Slow motion video app wanted

Discussion in 'iOS Apps' started by TwoBytes, Jun 20, 2011.

  1. TwoBytes macrumors 68030


    Jun 2, 2008
    Some cameras can take double the fps and slow it down to create a very smooth slow motion video effect (no frammes dropped..)

    is there an iphone app to do this?

    Sort of like these examples
  2. psonice macrumors 6502a

    Jul 22, 2005
    Not really possible. For true slow motion you need something like this:

    - Camera records 300 frames per second
    - Play back at 30 frames per second

    That gives you 1/10th speed playback

    The iPhone camera can do up to 30fps recording. For smooth playback, you need 30fps. I.e. you can't slow it down.

    You COULD play back at 15 fps, which isn't quite smooth but it's acceptable. That would give you 1/2 speed. So a bit slower, and ok smoothness.

    Or, you can use 'motion estimation' techniques, which let you fake the extra frames. This would give you as much slowdown as you want, and smooth playback. But, it's faked, and sometimes the 'extra' video frames don't come out quite right. So it's glitchy. And it would take quite a while to draw the extra frames, especially on a phone. Plus anything too fast for the camera won't get caught in the first place, so you couldn't record anything really fast moving anyway.
  3. TwoBytes thread starter macrumors 68030


    Jun 2, 2008
    Thanks for the technical explanation!

    I'm hoping for an all that will allow for higher fps recording or even playback at 15 as you say.

    I've searched and nothing is on the app store..

    Maybe an area for growth!
  4. mroddjob macrumors member

    Jun 29, 2010
  5. smoge macrumors regular


    Jun 14, 2011
    you could drop resolution so that you could shout more fps but you would get no were near 300 fps even if you halt the resolution and size of the frame.

    good idea though :)
  6. psonice macrumors 6502a

    Jul 22, 2005
    You won't get more than 30fps out of the camera, so far as I'm aware (and I've been doing lots of low level camera development for months) it's capped.
  7. TwoBytes thread starter macrumors 68030


    Jun 2, 2008
    I think that nails it as an answer, thank you!

    Some compact campers have this effect built it but with lower res images to record at higher fps. I was hoping for an iphone app to do that and blur the effect so it looks fancy.

    here's hoping for ios5....
  8. kRobbin macrumors member


    Jan 6, 2011
    Boulder, CO
    Hope iPhone 5 will increase frames per second which would be the only viable way to do slomo.
  9. cgehrke macrumors newbie

    Mar 23, 2012
    the app called "Slowmo" will slow down your video or speed it up using the iphone 4, 4s and 3G (it think).

    It's not perfect but it's not bad on the iphone 4s to be honest.

    Not tried on any other iphone yet.
  10. Qaanol macrumors 6502a

    Jun 21, 2010
    You can record at 60fps (at up to 720p resolution) if you modify a plist (I don’t know if it requires a jailbreak—I know I modified some plists before jailbreaking and the effects worked, but this particular mod I only did after jailbreaking so I can’t promise it’ll work without.)

    To enable 60fps video recording at up to 720p resolution, locate the file /System/Library/PrivateFrameworks/MediaToolBox/N94/AVCaptureSession.plist and make a backup. Then modify a copy of it as follows. First, identify which video profile your favorite app uses that you want to change, within Item 0 of AVCaptureDevices. For me, I use the ProCamera app which has 4 video quality setting to choose from, and I wanted to change one of them to this.

    First I changed all the video profiles in the plist to capture at different sizes (I went with 300, 310, 320, etc. pixels). Then I recorded a video in each mode, and on my computer checked which video was at which resolution. Having thus identified the plist key I wanted to change, I put all of them back at their default values except the one I wanted to change I renamed with “original” at the end, and renamed a copy of AVCaptureSessionPreset1280x720p60 in its stead. The TemporalNoiseReduction key had value 11, but I had to drop it down to 1 in order to get it to work fast enough for 60 fps. It works at 0 too, but then the video looks wicked noisy.

    Once you’ve recorded 60fps video, you need to change the playback rate to 30fps (or whatever you want). I think that iMovie can do that, but I don’t have iMovie so here’s what I did.

    On a Mac you can use Apple’s free Atom Inspector (available through or to change the movie’s “timescale” from 600 to 300 (or whatever you want playback speed to be) in both the Movie Header and the Media Header for the video track.

    That only affects the video track though. For audio I used Ambrosia Software’s WireTap Studio (costs money) to double the length of the sound track without modifying the pitch, then I used Subler (free) on passthrough mode to put the lengthened audio and video tracks back together into one movie.
  11. TwoBytes thread starter macrumors 68030


    Jun 2, 2008

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