Set up, calibrate
and export.

Getting started

1. Select an H.264 MP4 or MOV with one audio track, up to two hours long.
2. Align sound and picture in the start clip, then the end clip. Use a clear word, clap or visible impact.
3. Check all three preview clips. If the middle is still wrong while both ends are correct, the drift may not be linear.
4. Export the first five minutes for free, or use an activated license for a full export. Keep your original file.

A file extension alone does not guarantee support. HEVC video, multiple audio tracks, damaged files and sudden timing jumps are outside this version's scope.

Calibration and replay

Use the slider or 10 ms buttons to align the audio. Choose a different clip position if the current clip does not contain a clear sync point.

Replay after adjustment jumps back within the current calibration clip. Set the replay distance from 0.5 to 10 seconds, or switch it off. Near the beginning of a clip, the replay stops at that clip's start instead of seeking outside it.

Save your work as a calibration project to return later. A project refers to the original video; it does not embed or upload the footage. Keep the original file available.

Licenses and credits

Activation happens in the desktop app, not on this website. Open the license button in the app header to activate a code or add another server-issued export code. In server mode, one profile can hold multiple export codes. Their remaining credits are combined; entering the same code again does not add credits. An active Personal license takes priority and does not spend your export credits.

Personal · $9.99 one-time

Planned access to unlimited full exports for SyncMend 1.x, up to two devices. No subscription. Full exports currently require a live server check.

Single export · $0.50

Planned one-credit purchase. One successful full export uses one credit. Zero credits means no full exports remain; it never means unlimited.

Activate license

Checks the pasted key and registers this device. Server-issued keys begin with DFXS-. Local DFX1- test keys and server-issued keys are not interchangeable. This dialog only handles activation; maintenance controls are in Settings.

Refresh status

In Settings, fetches the latest plan, combined remaining credits and activated device count. It does not itself add credits. Refresh after an owner-approved top-up; activate a new code to redeem a separate export entitlement.

Retry credit confirmation

Shown in Settings only when a completion or cancellation needs confirmation after a connection problem. It does not create a new purchase, add credits or automatically resolve an unknown outcome.

Copy device ID

In Settings, copies the random identifier for this application profile, useful for support. It is not your license key.

Deactivate this device

Shown in Settings for Personal. Releases this device's Personal activation, provided no export is pending. Export codes and their remaining credits stay on this profile. Credit licenses cannot be transferred by the client.

Support details

Expand this section in Settings to see the current mode and licensing address. A 127.0.0.1 address is a local test server, not a public service. A production build must use an HTTPS licensing domain.

Always check the number of full exports remaining. Zero means no paid full exports remain, not unlimited access. Displayed status can be cached; the server is authoritative at full export time. Free five-minute exports remain available.

If an export is interrupted

Do not repeatedly export, delete license data or manually remove recovery files. First check whether the output video already exists.

• If the app reports that completion could not be confirmed, keep the generated video and use Retry credit confirmation once the server is reachable.
• If the outcome is unknown after a crash, owner review is required. A reserved credit is not automatically refunded, because the export might already have succeeded.
• A failed or cancelled export normally returns its reserved credit after cancellation is confirmed.

Troubleshooting

E_LICENSE_NETWORK

The licensing server could not be reached. Check connectivity and try Refresh status. Free previews and five-minute exports do not require a paid authorization.

E_CREDIT_REQUIRED

No full export credits remain on this profile. Activate a new server-issued export code, or refresh after an owner-approved top-up.

E_LICENSE_PENDING / E_LICENSE_BUSY

An export or recovery record is still open. Do not delete the profile to bypass it. Stop the exporting client and request owner review.

E_LICENSE_FINALIZE

The video may have been generated but its credit confirmation failed. Preserve the output and retry confirmation.

E_LICENSE_REJECTED

Check that the key matches the app's licensing mode, then check its device limit and revocation status. A previously redeemed export code does not add credits again. Keep the exact error message for support.

For a black playback screen, verify the input format and try loading the calibration clip again. Do not export until you can confirm both sync points.

Support and privacy

Contact Jessica at mk@syncmend.com, or visit our contact page. Include the app version, error code and device ID if relevant. Do not send license secrets or private footage unless you explicitly choose to share a sample.

Legal pages are drafts and must be completed before public release. See the privacy draft, refund draft and third-party notices.