Variable Frame Rate (VFR): What It Is and How to Fix It

Variable frame rate (VFR) video doesn't have a fixed number of frames per second: each frame carries its own timestamp, and the gap between frames changes during the recording. Phones, webcams and screen recorders save VFR to cope with low light or to skip frames when nothing on screen changes. It plays fine in a media player, but editors such as Premiere Pro and DaVinci Resolve are built around a constant frame rate (CFR), so a VFR file can stutter or drift out of sync with its audio. The fix is to check the file and, if it's VFR, convert it to CFR before you edit.

Below: VFR vs CFR in one table, how to spot it in MediaInfo, step-by-step conversion in HandBrake and FFmpeg, and when you can leave VFR alone. Everything was checked on 1 November 2026 against the FFmpeg and HandBrake documentation and Adobe's own FAQ. More explainers are in our video formats, codecs and numbers guides.

The short answer

Variable frame rate means the time between frames changes during the video, as it does in most phone and screen recordings. Check it in MediaInfo (Frame rate mode: Variable). If your editor drifts out of sync, convert to constant frame rate first: in HandBrake pick a frame rate and Constant Framerate; in FFmpeg run ffmpeg -i in.mp4 -fps_mode cfr -r 30 -c:v libx264 -crf 18 -c:a aac -ar 48000 out.mp4. For playback or uploading, VFR is fine.

Key takeaways

• VFR = frames arrive at uneven intervals; CFR = the same interval for the whole file.
• Adobe's FAQ names smartphones, webcams and screen recorders such as OBS Studio and NVIDIA ShadowPlay as common VFR sources.
• Premiere Pro (12.0.1 and later) shows "Variable Frame Rate Detected" in a clip's Properties and keeps audio in sync with Preserve Audio Sync, but Adobe still says converting to CFR is better before editing.
• Convert with HandBrake (Constant Framerate) or FFmpeg (-fps_mode cfr -r 30); both re-encode, so keep the original.
• Leave VFR alone if you're only watching, sharing or uploading the file: players and platforms handle it.

What is variable frame rate?

Variable frame rate is video in which the interval between frames isn't fixed. A 30 fps CFR file shows a new frame every 33.3 milliseconds from start to finish. A VFR file labelled "30 fps" might hold 33 ms gaps while you're filming in daylight, stretch to 66 ms in a dark room (an effective 15 fps, so each frame gets a longer exposure), and go back again. Screen recorders do something similar: if nothing on screen moves, they write fewer frames.

Each frame carries a timestamp, so a player shows it at the right moment and the sound stays in step. Problems start when software ignores the timestamps and assumes a fixed rate.

Which devices and apps record VFR?

Adobe's own FAQ for Premiere Pro lists smartphones, webcams and screen recording tools such as NVIDIA ShadowPlay and OBS Studio as sources of VFR media. In practice that covers most footage people bring to an editor that didn't come from a dedicated camera.

Browser recordings belong on the list too: anything made with the browser's built-in recorder timestamps frames as they arrive. That includes QuickVeed's free screen recorder and the other browser tools that save MP4 or WebM, so if one of those files misbehaves in a timeline, convert it as described below. For recording advice in general, see how to screen record.

Why does VFR make audio drift out of sync?

VFR drifts because an editor that assumes a constant frame rate places frames by counting them, not by reading their timestamps. Audio has its own fixed sample rate, so it keeps true time while the picture gradually doesn't.

A worked example: a 10-minute screen recording holds 17,700 frames because the recorder skipped some on static screens, an average of 29.5 fps. Treated as 30 fps, those frames last 17,700 ÷ 30 = 590 seconds, so by the end the picture is 10 seconds ahead of the sound. The gap grows the longer the clip runs, which is the classic sign of drift rather than a fixed delay. Audio out of sync with video covers how to tell the two apart.

Premiere Pro

Adobe's FAQ, written by Adobe staff, says Premiere Pro 12.0.1 and later detect VFR: right-click the clip, choose Properties, and look for "Variable Frame Rate Detected". For VFR clips with audio, Preserve Audio Sync is on by default (in the Effect Controls panel under the clip's MPEG Source settings) and decodes the file so the picture and sound line up. Adobe still says it's better to transcode VFR material to a constant frame rate before editing, especially for proxy, consolidate or transcode workflows, and that some files need converting anyway.

DaVinci Resolve

We found no Blackmagic documentation on VFR. Users on Blackmagic's forum report choppy playback and drift with phone and OBS files, and the fix they settle on is the same: convert to CFR first, or record at a constant rate where the recorder allows it.

How do you check if a video is VFR?

You check for VFR in MediaInfo, a free, open-source app for Windows, Mac and Linux that lists a file's technical details.

