How do you create Speed Ramping

Hi
I was wondering weather someone could explain to me how to creat a good speed ramping effect. For example havng a shot of someone walking at normal speed then creating the speed ramp effect and ake the speed of the shot increase or decrease as you desire? If someone could teach me how i would be very greatfull.
thanks
Josh

Comments

  • AxelWilkinsonAxelWilkinson Staff Administrator, Imerge Beta Tester, HitFilm Beta Tester Posts: 5,242 Staff
    edited March 2012
    Add a Speed effect to the footage, then keyframe the values as needed to hit the speeds you need. 0 is no movement at all, 1.00 is normal speed, and -1.00 is backward at normal speed. Once you have the keyframes, you can adjust the interpolation method of the keyframes to smooth things out further, if need be.
    So for your example, have the value set to 1.00 through the normal speed walking part, then at the pont where you want maximum speed, create a new keyframe, perhaps at 4.00 or 10.00, or whatever speed you need. Then right-click the first keyframe and set the interpolation to smooth.
  • StylaphoneStylaphone Website User Posts: 22
    Thank you very much.
    I have put your instructions into practice and it has work like you said but it has be come very bitty, as if just images being shown rather than smooth footage. Is this because of the frames per second the footage was filmed in?
    THank you for your reply and help.
    Josh
  • AxelWilkinsonAxelWilkinson Staff Administrator, Imerge Beta Tester, HitFilm Beta Tester Posts: 5,242 Staff
    edited April 2012
    Well, with any footage there will be a limit to how much you can slow it down, at which point each frame lasts so long that you see the individual images. The proper way to create real slow-motion and time ramping effects is to use a variable frame rate camera, so that when you need to slow something down you can capture it at 120 frames per second, or whatever rate you require.
    There are programs out there which can create interpolated frames to increase the frame rate, for smoother slow motion, but how well they work depends hugely on the content of the footage. Twixtor is a popular option, and there is another one which is free, and hopefully budwzr will pop in and recommend shortly. I've not used it personally, but I recall he is a fan of it, and has mentioned it elsewhere on these forums.
  • StylaphoneStylaphone Website User Posts: 22
    Thank you very much for you help Axel.
    One last thing if you dont mind. If you wanted something to speed up and still run smoothly what frame rate would you recommend. ?
    Josh.
  • AxelWilkinsonAxelWilkinson Staff Administrator, Imerge Beta Tester, HitFilm Beta Tester Posts: 5,242 Staff
    It depends on the framerate of the original, but in general, an actual framerate of about 12 fps is the lowest you can possibly go, and in some casses even that it soo low. So if your original footage is 29.79 FPS, for example, then you can slow it to around 35% at most. One trick to getting even slower results, if you camera has the ability, is to capture the footage at 60 FPS (Canon DSLR's can do this, at 1280x720), then after importing it into Hitfilm, change the Properties of the footage to 29.97, and the footage will play back at half speed, but without any duplicate frames. You could then set the speed of that footage to 50%, and you get quarter speed playback, with a framerate of 15 FPS, which is usually acceptable. When using this technique, though, make sure to set the shutter speed of your camera to 1/125, rather than 1/60, so the amount of motion blur feels right.
  • budwzrbudwzr Website User Posts: 655
    edited April 2012
    Yeah, what you want to do is called "Velocity" in Vegas Pro. Not sure about HF. But like Axel said, you need a high enough base framerate so when the slomo starts it doesn't judder.
    Anyway, this software here: http://www.spirton.com/convert-videos-to-60fps/ is free, and I use it myself, and it works very well. But you do need to follow the setup procedure.
    Once it's set up, you're all automatic.
    I have personally processed a 30p to 60p to 120p project and the 60p file was great, but the 120p was so-so, but still usable in a pinch or with some FX added. FX cover a multitude of sins. <Hot Tip>.
    This video demonstrates the undercrank process using just an NLE with no frame interpolation. It's full of judder :

    This one has been run through the free software, and interpolated to 60p. Notice at half speed (slomo) it's smooth. Whatever judder you see was from the original stinkass Panasonic nogoodbasterd camera, but that's another story.
    The first half is 30p, and the second half is interpolated 60p playing at 30p.

