Network Sync

Network sync allows you to synchronize video playback across multiple computers on the same network. This is essential for large installations where a single computer can't drive all the required screens.

Overview #

Network sync uses a server/client model:

• Server: One computer acts as the master, broadcasting its playback position
• Clients: Other computers listen and sync their playback to match the server

All computers must have the same video file loaded and be connected to the same local network.

When to Use Network Sync #

Network sync is designed for scenarios where:

• You have more screens than one computer can support
• Screens are physically distant (different rooms, different floors)
• You need redundancy (multiple computers for reliability)
• Your video wall is larger than one computer's GPU can handle

Example Setups #

Retail Store

• Server in back office driving main entrance screen
• Client computers at each department driving local screens
• All showing synchronized promotional content

Event Venue

• Server at tech booth
• Clients driving screens throughout the venue
• Perfect sync for live event content

Large Video Wall

• Multiple computers, each driving a section of the wall
• One server coordinates timing
• Each computer uses Global Canvas Extension to define its position
• Appears as one seamless screen

Requirements #

Before setting up network sync:

1. Same network: All computers must be on the same local network (same subnet)
2. Same video file: Each computer must have an identical copy of the video file
3. Network ports: UDP port 9201 must be available (FloSync's default)
4. Firewall: Allow FloSync through your firewall on all computers

Setting Up the Server #

The server is the "master" that other computers sync to.

Step 1: Load Your Video #

1. Open FloSync on the computer that will be the server
2. Load your video file by dragging it onto any screen box
3. Optionally, use the timeline to seek to your desired starting position

Step 2: Start Broadcasting #

1. Click the Server icon (tower icon) in the top bar
2. The icon will turn green, indicating server mode is active
3. FloSync is now broadcasting its position to the network
4. The status bar at the bottom will show "Server"

Screenshot: FloSync running as server, showing the green tower icon in the top bar and "Server" status in the bottom status bar.

Server Behavior #

Once running as server:

• FloSync broadcasts its playback position to all connected clients
• Play/pause/seek commands are sent to all clients
• The server computer controls playback for all connected clients

Controller Mode (Server-Only Feature) #

When running as a server, you have access to Controller mode - a special Go Live option that lets you control remote displays without creating fullscreen windows on your local machine.

What it does:

• Broadcasts to network clients just like regular Go Live
• Content plays in the composer's preview boxes instead of fullscreen
• All playback controls remain active (play, pause, scrub, scene navigation)
• Status bar shows "Live (Controller)" with an orange indicator

When to use it:

• Operating a video wall from a laptop at a control booth
• Managing displays at a trade show while keeping your screen available
• Testing network sync setup without going fullscreen locally
• Running a live show where the operator needs to see and control content

How to use it:

1. Start server mode (green tower icon)
2. Load your content
3. Click the Go Live dropdown
4. Select Go Live (Controller)

Clients connected to your server will go live normally with fullscreen windows, while your server machine stays in the composer view.

See Scheduling - Controller Mode for more details.

Setting Up Clients #

Clients discover and connect to the server automatically.

Step 1: Load the Same Video #

1. Open FloSync on each client computer
2. Load the same video file that's on the server by dragging it onto a screen box
3. The filename doesn't need to match, but the content must be identical

Important: Clients must have the same video loaded. If the video length differs, sync will not work correctly.

Step 2: Connect to Server #

1. Click the Client icon (wifi icon) in the top bar
2. FloSync will start searching for servers on the network
3. A dialog appears showing discovered servers

Screenshot: The server selection dialog showing one or more discovered servers listed with computer name, IP address, and video duration.

Step 3: Select Your Server #

1. Click on the server you want to connect to
2. FloSync will connect and begin syncing
3. The client icon will turn blue, indicating connected status
4. The status bar at the bottom will show "Connected to [server name]"

Screenshot: FloSync running as client, showing the blue wifi icon in the top bar and "Connected to [ServerName]" in the bottom status bar.

Client Behavior #

Once connected:

• The client follows the server's playback position
• Play/pause commands from the server are followed
• The client checks for drift and corrects automatically
• Local playback controls are still functional but will be overridden by server

Network Sync in Action #

Once your network sync is running:

Starting Playback #

1. Press play on the server computer
2. All connected clients will start playing
3. Playback remains synchronized

Pausing #

1. Press pause on the server computer
2. All clients will pause at the same position

Seeking #

1. Scrub the timeline on the server computer
2. All clients will seek to match

Client Controls #

Clients can also control playback locally, but:

• Play/pause will affect only that client temporarily
• The next sync check will re-align the client with the server
• For best results, control playback from the server only

Persistence and Auto-Reconnect #

FloSync remembers your network sync configuration and automatically restores it when restarted.

