What is variable frame rate (VFR)?

VFR is when each frame has its own timestamp instead of being evenly spaced. Screen recorders, phones, OBS, and many capture cards record VFR by default — it saves space when nothing is moving. Editors expect constant frame rate (CFR) and get confused by VFR.

Why does my video have audio sync problems in Premiere?

Almost always VFR. Premiere assumes constant framerate and lines audio up to that timeline. If the source is VFR, audio drifts a few seconds out by the end of a long clip. Converting to CFR fixes it.

Will I lose quality converting VFR to CFR?

Visually, no. The conversion duplicates or drops a few frames to keep timing constant. Audio is bit-identical. Most viewers won't notice.

VFR to CFR — fix variable framerate for editors

Screen recordings, OBS captures, phone video and webcam files are often variable framerate. Premiere and Resolve hate this. Drop the file here to convert to constant framerate. No upload.

drop a VFR video here

or click to choose

What is VFR, and why does it break editors?

Most video formats store frames with timestamps. Constant framerate (CFR) puts those frames at perfectly even intervals: 30 fps means exactly 33.33 ms between each frame. Variable framerate (VFR) lets each frame land wherever — some frames are 33 ms apart, some are 50, some are 8.

VFR exists for good reasons: when you're recording a desktop screen and nothing changes for half a second, the recorder doesn't bother encoding new frames. Compressed file size goes down.

The problem: editors assume CFR. When Premiere imports a VFR file, it picks an average framerate and lines all the frames up on a CFR timeline. The mismatch accumulates — by the end of a 10-minute clip, video and audio can be 2–3 seconds out of sync.

Where VFR comes from

iPhone / Android screen recordings — almost always VFR.
OBS Studio — VFR is the default; you can switch to CFR in settings.
Game capture cards — many capture cards output VFR.
Webcams — Logitech webcams drop to VFR in low light.
Phone video — iPhones and Pixels often record subtle VFR even for normal video.
Slow-mo phone clips — almost always VFR with embedded slow segments.

How we convert it

FFmpeg's -fps_mode cfr (the modern replacement for -vsync 1) forces a constant framerate. The encoder duplicates frames where the source had gaps and drops them where the source had bursts. Audio passes through bit-identical.

Pick the target framerate to match your editor's project. 30 fps for most projects, 60 fps for gaming, 24 fps for cinematic, 25/29.97/50 for broadcast.

Quick sanity check — do I have VFR?

Open the file in MediaInfo. Look at the video stream. If "Frame rate mode" says "Variable", you have VFR. If it says "Constant", you don't — and your import problem is something else.

Privacy

VFR mostly affects screen recordings — demo videos, tutorials, internal walkthroughs, NDA workflows. Uploading them to a converter exposes them. Here, everything happens in your tab.

FAQ

Will the output be exactly the framerate I picked?

Yes. Constant framerate, no drift.

What if my VFR source is 30+ fps but bursts to 60 sometimes?

Pick 60 fps as the target to keep the high-motion segments smooth. Frame duplication at low-motion sections is imperceptible. Picking 30 would drop those burst frames — visible only on motion-heavy clips.

Does this fix the audio sync issue in Premiere?

Yes, that's the most common reason people convert VFR to CFR. The drift disappears once the timeline matches the source's frame timing.

I'm in DaVinci Resolve. Will this help?

Yes. Resolve specifically warns about VFR files in Project Settings. CFR fixes it.

Does the file get uploaded anywhere?

No. FFmpeg runs in your browser. Disconnect to verify.