feat: Jellyfin SyncPlay support by irican-f · Pull Request #735 · DonutWare/Fladder

irican-f · 2026-02-03T11:37:42Z

Pull Request Description

Adds Jellyfin SyncPlay support so users can watch media together in sync across devices.

Backend: WebSocket connection to Jellyfin for real-time commands; REST API for group create/join/leave, pause/unpause, seek, buffering/ready; NTP-like time sync for command scheduling; duplicate command handling and buffering-aware playback.
UI: SyncPlay FAB and badge in the app shell; bottom sheet to create/join/leave groups and see participants; command indicator (syncing pause/play/seek); native Android command overlay when using the native player.
Lifecycle: Reconnect WebSocket and rejoin group on app resume (mobile); Web skipped for background behavior.
L10n: English and French for all SyncPlay strings.
Docs: docs/syncplay-implementation.md documents the protocol and architecture.

Issue Being Fixed

Feature request: SyncPlay support for watching together with other Jellyfin clients.

Screenshots / Recordings

Screenshot of SyncPlay FAB and group sheet
Screenshot of command indicator (e.g. "Syncing pause...") during sync
(Optional) Short recording: join group from two devices, pause/unpause/seek in sync

fladder_syncplay_demo_beta_compressed.mp4

Checklist

If a new package was added, did you ensure it works for all supported platforms? Is the package well maintained
(Added: web_socket_channel ^3.0.3 — used for SyncPlay WebSocket. pub.dev; cross-platform.)
Check that any changes are related to the issue at hand.

PartyDonut · 2026-02-03T18:27:15Z

Probably better to move these callbacks to the ExoPlayer and listen to state changes from the player itself.

PartyDonut · 2026-02-03T18:29:46Z

Same here I'm not even sure we need to use these callbacks.

The player already reports back it's state to flutter we could probably use that for reporting seek/pause/play states. That way we don't rely on any additional kotlin implementation.

PartyDonut · 2026-02-03T18:32:57Z

+    modifier: Modifier = Modifier
+) {
+    val syncPlayState by VideoPlayerObject.syncPlayCommandState.collectAsState()
+    val visible = syncPlayState.processing && syncPlayState.commandType != null


This will recalculate whenever the state changes. Probably fine for a small composable but lets change this to

Suggested change

val visible = syncPlayState.processing && syncPlayState.commandType != null

val visible by remember(syncPlayState) {

derivedStateOf {

syncPlayState.processing && syncPlayState.commandType != null

}

}

PartyDonut · 2026-02-03T18:36:24Z

+                Translate(
+                    callback = { cb ->
+                        when (syncPlayState.commandType) {
+                            "Pause" -> Localized.syncPlayCommandPausing(cb)


Create a enum for this. Pigeon supports enum's that way both flutter/kotlin are in sync and we don't rely on Strings.

PartyDonut · 2026-02-03T18:36:56Z

    }

+    // SyncPlay command state for overlay
+    data class SyncPlayCommandState(


Let's put this in pigeon.

PartyDonut · 2026-02-03T20:51:59Z

          key: const Key("Search"),
          onPressed: () => context.router.navigate(LibrarySearchRoute()),
          child: const Icon(IconsaxPlusLinear.search_normal_1),
        );


Not sure about the position of this widget. Let's remove it from the dashboard for now.
We should not be using multiple fabs together in a single navigation rail.

We'll have to find a better spot.

PartyDonut · 2026-02-03T20:52:50Z

+    final isProcessing = ref.watch(syncPlayProvider.select((s) => s.isProcessingCommand));
+    final processingCommand = ref.watch(syncPlayProvider.select((s) => s.processingCommandType));
+
+    final (icon, color) = switch (groupState) {


Extension please.

PartyDonut · 2026-02-03T20:54:17Z

+
+  String _getProcessingText(BuildContext context, String? command) {
+    return switch (command) {
+      'Pause' => context.localized.syncPlaySyncingPause,


This is re-used quite a lot just adding a reminder to replace this with the enum and extension method.

