Audio Sync Troubleshooting

Understanding Sync

SendSpin Player synchronizes audio using three mechanisms:

1. Clock sync — A Kalman filter estimates the time offset between your device and the server
2. Buffered playback — Audio chunks are buffered and played at their designated timestamp
3. Sample correction — Small timing errors are corrected by inserting or dropping individual audio samples (within +/-4% rate)

Most sync issues are caused by factors outside the app’s control, such as audio hardware latency or network conditions.

Symptoms and Fixes

Audio Sounds Slightly Ahead or Behind Other Devices

This is usually caused by audio output latency that the app can’t detect automatically.

Fix: Adjust the Manual Sync Offset in Settings:

1. Open Settings > Audio Sync > Manual Sync Offset
2. If this device plays too early, increase the offset (positive value)
3. If this device plays too late, decrease the offset (negative value)
4. Start with 10-20ms increments
5. Test by listening alongside a reference device

Audio Sounds “Wobbly” or Pitch-Shifted

The sync correction system adjusts playback rate by up to +/-4%. If the clock sync is unstable, these corrections may be audible.

Fix:

1. Ensure a stable WiFi connection (avoid switching between WiFi and cellular)
2. Move closer to your WiFi access point
3. Avoid network-heavy activities on the same device during playback

Audio Drops or Gaps

Brief gaps in audio can occur when the buffer runs out.

Fix:

1. Check your WiFi signal strength
2. If using a remote connection, try a local connection instead
3. Disable Low Memory Mode if enabled (it reduces buffer size)
4. Close other apps that may be competing for network bandwidth

Bluetooth Delay

Bluetooth audio adds 50-200ms of latency that varies by device and codec.

Fix:

1. Use the Manual Sync Offset to compensate (try -100ms as a starting point)
2. Each Bluetooth device may need a different offset
3. For best sync accuracy, use wired audio outputs

Sync Degrades Over Time

If sync is good initially but drifts over hours:

Fix:

1. This may indicate the Kalman filter is converging on an incorrect estimate
2. Disconnect and reconnect to reset the clock sync
3. Enable Debug Logging and export logs to help diagnose the issue

Collecting Debug Data

To help diagnose sync issues:

1. Enable Debug Logging in Settings
2. Reproduce the sync issue
3. Go to Settings > Export Debug Logs
4. Share the file when filing a bug report

The debug logs include detailed sync statistics: clock offset estimates, correction amounts, buffer levels, and timing errors.