Cellphone video, windows editing, audio sync question(s)

OK, so after spending about 8 hours today trying to do something I assumed was relatively trivial, I’ve come to the point where I’m just too frustrated and confused to continue without some input from someone knowledgeable.

I took a 12 minute video of me playing the piano from my android phone, and I also made an audio recording of the same thing with another device. I simply want to sync the separate audio recording of better quality with the video (using also the audio from the video at a low level).

I downloaded 4 different free video editing programs today (including Lightroom at the high professional end, and Filmora at the beginner’s level end).

In both of those the audio from the video very quickly goes out of sync (putting aside the other separate audio for the moment). This is apparently due to the fact that the video was recorded in variable frame rate, not constant frame rate. (what’s surprising is that Filmora totally seems to market itself as being for someone who knows nothing, has some video they’ve taken on their phone, and wants to quickly do cool stuff with it).

  1. Is there no free video editor for windows that supports vfr?
  2. Is there anyway to do what I want without converting the video? (I think I saw a program called “handbrake” which I tried but my 12 min video would have taken nearly 2 hours to convert which might have worked this time but I want to see if there’s another solution before I accept this as part of the process each time. )
  3. I also see no way to change the frame rate settings on my Motorola. Is there a way to change it to cfr on my phone by default for the future?
  4. How do so many people seem to make cool edited videos that litter the youtubes so easily? Does everyone know about this frame rate issue but me?


I think all of the nonlinear video editors I have used work on the assumption that time and frames are somehow proportional.

I can’t say I’ve come across this issue though - all of the phones I have owned just output MP4 or something like it, with a constant frame rate. I see here that nearly every video container format seems to support VFR, but from experience, it seems like it’s rarely used.

Does your phone have any ‘quality’ settings for the video output? If you set it to the highest quality setting, it might not do it. What model of Motorola phone do you have and how old is it?

You have to edit with software that supports VFR. Apple FCPX (and iMovie which is free) does this, as does Adobe Premiere Pro CC since the 12.1 version in 2018:

Premiere Pro CC VFR support added: https://www.premierebro.com/blog/premiere-pro-1201-update-variable-frame-rate-and-new-features

I shot several minutes of 4k HEVC variable-frame-rate video on my iPhone XS and did editing tests on the below NLEs. In all cases there was no drift or audio sync issues, but it was only a few minutes of material:

DaVinci Resolve (free version)
iMovie 10.1.9
FCPX 10.4.3

All of the above running on a 10-core iMac Pro, macOS High Sierra 10.13.6.

This article discusses using DaVinci Resolve to sync audio and video: https://blog.frame.io/2017/05/15/sync-clips-in-davinci-resolve/

As you mentioned you can convert VFR to CFR material using Handbrake: https://www.youtube.com/watch?v=keA2Gyye-D0

A day later, I’m even more confused (and frustrated).

My phone is a Motorola G5s Plus. According to the specs here, the video is: 2160p@30fps, 1080p@60fps, 1080p@30fps (gyro-EIS). So that means, not vfr, right? (Incidentally I haven’t figured out how to change any video settings from within the camera app. )

I did let process overnight with Handbrake, and at first when I imported it into Filmora I still got the drift (though it seemed less), but then I noticed some preview render button thing which would give it smooth playback, and that actually worked.

But now I’m extremely pissed that nowhere on the articles recommending Filmora (on lists of free apps) nor nor in the app itself does it say anything about a huge, ugly, annoying watermark (seriously, it’s not small. It’s big, it’s right in the middle, it makes the video entirely unusable.) You only learn that right as you export.

I’m still confused though about why I was getting the drift in the first place if my camera is shooting in cfr?

I’ve heard of people finding that independently-recorded audio goes adrift from their video footage without VFR in the mix - just because maybe the tolerances on the audio recording equipment aren’t perfect - it might not be readily perceptible to the human ear, but audio that’s only a few percent faster playing back than it should be, will quickly be noticeable as off sync against the video - it’s very common not only to have to sync the start of the separately recorded audio, but also to correct for drift and other effects.

