
index 27995e841f..8cf8b2d7e1 100644
--- a/server/src/types.ts
+++ b/server/src/types.ts
@@ -136,6 +136,7 @@ export interface VideoFormat {
   formatLongName?: string;
   duration: number;
   bitrate: number;
+  tags?: Record<string, string>;
 }
 
 export interface ImageDimensions {
diff --git a/server/src/utils/media.ts b/server/src/utils/media.ts
index aea821d6d5..e45b430c5f 100644
--- a/server/src/utils/media.ts
+++ b/server/src/utils/media.ts
@@ -152,6 +152,13 @@ export class BaseConfig implements VideoCodecSWConfig {
       twoPass: this.eligibleForTwoPass(),
       progress: { frameCount: video.frameCount, percentInterval: 5 },
     } as TranscodeCommand;
+
+    // Skip two-pass and encoder-specific options when we're only remuxing streams.
+    if (target === TranscodeTarget.None) {
+      options.twoPass = false;
+      return options;
+    }
+
     if ([TranscodeTarget.All, TranscodeTarget.Video].includes(target)) {
       const filters = this.getFilterOptions(video);
       if (filters.length > 0) {
diff --git a/server/test/fixtures/media.stub.ts b/server/test/fixtures/media.stub.ts
index 77534fd6cb..3d99dbee6a 100644
--- a/server/test/fixtures/media.stub.ts
+++ b/server/test/fixtures/media.stub.ts
@@ -380,6 +380,24 @@ export const videoInfoStub = {
     ...probeStubDefault,
     videoStreams: [{ ...probeStubDefaultVideoStream[0], codecName: 'h264' }],
   }),
+  fragmentedMp4: Object.freeze<VideoInfo>({
+    ...probeStubDefault,
+    videoStreams: [{ ...probeStubDefaultVideoStream[0], codecName: 'h264' }],
+    format: {
+      ...probeStubDefaultFormat,
+      formatName: 'mov,mp4,m4a,3gp,3g2,mj2',
+      tags: { major_brand: 'iso6', compatible_brands: 'isomiso6dashmp41' },
+    },
+  }),
+  fragmentedMp4CompatibleBrands: Object.freeze<VideoInfo>({
+    ...probeStubDefault,
+    videoStreams: [{ ...probeStubDefaultVideoStream[0], codecName: 'h264' }],
+    format: {
+      ...probeStubDefaultFormat,
+      formatName: 'mov,mp4,m4a,3gp,3g2,mj2',
+      tags: { major_brand: 'isom', compatible_brands: 'isomiso6dashmp41' },
+    },
+  }),
   videoStreamAvi: Object.freeze<VideoInfo>({
     ...probeStubDefault,
     videoStreams: [{ ...probeStubDefaultVideoStream[0], codecName: 'h264' }],