Server Persistence #

If FloSync is running as a server when you quit:

• On next launch, it automatically starts as server again
• No manual action required
• The server icon (tower) will be green immediately

Client Auto-Reconnect #

If FloSync is connected as a client when you quit:

• On next launch, it automatically searches for the last connected server
• The client icon (wifi) turns orange during search
• Status bar shows "Searching for [server name]..."
• When the server is found, connection is re-established automatically

Server Disconnection Handling #

If the server stops, quits, or becomes unreachable while a client is connected:

• The client automatically detects the disconnection
• The client icon turns orange (searching mode)
• FloSync continues searching for the server
• When the server comes back online, the client reconnects automatically

This is useful for:

• Server restarts during configuration changes
• Brief network interruptions
• Server app crashes that are quickly resolved

Manual Server Selection #

When the client icon is orange (searching), you can click it to:

• Stop Searching - Exit client mode entirely
• Keep Waiting - Close the dialog but continue searching in the background
• Select a different server - If other servers are visible, click one to connect

Interval Mode with Network Sync #

When using Interval scheduling mode with network sync, clients automatically follow the server's scene transitions.

How It Works #

1. Server controls scenes - The server determines which interval scene is active
2. Clients follow - When the server transitions to a new scene (by timer or keyboard), clients receive the change
3. Keyboard sync - If someone presses arrow keys or number keys on the server, all clients switch to the same scene

Setup #

1. Configure the same interval schedule on server and client computers
2. Load matching content in each scene
3. Start server mode on the master computer
4. Connect clients to the server
5. Go Live on the server first, then on clients

Notes #

• Only video content syncs between computers; images and web pages display independently
• Cue scenes (manual advancement) work with network sync - press a key on the server to advance all computers
• Scene content must match between server and clients for proper sync

How Sync Works #

FloSync keeps all your computers playing together automatically. When a client drifts from the server, it corrects itself seamlessly.

Sync Tolerance #

The default network sync tolerance is 50ms - this is the maximum allowed difference between server and client before a correction happens. You can adjust this in Preferences if needed.

For most setups, you won't notice 50ms of drift - it's imperceptible to the human eye and ear.

Multi-Computer Video Walls #

For video walls spanning multiple computers, combine Network Sync with Global Canvas Extension and Spanned Mode.

How It Works #

1. Server broadcasts position - One computer acts as the master
2. All computers sync playback - Clients follow the server's timeline
3. Each computer shows its portion - Global Canvas Extension defines which part each computer displays

Setup Process #

1. On all computers: Load the same video file
2. On all computers: Set screen mode to Spanned
3. On all computers: Configure Global Canvas Extension for each computer's position in the wall
4. On the server: Click the server icon (tower) - turns green
5. On clients: Click the client icon (wifi) and connect to the server - turns blue
6. On all computers: Click Go Live

Example: 3-Computer Video Wall #

For a 3×2 wall (three computers side-by-side, each with 2 stacked 1920×1080 screens):

+-------------------+-------------------+-------------------+
| Left PC Screen 1  | Middle PC Screen 1| Right PC Screen 1 |
+-------------------+-------------------+-------------------+
| Left PC Screen 2  | Middle PC Screen 2| Right PC Screen 2 |
+-------------------+-------------------+-------------------+

Global Canvas: 5760 × 2160 pixels

Canvas Extension settings:

Visual Preview #

Use the Global Canvas Preview (zoom icon) to visualize your setup:

• Dark areas show where other computers' screens are
• Grid lines help align to screen boundaries
• Drag your local screens to adjust position
• Hold Shift while dragging for free (non-grid) positioning

Best Practices #

1. Test before the event: Always test your full setup before going live
2. Use wired networking: WiFi introduces latency and reliability issues
3. Match video files exactly: Even slight differences in encoding can cause drift
4. Start server first: Ensure the server is running before starting clients
5. Monitor the sync log: Use the log panel to watch for sync issues
6. Have a backup plan: For critical installations, have spare equipment ready
7. Go Live after connecting: When using network sync, establish the connection before going live
8. Configure canvas extension first: For multi-computer video walls, set up Global Canvas Extension on each computer before going live

Troubleshooting Network Sync #

Server Not Found #

Symptoms: Clients don't see the server in the discovery dialog

Solutions:

1. Verify both computers are on the same network/subnet
2. Check that the server has actually started (shows "Server" in status bar)
3. Temporarily disable firewalls to test
4. Verify UDP port 9201 is not blocked

Sync Drifts Over Time #

Symptoms: Clients gradually fall behind or ahead of the server

Solutions:

1. Check network quality (packet loss causes missed sync updates)
2. Reduce sync tolerance in Preferences for tighter sync
3. Verify video files are identical (different encodes may have timing differences)
4. Check CPU load - overloaded systems may struggle to maintain sync

Jerky/Stuttering Playback #

Symptoms: Video stutters or jumps frequently

Solutions:

1. Increase sync tolerance in Preferences (try 100ms)
2. Check network congestion
3. Verify hardware can handle the video decode
4. Use a wired network connection instead of WiFi

Connection Drops #

Symptoms: Client disconnects from server intermittently

Solutions:

1. Check network stability
2. Verify server is still running
3. Check for IP address conflicts
4. Consider network switch/router quality for large installations

Firewall Configuration #

FloSync uses UDP port 9201 for network sync. To allow through your firewall:

macOS: FloSync will prompt for permission on first use. If blocked, go to: System Settings > Privacy & Security > Firewall > Options > Allow FloSync

Windows:

1. Open Windows Defender Firewall
2. Click "Allow an app through firewall"
3. Add FloSync and enable for Private networks