accelerate video like in documentaries

[cd090580]

Hi,

I shot a video with my dv cam during about 15 minutes of an opening flower.

Now, I'd like to accelerate this video to have some effects like in documentaries when the whole eclosion (real time 20 minutes) if displayed in about 15-20 seconds.

Like in this video: http://www.youtube.com/v/9SE-EAV5NS0

Do I just need to use some selection of frames (acceleration of 5x, select every 5th frame ????) or is there any software to do it.

I'd like to do this effect with either vdub or avisynth. PS: I don't need the sound.

Thanks.

[guns1inger]

Shots like that are usually done using timelapse, so the camera is shooting perhaps 1 frame per second. When the video is played back at 24, 25 or 29.97 fps, you get the effect of time speeding up.

You can probably do it in avisynth with something like

SelectEvery(25,0)

This will select every 25th frame, or 1 frame per second of PAL footage.

[filmboss80]

You are referring to timelapse photography. Usually, it is done during the recording process, with one frame being recorded per 10 seconds or whatever. However, in your case, most payware video editing programs will allow you to speed up the footage. I've never tried with VirtualDub or Avisynth, so I don't know if they offer very efficient options for what you want to do. Theoretically, I suppose you could select every few frames, but I think you'll work like a dog that way. It wouldn't hurt to search for a VDub filter before looking into a payware editor. But if this is a onetime thing, get a demo version of Premeire or Vegas or whatever, to see if you can speed up the clip that way. (I always think you should try the free and easy route as a first option. If that doesn't work, well...)

Addendum: Aaa! Once again, Gunslinger answers the question, just as I am in the process typing in this response.

[guns1inger]

Vegas' Velocity Envelope would make short work of this, but it is a large download and an expensive purchase for a single short effect. If oyu have access to Vegas, give it a try.

[cd090580]

Thanks. I'll try with avisynth

[GTRBudda]

ImageGrab can do this also.

[cd090580]

Shots like that are usually done using timelapse, so the camera is shooting perhaps 1 frame per second. When the video is played back at 24, 25 or 29.97 fps, you get the effect of time speeding up.

You can probably do it in avisynth with something like

SelectEvery(25,0)

This will select every 25th frame, or 1 frame per second of PAL footage.

I tried on a 5 minutes video. In virtualdub, it shows 299 frames when I load the avisynth script but after encoding the new video is still 5 minutes. It seems it select 1 frame every 25 frames and then duplicate 25 times the selected frame, so the video is not accelerated but just like a slide show made of 1 seconds stills.

Am I missing something ???

[manono]

Am I missing something ???

Yeah. While SelectEvery(25,0) does, indeed, play every 25th frame, it also slows the framerate to 1fps (if it was 25fps to begin with). As you would have discovered had you checked. To then get it speeded up:

SelectEvery(25,0)
AssumeFPS(25)

[dun4cheap]

Many of your popular video editing tools can do timewarps. Pinnacle Studio and Liquid can without any problems.

You can speed it up or slow it down.

[cd090580]

I'll try with assumeFPS(25).

I don't have any commercial editor. I only have free tools (virtualdub and avisynth), then I do my encoding.

[jagabo]

You can do the same as manono's AviSynth script with only VirtualDub. In VirtualDub select Video -> Frame Rate. In the top section of the Frame Rate dialog enable "Change frame rate to fps" and set the value to 25 times the actual source frame rate (625 assuming your source is 25 fps). Then in the middle section select "Convert to FPS" and set the frame rate to 25.

[JohnnyMalaria]

You can use our Enosoft DV Processor to do it for free and very easily (it has a specific timelapse function where you specify one frame every xxx frames).