PartyDonut · 2026-02-03T20:57:56Z

+    _loadGroups();
+  }
+
+  Future<void> _loadGroups() async {


Would be cleaner to lift this state out of the widget and put it in a provider.

PartyDonut · 2026-02-03T20:59:08Z

  flutter_native_splash: ^2.4.7
  macos_window_utils: ^1.9.0
-
+  web_socket_channel: ^3.0.3


Let's move it to "# Network and HTTP" group.

PartyDonut

First of thanks for implementing this, pretty big PR. But something a lot of people where requesting 👍🏼.

Works pretty well for the most part, some notes/quirks though. These are some initial findings will have to go over it after some changes.

About the UI itself. I left some comments about UI choices. However I will probably go over it myself to make some changes to bring it more in line with Fladder as it currently is.

UX:
We should show a loading indicator when any of the users press a play button. Now it has to load for a bit before the playback starts because Fladder is still synchronising.

When a player “stops” playback should all other participants return to the previous screen as well?

Architecture:
Currently most of the calls inside of the.UI go to videoplayerprovider but it now either calls the original player.pause or a new syncprovider.pause.
Like mentioned in the comments it would be better to listen to the players state stream and adjust everything based on that.

Bugs:
Playback stops working when syncplay becomes out of sync. Leaving/creating a group does nothing to change this state.
Fladder starts playback and finishes loading the video but it remains in a “paused” state as if it’s awaiting the syncplay to synchronize.

Sometimes “play” commands seem to not propagate to other users

PartyDonut · 2026-02-03T21:07:24Z

Also mentioned in some comments. But there is a lot of re-formatting making it difficult to review the changes.

Please re-format all files using the .vscode/settings.json. The biggest issue being the 120 line length currently not being used in your formatter.

fmrozvezev · 2026-03-09T23:48:24Z

Hi! What's the status of this PR? Are the fixes discussed above still needed, or has everything been fixed?

I'm curious because I'm really looking forward to this feature. Thanks for such a great app!

irican-f · 2026-03-10T17:20:15Z

Hi !
I'll push the last remaining fixes soon and do some tests on different devices again before requesting a new review

BlackShadeOSS · 2026-03-19T15:47:58Z

I you need someone to test it out I can help.

irican-f · 2026-03-22T21:01:36Z

I've pushed the fixes and added sync correction (SpeedToSync and SkipToSync) that mirrors the behavior of the syncplay plugin on the official jellyfin-web.

@PartyDonut I did not change the added UI for the syncplay. If you have an idea of how it should look I can implement it or we can merge this PR to another branch where you can make the UI changes

PartyDonut · 2026-03-29T15:56:45Z

Thanks for the improvements, had a quick test it does seem more stable then previously.

I will have a closer look next week.
A few small things I noticed now.

When we are in a group and the users presses play nothing really happens, however in the background it is starting the playback. We should show a "loading" overlay/pop-up for all the people in that group so users don't start pressing play multiple times.

Can we also have a "user has joined" pop-up. Currently the groups creator does not see a message.

If any of the users stops playback the other users keep on viewing is this the intended behavior? If yes should a user be able to join back?

About the UI, it's fine to leave it as is when you are done with your work on the PR I will just merge this and create a new PR for easier reviewing.

fmrozvezev · 2026-04-10T17:56:21Z

Hi! I built a build based on this PR and noticed the following:

The next episode switcher isn't working correctly. When I press the button to start an episode, it starts right at the end of the timeline.

Sometimes, after pausing and unpausing, someone in the group gets kicked out and has to rejoin, but there's no notification about leaving the group.

Do you need any examples from me in the form of screenshots, screen recordings, or logs?

The server logs show nothing unusual, but the client logs only show errors, which are also blank.

PartyDonut

Sorry for the late response, have been a bit busy. Also sorry about the merge conflicts quite a lot of re-work needed to get music working.

I took a quick glance through the files, at this point there is no way for me to properly review this PR.

