Time-Lapse Video Does Not Play Smoothly

[radardetector]

I want to take a 5-minute video taken from my digital camera and use a video editing program to speed it up to 20 seconds. I have tried to do this in Windows Movie Maker and Kdenlive and the sped-up video does not play smoothly at all. However, the full 5-minute video plays just fine. I have this problem when I leave the video in .avi format as well as when I convert it to MPEG-4. What should I do?

[guns1inger]

Post a mediainfo of the source file.

There are two ways of speeding up the playback. One is to playback at a higher frame rate. This works fine on a PC, but most other players have a very fixed range of framerates.

The second is to drop enough frames that you get your required running time at a standard framerate, but this also means you will get jerky playback as you will be dropping a lot of frames.

For example, a 5 minute PAL clip has 7500 frames, playing back at 25 frames per second (fps). In order to play the same clip in 20 seconds at 25 fps you have to throw away 7000 frames, or play the clip back at 375 fps.

What do you want to play this back on ?

[jagabo]

There are two ways of speeding up the playback. One is to playback at a higher frame rate. This works fine on a PC

guns1inger knows this but for the OP: increasing the frame rate only works up to a point, even on a very fast computer. You will run out of CPU power if the frame rate is too high. How high is too high depends on the video, the codecs used, and the computer. And you won't see more frames per second than the refresh rate of your monitor. So even if your computer is fast enough to play a 240 fps video, you will only see 60 different frames per second on a 60 Hz monitor, the other 180 will be skipped.

[lowellriggsiam]

This is where programs like Sony Movie Studio, or higher end programs like Adobe After Effects come in handy.

[radardetector]

I'm using the XviD codec to compress the original AVI from my camera. Also, I have tried increasing the frame rate to 560 fps in VirtualDub, but when I try to play it in QuickTime, Windows Movie Maker, or Kdenlive, the video skips a lot. As for the refresh rate, the monitor for one of my computers has one of 61 Hz. I'm trying to edit my video on a MacBook, so is it a problem with my hardware? Also, the ultimate goal of making the time-lapse video is to upload it on YouTube, so even if it doesn't look right on my computer, could it look fine on YouTube?

[jagabo]

In VirtualDub set source frame rate to 900 (assuming the original frame rate is 30 fps), and the converted frame rate to 30. That will throw out 29 of every 30 frames and leave you with a 30 fps video that will play smoothly.

[radardetector]

So if I dropped some of the frames in VirtualDub, would I be able to speed it up in an editor to fit into 30 seconds?

[jagabo]

So if I dropped some of the frames in VirtualDub, would I be able to speed it up in an editor to fit into 30 seconds?

Yes. In the frame rate dialog set the source frame rate* to 20 times (because 30 seconds is 20 times faster than 5 minutes) the actual source frame rate, then set the converted frame rate to the actual source frame rate.

*Setting the source frame rate (at the top of the frame rate dialog box) is telling VirtualDub to ignore what the videos real frame rate is, treat it as if it is the frame rate you specify.

[Gavino]

In the frame rate dialog set the source frame rate* to 20 times (because 30 seconds is 20 times faster than 5 minutes) the actual source frame rate, then set the converted frame rate to the actual source frame rate.

You mean 10 times, don't you?

[jagabo]

In the frame rate dialog set the source frame rate* to 20 times (because 30 seconds is 20 times faster than 5 minutes) the actual source frame rate, then set the converted frame rate to the actual source frame rate.

You mean 10 times, don't you?

LOL. Yes.

So if the source video is 30 fps, set the source frame rate to 300 fps, the converted frame rate to 30 fps.

You could also set the source frame rate to 300 fps and the converted frame rate to 60 fps get a smoother result. But Youtube will convert that down to 30 fps so there's no point -- unless you want a smother version for your own use.

[Nelson37]

Depending on what the subject or action is, time-lapse video can't help but be jerky. Unless there is no motion at all, in which case a still photo is probably better.

[budwzr]

If you speed up, or slow down audio, the pitch changes. And when you try to correct the pitch, at a certain point it starts sounding weird. So I believe your five minute to twenty seconds conversion is outside the realm of possible due to this same dynamic.

I don't think you can scale something that far without serious distortion. Maybe 2:1 or 3:1, but certainly not 30:1.

[TreeTops]

Nelson37, Haven't you ever seen the time-lapse videos of flowers opening from a bud to the full flower? Those vids are not jerky but VERY smooth. So there must be a way to do time lapse vids without out the jerkiness.

[guns1inger]

Depends what you mean by jerky or smooth. If your camera is also moving, even slightly, then you will get a very jerky feel. You can hide some jerkiness by using simple X fades between frames. It also depends on how much movement occurs between frames taken, and what the subject actually is. As we have not seen any of your footage, it is impossible to say if framerate is the only problem that it has.

[edDV]

Vegas velocity profile will interpolate new frames rather than toss excess frames. This results in smooth motion but better, you have acceleration control over the full clip duration. Downside is some quality loss from the interpolation and recode.

[budwzr]

Vegas velocity profile will interpolate new frames rather than toss excess frames. This results in smooth motion but better, you have acceleration control over the full clip duration. Downside is some quality loss from the interpolation and recode.

That's interesting.

When I do time lapse, I use my GoPro and it takes a shot every two seconds, and I end up with a still image sequence that Vegas automatically stitches together as a single event.

The event has playback adjustment in the properties, and also there's the time stretcher on the timeline.

I'm curious as to how to best optimize the playback. Do you just have to play around with it? Or is there a rule of thumb?

[budwzr]

Vegas velocity profile will interpolate new frames rather than toss excess frames. This results in smooth motion but better, you have acceleration control over the full clip duration. Downside is some quality loss from the interpolation and recode.

Looks like 'Undersample Rate" in the event properties puts out faux timelapse. Velocity seems to only affect playback speed, like a time stretch, but as you say, variable.

That's what I like about Vegas, it has these simple controls that at first glance appear useless, but are so powerful if you add a little creativity to them. This undersampling produces a strobe effect too.

Anyway, the undersampling rate has its limits, so the OP would probably need to render out and do it again to really fine-tune it.

Thanks for that! Very helpful.