    Anyway, if you want to speed ramp, like stop/go slomo, you need to double the framerate to get smooth halfspeed playback. And do not "blend" the fields. Blending kills the effect. IOW, if you want to go down to 15fps, playing back at 30fps, you need to start off with 60fps.
    That's step one!
    Then, you need to keyframe the speed changes in HF, but that should be pretty straightforward. The easy part.
    This video has keyframing:

    Now here's the deal, If you want a very dramatic extreme effect, like what you might see on a TV commercial, you have to make two or three files. It's a little hard to explain, but the slower you go, the more frames you need, but your files will all be normal speed, like 30p.
    But WITHIN those normal files the footage will be undercranked. Does that make sense? Maybe someone else can clarify, hahaha, I know it's confusing, and sounds like a lot of work, but it's really not that bad.
    The thing is, if you go super extreme, one file doesn't have enough temporal range. Like this one. Notice the blurring during slowdown, but still not too bad.
  • budwzrbudwzr Website User Posts: 655
    edited April 2012
    If you wanted something to speed up and still run smoothly what frame rate would you recommend. ?
    The frame rate will always be the project settings. The actual frame rate doesn't change. It's the playback rate that changes WITHIN the context of the actual framerate.
    You playback 15,30,60,120, or whatever fps inside a normal 30p file. It's called over/under cranking. You're "filming within a film", hahaha.
    The video "Speed Changes" up above is a standard YouTube 30p file.
  • AxelWilkinsonAxelWilkinson Staff Administrator, Imerge Beta Tester, HitFilm Beta Tester Posts: 5,242 Staff
    Keep in mind that the frame rate of the project, which controls the number of frames that play back per second on the timeline, and the frame rate of each individual video clip, which control how many of its frames will play back per second, are two separate settings, but both are labeled as "Frame Rate" within HitFilm, in the properties of the timeline/media clip respectively. So if you import a 60p clip, then right-click that clip in the Media panel and select Properties, you can change its Frame Rate to 30 FPS, and as a result the clip will play back at half speed when you add it to a 30 fps timeline.
    Overcranking originates fromt he time when you actually had to turn a crank to drive the film through the camera while capturing your footage, and to capture more frames er second, you had to crank faster, or overcrank the camera. Of course, in film cameras that is all controlled by motors now, but the process remains the same; in order to get something to play back in slow motion, you need to create more frames per second, so it can play back slowly.
  • budwzrbudwzr Website User Posts: 655
    edited April 2012
    Yeah, and the tricky part is avoiding blends. So if you stick to speed multiples of 1/2, I think HF can avoid blending. Not too sure on that though.
  • StylaphoneStylaphone Website User Posts: 22
    Well thank you very much the both of you i will try out bth your techniques and hopefully get the effect i need.
    THank you very much
    Josh
  • StylaphoneStylaphone Website User Posts: 22

    and as a result the clip will play back at half speed when you add it to a 30 fps timeline.
    How do you change the properties of the timeline so that it is playing at 30fps?
  • AxelWilkinsonAxelWilkinson Staff Administrator, Imerge Beta Tester, HitFilm Beta Tester Posts: 5,242 Staff
    Well, if its the Editor timeline, then it is set up in the main Project screen. If the timeline is a composite shot, then it has its own properties, which can be accessed either via the media panel, or through the "Properties" button at the top right corner of the timeline panel.
  • budwzrbudwzr Website User Posts: 655
    Also, note that 50/60 interlaced footage is really 25/30 progressive that's been frame split to comply with broadcast standards.
    So it's NOT a high enough framerate to do slomo, although the numbers appear to be good. Remember, you need at least 60p to go down to 15fps.
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