CineSync answers one question fast — does this audio line up with this picture? — and hands you a marked cue sheet for the edit. It is a timing check, not an editor. Everything runs in your browser; no file ever uploads.
You generated your shot in Runway, Kling, or Veo, your music in Suno or Music Maker, and your voice in ElevenLabs — three separate tools. Before you import everything into Premiere or Resolve and commit to a render, CineSync lets you confirm the beat lands on the cut, the VO fits the shot, and nothing runs long. The output is a list of timestamps you (or your editor) drop straight onto the NLE timeline.
Drag a video into Picture (.mp4 / .mov / .webm) and an audio file into Sound (.mp3 / .wav / .m4a). Picture also accepts an audio file — drop two audio files to check music against voice.
Both sources sit on one time axis: Lane A is the picture's audio, Lane B is the sound track. Click anywhere to seek, press Space to play, and listen for where things land.
If the track is early or late, nudge the Sync offset slider (or the ±10 ms buttons) until it locks. Positive delays the sound; negative pulls it earlier.
Park the playhead on a beat hit, dialogue cue, or cut point and press M. Pick a type and add a short note. Drag any flag to fine-tune it.
Name the project and export a .md cue sheet for your editor, or a .json session you can re-import later to pick up where you left off.
| Key / control | What it does |
|---|---|
| Space | Play / pause |
| M | Add a marker at the playhead |
| ← / → | Nudge the playhead 0.1 s (hold Shift for 1 s) |
| Click timeline | Seek to that point · click-drag to scrub |
| Drag a flag | Reposition that marker on the timeline |
| 🔊 Picture / Sound | Mute either source to isolate the other while checking sync |
| Type | Use it for |
|---|---|
| Beat | Musical downbeats and kicks you want a cut or action to land on |
| Dialogue | A line start or VO cue that has to sit under a specific frame |
| Cut | Where you intend to cut to the next shot |
| SFX | A foley or sound-effect hit that must align to an on-screen event |
| Custom | Anything else — transitions, notes, reminders for the editor |
| Format | Best for |
|---|---|
.md timing sheet | Hand to an editor or paste into CineBible — readable lines like 00:04.20 · Beat · "kick — cut here" |
.json session | Re-import into CineSync to restore markers, offset, and project name and keep working |
Lane A shows "no audio in this source." Your video has no audio track, or the browser couldn't decode it. The video still plays and drives the timeline — you just won't see its waveform. Use Lane B (your Sound track) as the reference.
Mute one side to hear the other. When a video already carries dialogue and you're layering music, mute Picture to judge the music alone, then un-mute to hear them together.
It's a check, not a conform. Browser playback is good enough to judge alignment and place cue markers — final, frame-accurate sync still happens in your NLE. The deliverable here is the marker list.
Nothing leaves your machine. Files are read locally and never uploaded. Close the tab and they're gone — export the .json if you want to keep a session.