How to match different frame rates on audio and video

[Petri Storlopare]

If I want to shoot video in 50p but my field recorder can't go that high (Zoom F8), what would be the easiest way to have both in sync when editing?

[Tom Roper]

There are no "frames" in audio. Set timecode to time of day on both devices.

[Petri Storlopare]

I have a Sony recorder that always slowly drifts out of sync, except if I match it with a 24fps video.
In the Zoom F8, I can choose different frame rates for internal timecode.

[Rick Reineke]

"There are no "frames" in audio. Set timecode to time of day on both devices.'
I concur
BTW, ALL devices will drift out-of-sync over time, how soon varies from one device to the next. To stay frame accurate, some kind of gen-lock is needed.

[Petri Storlopare]

What's the reason then to choose a frame rate for the timecode?

[Petri Storlopare]

I had to do a little research but I think I finally got it. Thank you for your help and suggestions!

If anybody else is wondering about these, very basic questions I suppose, then this page could be helpful: https://blog.frame.io/2017/07/17/tim...d-frame-rates/

[David Peterson]

Originally Posted by Petri Storlopare

I have a Sony recorder that always slowly drifts out of sync, except if I match it with a 24fps video.
In the Zoom F8, I can choose different frame rates for internal timecode.

Which Sony recorder? If it doesn't have a timecode generator then it will naturally drift significantly.

Originally Posted by Rick Reineke

"There are no "frames" in audio. Set timecode to time of day on both devices.'
I concur
BTW, ALL devices will drift out-of-sync over time, how soon varies from one device to the next. To stay frame accurate, some kind of gen-lock is needed.

Timecode puts the correct timestamp at the start of the file. After that you're in the untrustworthy hands of the camera! Which is ok ish enough for short takes.

Thus the purpose of genlock, which is meant to take over the camera and tell it exactly when to open the shutter for each and every moment so that over longer takes there is no drift caused by the camera.

[Petri Storlopare]

Originally Posted by David Peterson

Which Sony recorder? If it doesn't have a timecode generator then it will naturally drift significantly.

Sony PCM-D50.

[David Peterson]

Oh right, the little handheld one, yeah I wouldn't count on it keeping accurate time.

And certainly it has no means by which to match timecode with the camera.

I'd suggest checking out the Zoom F4

[Richard Crowley]

There are no "frame rates" for audio. (And no "sample rates" for video).

Audio sample rates are thousands of times higher than frame rates.
Frame rates might be 24 or 25 or 30 or even 60 or 120 frames per second.
While audio sample rates for video are most likely 48000 samples per second regardless of video frame rate.

Even professional production gear that costs more than your car cannot be relied on to hold sync by itself.
If you get common consumer (or "pro-sumer") gear to hold sync without drift for more than a few minutes you are very lucky.
The professional solution to this is to use "genlock" to hard-wire a synchronization signal between the camera(s) and the audio recorder(s). But only high-end professional gear supports genlock.

Coordinating video and audio recording is typically accomplished using timecode which is different and independent from genlock.

It is unlikely that you will have shots that last longer than the drift between audio/video. Every time you make a transition in post-production editing is an opportunity to "pull-up" the sync between audio and video. It is easier to do than it is to explain.

But if you have a very long shot where the sync drifts too far, leave the audio track alone and "shrink" or "stretch" the video track to match the audio. It will be rare for the average viewer to notice a frame gained or dropped. But you run a much higher risk of causing very audible artifacts in the audio track if you try to "stretch" or "shrink" the audio track. However, better algorithms in newer software may be able to make small changes to audio tracks without terrible artifacts.

[Petri Storlopare]

Originally Posted by David Peterson

I'd suggest checking out the Zoom F4

I just bought the F8. When reading the instruction manual I saw that it is possible to choose frame rates, and that's what initiated the question.

[Petri Storlopare]

Originally Posted by Richard Crowley

Every time you make a transition in post-production editing is an opportunity to "pull-up" the sync between audio and video. It is easier to do than it is to explain.

That's what I do all the time. I thought it would maybe be different from now on, if I choose the right frame rate on the recorder.

[Richard Crowley]

Originally Posted by Petri Storlopare

That's what I do all the time. I thought it would maybe be different from now on, if I choose the right frame rate on the recorder.

No. Alas, the problem of "drift" is not really related to frame-rate or sample-rate.
Certainly, misunderstand picture frame-rate or audio sample-rate will cause sync problems, but typically on a much larger scale than the slight "drift" we see from lack of genlock in modern gear.

Back almost 100 years ago, big movie studios distributed special power (in some cases 3-phase) that all the camera motors would operate from. The same power was used to operate the sound recorders so that everything stayed in sync (back before electronic genlock).

In many cases we still use the protocol where the director (or AD) calls "camera" and both the camera operator and the sound recordist are expected to reply: "speed!" to confirm that the camera (and sound recorder) have reached stable speed (and locked to whatever reference) and the director is then ready to call for: "slate" and then "action". A hold-over from early days when everything ran from "house sync" power.

I ran audio (and location engineering) on a 5-camera production where each of the cameras was running "iso" (only recording on their own media). The camera/shot selection was all done in post-production editing. t the beginning of each segment, I was the only one back in "master-control" (or "video village") running audio. So when the director called for camera start, it was my responsibility to watch the five video feeds (one from each camera) and my audio recorders and confirm "speed-all" when all five cameras and the two audio recorders were all started successfully. At which point we did a handclap sync and slate and the segment was off and running.

https://www.facebook.com/davidassche...rHpeeGL2nWBCkQ

[David Peterson]

Originally Posted by Richard Crowley

In many cases we still use the protocol where the director (or AD) calls "camera" and both the camera operator and the sound recordist are expected to reply: "speed!" to confirm that the camera (and sound recorder) have reached stable speed (and locked to whatever reference) and the director is then ready to call for: "slate" and then "action". A hold-over from early days when everything ran from "house sync" power.

Yup, we still call "speed" today!

In fact because I say "Sound Speed!" hundreds (thousands?) of times a year, that is why I chose to call my youtube channel that!

https://www.youtube.com/c/SoundSpeeding