There are a lot of files that are marked as changed but are not related to the PR at hand (might be because of the music re-work?), at this point the best path forward would be to re-base it on develop make sure all the changes are related to the sync-play functionality.

JenteJan · 2026-06-07T18:22:13Z

While testing this branch I hit a bug: starting playback from Fladder in a SyncPlay group didn't start it on the official clients — TV episodes never started (movies did), and "Continue Watching" restarted the group from 0:00. Verified against both the official Jellyfin web client and the LG webOS app.

Root cause: _playSyncPlay sends a single-item queue, but the official client always queues the whole series (with PlayingItemPosition at the chosen episode) — a lone single-episode queue isn't started by official clients. Movies are single-item by nature, so they worked and hid the bug. The resume position was also dropped, since the SyncPlay path never resolved model.startDuration() the way the local playback path does.

Fix: I opened a PR against the syncplay branch — irican-f#2 — mirroring the local path: build the queue via collectQueue (full series for an episode/series/season, single item for a movie), resolve Series/Season → next-up episode, send the whole series with the correct playingItemPosition, and fall back to the resolved item's saved resume position. Feel free to merge or cherry-pick it.

Removes generated-file drift so the PR diff shows only SyncPlay-related changes (per maintainer review on DonutWare#735). Non-SyncPlay generated files (account/credentials/boxset/etc.) now match develop and drop out of the diff.

Revert files that syncplay only reformatted (import order, wrapping, blank lines) with no functional change, so the PR diff contains only SyncPlay-related changes (per maintainer review on DonutWare#735).

…appers

…ation

…d docs

irican-f · 2026-06-28T14:02:16Z

Thanks for the feedback. You were right that the diff was unreviewable. I've rebased onto the current develop and stripped everything back to SyncPlay-only changes.

Rebased onto the latest develop, resolving conflicts against the recent rework.
The bulk of the noise was generated-file churn (*.freezed.dart, *.g.dart, *.mapper.dart, the Swagger client) my branch had regenerated them against an older base, so they showed up as unrelated changes. I've regenerated everything cleanly on top of develop, so only the generated files that SyncPlay actually owns remain.
Dropped a handful of incidental, non-SyncPlay edits (whitespace/reformatting) that had crept in.
Restructured the work into 6 logical commits (models + Pigeon, providers/websocket, player/wrappers, UI, native Android, l10n/tests/docs) to make review easier.

Happy to split further or adjust anything if it helps the review.

PartyDonut reviewed Feb 3, 2026

View reviewed changes

PartyDonut requested changes Feb 3, 2026

View reviewed changes

PartyDonut added the feature New feature or request label Feb 3, 2026

irican-f requested a review from PartyDonut March 22, 2026 21:23

irican-f force-pushed the syncplay branch from cf27190 to 0246010 Compare May 8, 2026 13:48

PartyDonut requested changes Jun 7, 2026

View reviewed changes

JenteJan mentioned this pull request Jun 7, 2026

fix(syncplay): send full series queue and resume position on initiate irican-f/Fladder-Maktep#2

Merged

JenteJan mentioned this pull request Jun 8, 2026

Bring SyncPlay up to develop + clean the #735 diff (series-queue & pause fixes) irican-f/Fladder-Maktep#3

Open

irican-f added 6 commits June 28, 2026 15:04

feat(syncplay): add SyncPlay models and Pigeon contracts

29ce55d

feat(syncplay): add SyncPlay providers, controller and websocket service

ea46ed8

feat(syncplay): integrate SyncPlay with the video player and media wr…

36441e9

…appers

feat(syncplay): add SyncPlay UI — badges, FABs, group sheet and navig…

31df136

…ation

feat(syncplay): add SyncPlay support to the native Android player

076a239

feat(syncplay): localization, web_socket_channel dependency, tests an…

3abfb94

…d docs

irican-f force-pushed the syncplay branch from 9562936 to 3abfb94 Compare June 28, 2026 13:58

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