How to sync videos

[Victor Engel]

I'm using Adobe Premiere for Mac to combine videos. It seems the actual frame rate is significantly different between the two. One is recorded with a security camera. The other is recorded with a camera designed to be used inside a birdhouse. For testing, since I wasn't able to sync them by moving them relative to each other in the timeline, I synced at the start using the timestamp. The clocks on the two cameras are likely not exactly in sync with each other, but the timestamp serves the purpose of this test.


Start of test - clips within a second of each other


End of test - clips out of sync by several seconds

23:11:16 vs. 23:11:16

23:28:18 vs. 23:28:10

Elapsed times:
17:02 vs. 16:54 1022 v 1014











--
Victor Engel

 

[Sean Nelson]

I use Resolve, not Premiere, but here's the general way that I'd approach this:

- Drag both videos onto different tracks on the timeline

- Use transform controls to size and move one video the the left and the other to right so that you can see both of them at the same time.

- Find two events near the start and end of both videos that you know to have occurred at the same time

- Trim the start of both videos to their respective start events (these are not necessarily at the same point on the timeline because you haven't done anything to synchronise them yet).

- Drag one video so that it starts at the same point as the other. In most editors the clip you're dragging will "snap" to the same start point as the other video. This synchronizes the start points of both videos.

- Locate the end events in both videos and trim both videos to those points (again, this will likely be at different points in the timeline).

Now it's a matter of adjusting the speed of one of the videos so that it's the same length as the other. How you do this depends on what controls your editor has - in some editors you can just put the clip into a "time stretch" mode and drag the end to match the other clip. In other editors you may need to apply a speed factor such as 1.002 or 0.996 to one clip and use a bit of trial and error to match its end points with that of the other video. Dividing one clip's duration by the other will give you a factor that should get you pretty close on the first try.

Once you've done this, you can adjust the start and end points of both clips to include more or less as needed, and also remove or change the transform controls to restore the images to fill the frame.

If you don't have specific events to key on and you trust the clocks on both videos, you can choose specific times near the start and end of the videos as your "events".

 

[Victor Engel]

I use Resolve, not Premiere, but here's the general way that I'd approach this:

- Drag both videos onto different tracks on the timeline

- Use transform controls to size and move one video the the left and the other to right so that you can see both of them at the same time.

- Find two events near the start and end of both videos that you know to have occurred at the same time

- Trim the start of both videos to their respective start events (these are not necessarily at the same point on the timeline because you haven't done anything to synchronise them yet).

- Drag one video so that it starts at the same point as the other. In most editors the clip you're dragging will "snap" to the same start point as the other video. This synchronizes the start points of both videos.

- Locate the end events in both videos and trim both videos to those points (again, this will likely be at different points in the timeline).

Now it's a matter of adjusting the speed of one of the videos so that it's the same length as the other. How you do this depends on what controls your editor has - in some editors you can just put the clip into a "time stretch" mode and drag the end to match the other clip. In other editors you may need to apply a speed factor such as 1.002 or 0.996 to one clip and use a bit of trial and error to match its end points with that of the other video. Dividing one clip's duration by the other will give you a factor that should get you pretty close on the first try.

Once you've done this, you can adjust the start and end points of both clips to include more or less as needed, and also remove or change the transform controls to restore the images to fill the frame.

If you don't have specific events to key on and you trust the clocks on both videos, you can choose specific times near the start and end of the videos as your "events".

I tried something similar to this, but I can't get it to work. Premiere has a feature where you can set a frame rate, but it seems to snap to certain values. Here's what it looks like when first opening the setting.





Here I've set it to 8 fps.





Note the duration stayed the same. It stayed the same also when I changed added small values, like 8.1, until I set it to 8.5.





Now there's a big jump in the duration.

Durations in between, which is what I want, doesn't seem possible. I tried using a tool to transcode both clips to 60 fps, and that synced a bit better but still drifted a bit. Also, there's a big jump in frame rate, so the resulting file was much larger. I think the security camera can be set to 8 fps. I tried that just now and will check the recordings tomorrow. If that works, that will suit my need. The internal camera doesn't seem to have this same flexibility. Maybe the security camera doesn't either even though it has the control in the interface. I'll find out tomorrow.

--
Victor Engel

 

[Victor Engel]

Oh, I think I found something else that might work.



Edit: yeah, this gets me what I need. I'll probably edit the duration instead of percentage, though.

--
Victor Engel

 

[Victor Engel]

Not perfect, but I don't think the clips are even consistent with themselves. Anyway, I figured out a solution to my query. For what it's worth here is the result.

Sometimes one clip is ahead of the other. Sometimes it's the other way around. If I wanted to do more tweaking, I'd split the clips up for finer adjustments, or simply edit it with a few selected short clips, which would probably be better anyway.

 

[Victor Engel]

Maybe the security camera doesn't either even though it has the control in the interface. I'll find out tomorrow.

What I found out is that I switched the camera to daylight mode, so I got a very dark video lit only by the moon. Oops. I have to wait until dark to adjust the camera, though, because, although I can switch it to IR during the day, the focus will be off since the visible light will overwhelm the IR and the camera focuses on the visible light. The camera has an autofocus feature, but it's extremely annoying, focusing randomly, in the process racking out of focus before going back into focus. For my purposes, I just set focus and leave it.