Using 120FPS GoPro Footage in a 25FPS Project

Hi there, Hit Film Express Noob here.

I'm trying to use a 120FPS clip from a Go Pro in a 25FPS project, the GoPro clip is placed in a composite, which I can only set the framerate up to 100FPS for the highest. This obviously desyncs my video and audio in the output.

I try to set the Composite's properties to 25FPS, but then I'm left with a blank clip on the timeline.

Any help on how to properly use my GoPro clip in my project? Thanks!

Comments

  • Hey there, please give us a Mediainfo report, of the file you're using. We have really good experts in our community. I don't even know half the things they're saying. 

    Also, post your full PC specs, as it might help, so you don't have to do it later.

  • First, do you want the 120fps file to play at normal speed?

    Then just place the media in your project, whatever your project framerate is. Hitfilm will automatically conform the source framerate to the project framerate. From your post is seems like you want a 25fps target project/composite rate.

    Typically the only reason to record at such a high framerate is to get quality slow motion. Nobody delivers 120fps playback. Even 60 is often debatable. For slow motion from your 120fps file, right click the media after imported and set the media file framerate to the slow motion factor you want. GoPro 120fps files are actually 119.88 (29.97 * 4). So if you want 4x slowmo set the media framerate to 29.97. 2x = 59.94. You get the idea. For what it's worth at a 25fps target speed you will get a slowmo factor of 119.88/25 = 4.8.

    Note that you can import a media file more than once in case you want to get multiple different playback speeds for a given source media file. Normal and slomo for example.

    I do have a GoPro Black 3+ so if you have problems I can probably help.

  • Hi Norman,

    Basically I'm doing a video comprising of both 25 and 120 clips, the video is mainly 25FPS, with the Hi Rate clips being used to deliver smooth slow motion as you mentioned.

    I'm quite familiar with framerates and how slow motion works. I've been using Cyberlink PowerDirector previously which were interpolating to my final output FPS properly.

    So I started a new 25FPS project and then I dumped the 120FPS clip in the following manner.

    • Dump from media window into project timeline directly
    • Create a composite shot but leave the FPS at 119 untouched
    • Create a composite shot but touch the FPS in the composite's properties window causing HitFilm Express to max it out to 100 FPS

    And all of them are exhibiting signs of audio/video desync.

    BTW, setting the duration in the media pane causes the video to run at the desired framerate, giving a proper slow down effect, but the audio still runs at the original rate.

  • edited May 2016

    If you really want the audio slowed down you can place the audio only only an audio track and use the rate stretch tool on the audio only to slow it down.

    For my curiousity what is your audio in this clip? Maybe its my limited vision, but I cannot understand what one could want with slowed down audio. It will be distorted and incomprehensible.

  • Ok, stretching the audio would be fine, but it doesn't fix the problem of when I need the video playing at normal rate instead of slow motion. Like I mentioned, there's an audio/video desync when I just drop it in the project timeline.

  • Triem23Triem23 Moderator

    Double check your media for fractional timelines. Hitfilm is very literal on framerate and there's a difference between 119.97 (what I think a GoPro shoots at) and 120, and that difference is a sync drift of one frame every 10 seconds or so. 

  • CNKCNK
    edited May 2016

    @Triem23

    When I record with my Canon, I choose 1080/24p in the menu, but according to Mediainfo, it's 23.976. I can't even force 24p with Magic Lantern (no sound), which makes me believe it doesn't exist? Might be the same for OP, no? Maybe converting to constant framerate?

  • Triem23Triem23 Moderator

    In the case of 23.96 it's not variable frame 5,it's a quirk of NTSC broadcasting. In the old days of SD video, when color was added to the existing black and white signal SMPTE engineers weren't able to hold a true frame rate of 30fps. The 29.97 frame rate drops one frame every 10 seconds (time code goes from 09:29 to 10:01 and skips 10:00).

    Film is a true 24 frame rate, but the "24p" mode for DVD they crammed that in the 29.97 frame rate. Hence the 23.96. 

    23.96 is a constant framerate, but is different from 24.

  • Well I'm not concerned about the exact fractional frame rate being reported in Hit Film, I just want to know how to make a 120FPS clip work properly in a 25FPS project without desynching.

  • edited May 2016

    For some reason Hitfilm seems to chop the GoPro 120fps (119.88) files to 119. If that is a display issue only or a functional one who is to say at this instant. That may be a reason for any desync you notice. It's okay if they want to arbitrarily limit a project/comp to 100 fps as they do, although why do that. However, they should never mess up the literal source file rate.

    Unlike most cameras recording in "slowmo" mode, GoPro marks the output file at the full framerate. So when it captures 120/240/480 fps the file fps will be that respective rate. They probably do this since action cam users might just set the high rate for everything and just in case anything cool happens they can have slowmo. I've done that but I was recording 1080p60, only intending 30p edits.

    I'm going to setup a GoPro 720p120 test and look for potential Hitfilm quirks given what Marauderz is reporting.

  • Yes NormanPCN, that's my  use case. Film in high framerate so thatI can slow stuff down when needed. Doesn't mean I want all my footage in slow motion.

  • edited May 2016

    I confirm the audio desync with Gopro 120 fps files when placed onto a timeline and played at normal speed. I tried a 29.97 timeline. I submitted a bug report and example file in case @Marauderz has not already done so.

    Also, Marauderz you may want to transcode the source to your project rate for the normal video playback edits. Even if the playback bug were fixed tomorrow you might get better edit performance using a transcode.

    The Hitfilm conformance code may not be efficient enough for good performance. Depends on your machine. 120fps to 25fps is throwing a lot of frames away. It all depends on how the conformance is performed and the source structure.

  • Thanks for the assist Norman, hmmm.. back to using PowerDirector to transcode first then. :P

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