1. Install MediaInfo from MediaArea and open your video.
2. Switch to View > Text (or Tree) so every field shows.
3. Under Video, find Frame rate mode. "Variable" means VFR; MediaInfo usually also lists the minimum and maximum frame rate it found.
4. Note the frame rate it reports (for example 29.970 or 30.000). That's the rate to convert to.

If you prefer the command line, ffprobe -v error -select_streams v:0 -show_entries stream=r_frame_rate,avg_frame_rate -of default=nw=1 in.mp4 prints two rates. When they differ noticeably, the file is probably VFR; MediaInfo's wording is easier to trust.

How do you convert VFR to constant frame rate?

You convert VFR to CFR by re-encoding the video at one fixed rate: the encoder duplicates frames where there are gaps and drops extras where there are too many. Pick the rate your project uses, usually the rate MediaInfo reports (30 for most phone footage, 29.97 for a 29.97 project, 25 in PAL countries). The frame rate guide explains which to choose.

With HandBrake (free)

1. Open the file in HandBrake and pick a preset such as Fast 1080p30.
2. On the Video tab, set Framerate (FPS) to the rate you want, or Same as source.
3. Select Constant Framerate. HandBrake's presets default to Peak Framerate, which still leaves slower sections variable.
4. Raise the quality if the file is for editing (a lower RF number, such as 18), then start the encode.
5. Open the result in MediaInfo and confirm Frame rate mode: Constant.

HandBrake's documentation says Constant Frame Rate isn't recommended except in special cases, and names encoding for import into an editor (NLE) as one of them. That's exactly this case.

With FFmpeg

ffmpeg -i in.mp4 -fps_mode cfr -r 30 -c:v libx264 -crf 18 -preset medium -c:a aac -b:a 192k -ar 48000 out.mp4

FFmpeg's documentation says -fps_mode cfr duplicates and drops frames to reach exactly the requested constant rate, and -r 30 sets that rate. Use -r 30000/1001 for 29.97. -fps_mode replaced the older -vsync option, so on an old build that doesn't recognise it, use -vsync cfr instead. The -ar 48000 also fixes the other common drift cause, a 44.1 kHz track in a 48 kHz project; see 44.1 kHz vs 48 kHz.

Don't try -r with -c:v copy: FFmpeg's docs say that only relabels the stream without dropping or duplicating anything, and may produce an invalid file. Converting to CFR always means re-encoding, so the file can get bigger; keep the original.

When is variable frame rate fine?

VFR is fine whenever nothing assumes a fixed rate:

• Watching it in a player, a browser or on a phone.
• Uploading it to YouTube or social apps. They re-encode every upload anyway; YouTube's guidance is simply to upload at the frame rate you recorded.
• Short clips in an editor that already handles it, such as Premiere Pro with Preserve Audio Sync on, if the sync holds when you scrub to the end.
• Transcribing or captioning. auto subtitles in QuickVeed time each line in seconds against the audio, so you don't need to convert a file just to caption it.

Convert when the clip is long, when you're syncing it with separately recorded audio, or as soon as you see drift. Converting everything by habit costs encode time and disk space for no gain.

Frequently asked questions

What does variable frame rate mean?

The time between frames changes during the video instead of staying fixed. Each frame has its own timestamp, so players stay in sync, but editors that assume a constant rate may not.

Is variable frame rate bad?

Not for watching or uploading. It causes trouble in editing and when syncing to separate audio, where a constant frame rate is safer.

Does iPhone record variable frame rate?

Phone recordings, iPhone included, commonly show as variable in MediaInfo, especially in low light. Check the file rather than assuming.

How do I fix variable frame rate in Premiere Pro?

Make sure Preserve Audio Sync is on for the clip; if it still drifts, convert the file to constant frame rate in HandBrake or with FFmpeg and relink.

Does DaVinci Resolve support variable frame rate?

Blackmagic doesn't document VFR handling that we could find, and users report stutter and drift. Convert to CFR before importing.

Does converting to constant frame rate lower quality?

It re-encodes the video, so use a high quality setting (CRF or RF 18) and the original rate. Duplicated frames don't lose detail; the main cost is a larger file.

Try it with your own video

Recorded a demo or a talk and need captions or clips from it? Upload the recording, get subtitles you can edit, and download an SRT or captioned video. QuickVeed plans start at $18/month, and new accounts get a 14-day trial with 250 credits, no card needed. Sign up or see pricing.

Sources

Competitor details in this post were checked against these public pages in November 2026. Products and prices change, so confirm with each vendor before you decide.

• FFmpeg documentation: ffmpeg (-fps_mode, -r)
• HandBrake documentation: frame rates (VFR, CFR, PFR)
• Adobe Community (Adobe staff FAQ): how to work with VFR media in Premiere Pro
• MediaArea: MediaInfo (free, open source)
• YouTube Help: recommended upload encoding settings