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Thread: How render 60p project to play in slo-mo?

  1. #1
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    How render 60p project to play in slo-mo?

    Hey...
    Just bought a Canon T4i DSLR. Recorded some test footage at 1280x720/60p in native .MOV

    Objective: Play on the timeline in Slo-mo.

    I rendered the file to SpeedHQ 1280x720/30p thinking that "halving" the 60p to 30p would play back at half speed. It doesn't.

    I know that I'm not understanding the whole frame rate/shutter speed thing. What am I doing wrong?

    Thank you.

  2. #2
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    Hi Chris,

    Your query is a bit more complicated than you probably expect, but I'll see if I can break it down into stages for you.

    Issue One

    Slo-mo in SpeedEDIT

    To slow down the playback of a clip you would use the Clip Properties pane. In there, there is a button lablled "Speed" with a down arrow. Clicking on this arrow presents three choices "Speed", "Scale" and "FPS". For now keep it on "Speed".

    In the box next to it you have a percentage amount of 100. Increasing this amount speeds up the clip's playback speed, reducing it has the opposite effect.

    Performing the task
    Select the clip you want to slow down.

    In the Clip Properties pane change the speed percentage to 50. This will double the clip's duration thereby stretching the time it takes to complete playback of the clip, thereby giving the illusion of the clip playing at half speed.

    To ensure that the playback is nice and smooth, go to Control Tree > Layer Settings > Slow Motion Quality

    In the drop down menu to the right of "Slow Motion Quality" change it from "None" to "Linear". This will make your clip playback smoothly.

    And that's it. Job done.

    Issue Two

    So what was I thinking?

    Well what you did was essentially correct for Over Cranking the cameral to achieve Slow mo, but I'm thinking that when you set up your project, you either:

    • Didn't create a new project to use the reduced frame rate
    • Didn't use a codec or preset that allowed you to use your project's settings
    • Didn't create a customised preset to render using the project's settings
    • Your media player is playing back the footage at the wrong frame rate


    I've successfully used Over Cranked footage in SpeedEDIT and got it to deliver the desired slow motion, so I know it's possible.

  3. #3
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    You know what? I really appreciate the time you took to answer my question. Awesome.

    BTW, I am running Speededit in VT5. I posted here because I don't know if anyone reads the VT pages anymore.

    I have used clip properties to adjust speed in the past (it's been a few years since I've done this stuff). I remember, though, that there was discussion about VT5 not using "interpolated" frames for slow playback. Don't know if the final "update" for VT5 dealt with that issue or not. I think I read that SpeedEdit 2 will do interpolated frames. Regardless, I understood that "overcranking" and rendering to a lower frame rate was better quality than adjusting speed playback with existing files. Do you know if this is correct?

    Also, I think I'm confused about the 60p. I'm pretty sure the original properties of my footage is 720/60p and the rendered version is 720/30p.

    I'll look at the footage using the speed adjustment in Clip Properties to see if it's acceptable. I hadn't done that. Thank you, Shabazzy.

  4. #4
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    Hi Chris

    I'm always happy to offer help when I can.

    Although I can't tell you if VT5 SE update added interpolated frames, I can tell you that SE2 standalone does, and that by following my instructions in my previous post for setting the Slow Motion Quality to Linear in the Control Tree, you will activate interpolated frames.

    Regarding overcranking vs post production slow mo and the quality each produces, the answer is not really as absolute as one method is better than the other. On the issue of quality, it really all starts with the camera and camera operator. Things like the camera's lens, sensor size, codec, compression method all determine the quality of the rushes (or dailies for those in the U.S.) as well as the camera operator's understanding the camera to get the required quality. Basically, Garbage In Garbage Out.

    This doesn't let the editor off the hook though, because to produce the required results means that the software depends on; having the facility to produce slow motion, the algorithms used to produce the effect, the editor's knowledge of the software, etc.

    Then there's the chain. You may shoot and edit the footage and produce exactly what you wanted on your screen, but when you send it to the client, others will get their hands on it and by the time it ends up in the public domain, it could look awful.

    So as you see, the answer isn't quite so simple as one is better than the other.

    In my opinion, both methods can compliment each other if you know when and how much of each method to use.

    Regarding the frame rates.

    Yes, your footage would be 720/60p but to make it playback at 30fps in SpeedEDIT would mean you'd have to start a new project in 720/30p, import the footage and change the playback speed in the clip properties. If you click on the "Speed" setting and change it from Speed to FPS, this might make things a little clearer. Once it's changed to FPS, you'll see that the playback speed will be 60 fps. Change this to 30 and in the timeline the clip will be lengthened to twice as long as the original length. This is exactly what would happen with film. If you shoot a 10 second clip at 60fps, when you play it back at 60fps the clip will run for 10 seconds, however, if your camera allowed you to play that same 60fps clip at 30fps it will take 20 seconds to complete, so effectively playing 60fps at 30fps stretches the length of the clip.

    SpeedEDIT emulates that process using the Clip Properties Speed settings.

    Then when you're ready to render, you'd more than like have to customise the rendering settings by pressing the c or customise button in the render panel and checking the "Use Project Settings" box in the customise panel. From there click ok, give the render a name and watch the results once it's done.

    Depending on how it looks will determine whether you should use frame interpolation or not.

    Hope the helps,

    Shabazzy

  5. #5
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    I've had a thought about another thing you might be wondering....

    OK. That worked but I'm still not 100% clear why my way didn't.

    When you set the project to a different frame rate, it's correct that the chosen media player will (or should) play it at that rate (i.e., you've rendered out a 30fps project and Windows Media Player plays it back at 30fps). However the reason it looks the same as it did with the original clip's frame rate is because when you create a new project with SE and choose a 30fps frame rate, dragging a 60 fps clip onto the timeline will say to SpeedEDIT,

    "Hey, my frame rate is 60fps and I run for 20 seconds".

    SpeedEDIT says,

    "OK, I thanks, I can see that you're 20 seconds long, I'll do some calculations to make sure that you still run for 20 seconds at 30fps."

    Now this is quite important, because as editors, we want our editing software of choice to be as WYSIWYG as possible and when you have a mix of fps clips in the timeline you just want the editing software to concentrate on their duration as opposed to their frame rate (since as editors we're more likely to worry about duration and timing while editing) and give us a WYSIWYG preview of the project thus far. We don't want to have to manually convert clips to match the project's frame rate before we can bring them into to the timeline, so the editing software does what it does to keep the length of the source clip the same on any project regardless of the project's frame rate.

    Unless YOU tell it different. And that's where the clip properties speed settings come in.

    This is a good thing.

    Right. Hopefully I've not confused you even more, my apologies if I have.

    Shabazzy

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