A common cause of out-of-sync is the confusion between video at 29.97 FPS and video at 30 FPS. (In short, if your phone took the video at 30 FPS but your editor thinks it’s at 29.97 FPS, it’ll slowly get out of sync as the video plays.)

It seems like 12 minutes would be too short to make that issue noticeable though. So I’m not sure that’s your issue.

If you’re wondering, 29.97 FPS is a quirk of the old NTSC video encoding used for over-the-air broadcasts before HDTV took over. Anything digital should definitely be using the proper 30 FPS, but a lot of video editing software is from the “old days” and might have 29.97 FPS set as the default somewhere.

(BTW, just because the phone says it’s capable of 1080p@60FPS doesn’t mean the software you used necessarily recorded at that rate. Those are just maximums. In particular, the software you used could have still used VFR as long as it never exceeded the phone’s maximum.)

Yeah. It could be drop-frame/non drop-frame related (Drop-frame is the odd 29.97 fps). I’d think most of the editors you mention would automatically convert the frame-rates of any video you ingest to whatever the project frame-rate is (a common frame-rate for all the clips in your project).

This makes things easier in several ways but it doesn’t mean your audio recordings and your video recordings will necessarily be in sync if they were recorded by two separate devices unless they were time-code locked (I’m almost positive yours weren’t because you’d know it if they were, ergo, you’d be handling this on your own—also, i doubt you could timecode-lock a cell phone video camera.

One technique is slightly compressing or expanding the length of the audio track to precisely sync with the video. It might take a professional level editor to do that… or at least to have it sound decent.

Drop frame is related but not the 29.97 rate you mention - you can shoot DF or non non DF in 29.97 or any other scaled frame rate. Drop frame proper is the dropping of every 12th frame of video except for every fourth? iteration of that (been a while since I had to recall the spec from memory)

Regardless, the issue here is twofold - your video and audio play at different rates, and they probably are drifting at a greater rate over time.

First, video used audio @ 24/48, while most typical audio recorders will default to 16/44.1. Those numbers refer to bit depth/sample rate. The first doesn’t bear much here, but the second means that the audio needs to be converted to 48k sample rate regardless of your other issues. That said, most decent video editors - certainly any pro NLE’s like FCPX, Premiere Pro, Resolve or Media Composer - will fix or offer to fix upon import.

As to the 30/29.97 DF/nonDF - again, a pro NLE (sorry, Non Linear Editor) should easily fix this. It’s likely that iMovie or Windows Movie Maker etc can as well but I don’t have any real experience with them.

If you have a pro level DAW - Logic, Pro Tools, Live, Reaper, etc - first step is to convert the audio file to the proper format, or import it into a pro NLE. If you don’t have one, Reaper offers a totally free download trial with no restrictions. Audacity is a capable freeware DAW. Pro Tools First is a free version as well. Garage Band on Mac is basically Logic’s free version.

If you really get stuck, I can sort you out come Monday fairly quickly but I’m away from the studio until then.

In a huge rush, about to leave for a week (I work in a kids overnight camp), so just a quick reply for now. Thanks for your responses and your offer to help picker. I’ll probably inquire further when I’m back.

After being frustrated with supposedly free programs that then in the end are not, I remember using windows movie maker some years ago without hassle. So I searched for that. It turns out, MS no longer supports it or allows it to be downloaded, there is a program called Windows Movie Maker which is just Filmora. So that pissed me off because again I wasted time only to find in the end they put a huge watermark on.

I found the old Windows Essentials version of Windows Movie Maker and this was actually the most useful at this moment for my needs. There was still drift but somehow less. And then when I imported the Handbrake 30FPS converted video and worked with it, the drift was even less but ever so slightly there. In the end I just muted the audio from the video and used the Tascam audio track. (Here’s the video if anyone’s curious.) It’s me playing the piano so, where normally you might not notice the drift, in this case by the end you definitely heard 2 separate noted going increasingly out of phase like an old Steve Reich piece.

When I get back I’m gonna re-read this thread and figure out how to continue.