Change fps of a video while keeping the audio consistent with that frame rate.

Tom1323241Tom1323241 Website User Posts: 2

 I currently have a 60 fps video but I'm editing in 30fps. I want to have a clip of 50% speed so what I did was, I clicked the little cog Icon beside my clip in the media tab and changed the fps to 30. When I view it in the trimmer, the audio's speed was not reduced and I can only view half the clip before it just stops. Is there any way I can fix this? PS I don't mind if there's a fix that just removes the audio but I much prefer to keep it and maybe slowed down.


  • PalaconoPalacono Website User, HitFilm Beta Tester Posts: 3,442 Enthusiast

    Not in Hitfilm; you'd have to export it separately and use something like Audacity, which is free, then reimport it.

  • CleverTaglineCleverTagline Moderator Las Vegas, NVModerator, Website User, Ambassador, HitFilm Beta Tester Posts: 3,029 Ambassador

    @Tom1323241 @Palacono Actually this can be done in HitFilm, though using the trimmer will be tricky as you noticed because the normal audio and the slower video aren't in sync.  However, if you don't mind trimming in the main editor timeline, this will work.

    After changing the clip properties from 60fps to 30fps, drop it onto the timeline.  You'll notice that there are hash marks at the end of the audio where it no longer plays.  Just disregard that for now.  With the clip selected, right-click on it and choose "Unlink."  Deselect the clip, then select only the audio portion.  Grab the end of the clip and trim it back to before the hash marks. Let go, then click and trim it back to the right.  Notice that it stops at the end of the actual audio.  Now change to the Rate Stretch tool.  Grab the end of the audio and stretch it back out to match the length of the video, which should be easy because HitFilm will try to snap the two ends together.  This will give you slower audio to match the slower video.  Now go back to the main selection tool, marquee-select both the audio and video, right-click, and choose "Link."  They're now tied back together as a single clip.  This re-syncing of audio and video can't be brought back into the Trimmer tool, so you'll have to trim directly on the timeline, but it gets everything back in line.

    If you want to process the audio back to normal pitch after doing this, drop the Pitch audio effect onto the clip.  For a 50% rate drop (60fps to 30fps), set the Semitone Shift to 12, which will raise the pitch back to normal. Granted it's not the most clean of pitch shifts (other audio software may be able to do it better), but it may work for your needs.

  • PalaconoPalacono Website User, HitFilm Beta Tester Posts: 3,442 Enthusiast
    edited January 2018

    @jsbarrett Ah, nicely explained :) But, that's why I (and Triem23 and others) don't use Hitfilm to Edit. In Vegas - Pro or Movie Studio - you stretch the clip and the audio stretches with it and retains the correct pitch.  Once you've tried it, no going back.

    Be nice if FXHome could licence the  élastique code; even if only for Pro because: cost.

  • Juda1Juda1 Website User Posts: 300

    Regarding your example of half speed: Why don't you drag the clip on your timeline and set speed/duration to 50%? That also sets the Audio to 50% and that is what you wanted - or am I missing something?

  • PalaconoPalacono Website User, HitFilm Beta Tester Posts: 3,442 Enthusiast
    edited January 2018

    @Juda1 yes, the problem is the audio is lower pitched and when you add the Pitch Effect and increase the pitch to get it sounding normal: it gets quite crackly sounding. You can't push it too far. Also, once you add the 60fps video to the 30fps timeline, those extra frames are just gone. So when you slow it down to 50%, it just doubles up frames, rather than using the 'in between' ones that were originally there. 

    Worse, using the Speed Effect instead: every alternate frame will be a blend of the two either side. Both methods need a toggle for that; sometimes you want it, sometimes not.

    You could try a combination of things where you use the audio from that Speed/Duration method with the video from the 'Change properties in the Media Bin' method. Or maybe that's what JS was suggesting. I didn't follow it all, knowing I'd never need to do it, but assumed he'd got it right because he usually does. :)

  • Tom1323241Tom1323241 Website User Posts: 2

    Thank you guys very much for the help :)

  • CleverTaglineCleverTagline Moderator Las Vegas, NVModerator, Website User, Ambassador, HitFilm Beta Tester Posts: 3,029 Ambassador

    @Palacono My notes were simply to point out that it's technically possible to re-sync the audio with a clip that's had its base frame rate changed in the media bin.

    The pitch shift effect in HitFilm is, frankly, not that good, but the HitFilm team aren't claiming to be audio wizards.  :) If maintaining the pitch is important when slowing things down, then I strongly recommend using dedicated audio software to do the job.  I use Reaper, which comes with some very nice tools for pitch and time shifting, though they're still not top-of-the-line.  Unfortunately I haven't delved very deeply into that pool of audio knowledge, so asking me for recommendations will (sadly) not do any good.  Sorry.

  • NormanPCNNormanPCN Website User Posts: 3,945 Enthusiast

    The Elastique time stretch code that Vegas licenses is pretty good., as Palacono mentioned. Even movie studio has it I think so the license cost can't be too much.

  • xiqiaozhangxiqiaozhang Website User Posts: 1

    CleverTagline Thats exactly what I want to know about. Thank you so much.

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