When shooting video using a smartphone (including an iPhone) the software within the phone uses compression. And to capture a video at smaller size but with higher quality, most users prefer to compress video with VFR by default, known as variable frame rate. Small indeed, but those VFR footages taken by your iPhone, iPad, Camtasia, nVidia ShadowPlay, Panasonic GH5 and such may be problematic during the process of editing and playback in the non-linear editing tools. For example, Adobe officially supports VFR video since the 12.0.1 update in early 2018, but it still gives its users some import and audio and video out of sync issues with VFR in Premiere Pro.

For those who are getting problems with editing VFR video in NLE software like Adobe Premiere Pro, DaVinci Resolve, Sony Vegas, Avid, Final Cut Pro, etc., don't waste your time on searching and trying complex troubleshooting methods in vain, transcoding VFR video to CFR/constant frame rate is the jack-of-all-trades.

Part 1. What is Variable Frame Rate (VFR)?

Variable Frame Rate, shortly for VFR, is a term wildly used in video recording. As the name suggests, if a video is recorded in VFR mode, the camera will automatically adjust the frame rate according to what's going on in the scene.

Variable Frame Rate - VFR

Compared to CFR(constant frame rate), this efficient recording method can not only improve recording ability greatly, but also reduce the file size with the maximum FPS. These huge recording benefits make VFR shooting adopted in many places. Examples include:

• video recorded by your iPhone, iPad, Panasonic GH5, etc.
• webcams
• game-play recording software like NVIDIA ShadowPlay
• other screen capture applications like OBS Studio

Part 2. How to Detect Whether Your Source Recording Has VFR

If you use Adobe Premiere Pro (version 12.0.1 or higher), you can easily find out if a video clip is shot using VFR. After the VFR video is imported into Premiere Pro CC, its Properties will list "Variable Frame Rate Detected" text.

1. Import the media file in Premiere Pro (version 12.0.1 or higher)
2. Right click on the media file and select Properties
3. In the Properties panel, you would see Variable Frame Rate Detected if the media has VFR.

Premiere Pro - Variable Frame Rate Detected

If you don't have Adobe Premiere Pro, you can use other software to detect VFR. There's a free one called MediaInfo.

Part 3. What's the Problem with Variable Frame Rate?

Like with the h.264 or h.265 compressed video format, variable frame rate reduces file sizes at the cost of adding extra processing needs in playback and editing. Essentially, while it saves hard drive space, it's an extra drain on your system. Therefore, you can start to experience "juddering" or "lagging" when playing back the footage, especially if you add extra effects to the video.

There's no rule here. Only that the more power your system has, the more likely it will be able to handle the extra demand h.264/h.265 or VFR puts on it.

Audio sync issues - When a video file is playing back at a variable frame rate, it can cause problems with audio sync. If the audio file is playing at a consistent speed while the video is constantly changing, then you might find they move out of sync with each other.

Take Adobe Premiere Pro for an example. Old Adobe hates VFR, because VFR is really difficult to work with when synchronizing the audio. But the situation has turned around since Premiere Pro finally supports VFR in version 12.0.1. It keeps audio in sync with video automatically by adding or dropping frames using new "Preserve Audio Sync" feature (under Master Clip Effects). Yep, this framing adjustment preserves some audio sync, however, may result in a choppy-playback video too.

"Most recently, when doing screen recordings on the iPhone, and it outputs a variable framerate video. Unless I convert the videos ahead of time, premiere pro seriously chokes on the footage. Makes it extremely slow, seemingly skipping frames, etc." - a reddit post in July, 2018

Premiere Pro - Preserve Audio Sync

Part 4. How to Transcode VFR to a Constant Frame Rate Easily and Fast

Ultimately, though, the most commonly suggested fix an VFR issue is to transcode your variable frame rate footage to a constant frame rate before editing with a third-party software. There is a broad range of video transcoders out there. Among them, the easy-to-use but professional EaseFab Video Converter is highly recommended.

EaseFab Video Converter - The One-Click Solution to Fix VFR Video Editing and Playback Error:

◉ Firstly, with 400+ input codecs built in, EaseFab Video Converter works perfectly with video taken by iPhone, iPad, Android, camcorder, camera, and recording projects at any resolution, frame rate and bit rate.
◉ Secondly, the clear and interactive UI allows users, especially those green hands, to set constant frame rate value and finish the conversion in only clicks.
◉ Thirdly, it comes with own "intermediate" or "production" codecs like Apple's ProRes 422, Avid's DNxHD, Apple Intermediate Codec and other high-quality codecs, which can ensure maximum editing quality and efficiency when working with iMovie, Final Cut Pro, Avid Media Composer, Adobe Premiere, DaVinci Resolve and more. ◉ At last, if the running computer has hardware acceleration engine powered by Intel, AMD or Nvidia, the software will detect and make use of it by itself to boost video transcoding speed.

Tutorial: How to Convert Video from VFR to CFR in Clicks

In the following guide we take EaseFab Video Converter (Windows version) as an example. Mac version shares the same steps.

Step 1. Detect and input your source VFR video into EaseFab Video Converter. You can click "Add Video" button to add or by "drag and drop" method.

Load Source VFR Footage

Step 2. Click the Profile bar at the bottom. For general usage, you're recommended to choose MP4 (H264, AAC) from Common Video category since MP4 is an ideal universal format for editing, streaming and playback.

Select MP4 H.264 for Transcoding VFR to CFR

You can also choose the high-quality codecs like Apple ProRes, DNxHD codecs from Editing Software category. These codecs can generate files with best image quality and better editing performance for Adobe Premiere Pro, Final Cut Pro, iMovie, Avid, DaVinci Resolve, etc. NLEs.

Select ProRes, DNxHD for encoding VFR to CFR

Step 3. Click the "Settings" button to adjust frame rate, resolution, bit rate, and more. Navigate to Frame Rate (FPS) option under Video Options and pick a proper value according to the content. 24 fps and 30pfs are top choices for common videos.

Set Frame Rate

Step 4. Cut or crop video if necessary using EaseFab's Editing function. When everything is ready, click "Convert" button to get the conversion started.

Once the conversion completes, you can edit or play the converted VFR footage without A/V unsycned, choppy playback issues...

Final Words:

FFmpeg and HandBrake are top video transcoders in the video converting circle. Compared to EaseFab Video Converter, FFmpeg is far more complex for newbies due to the commands, and HandBrake, on one hand, has less output formats (only .mp4 and .mkv) for non-linear editing tools, on the other hand, produces fake CFR video with A/V out of sync matter is still here.

Final words for all of the video nerds: if you are bound to do post-production with your recordings, taking movie with a fixed frame rate is a wiser choice.