Saturday, November 05, 2022

Processing slow motion GoPro video in DaVinci Resolve 18

Got out to the shooting range today with the GoPro Hero 9 Black and captured some 240FPS 1080P video.  Now, all the SlowMo folks on Youtube note that the audio is 'fake' - well, you can actually use a couple of tools to get the audio and video sorted out with slow motion playback of your high framerate video! 

First, in DaVinci Resolve, set your project and timeline to 24FPS:

Next import your clips from your GoPro, and then change the clip attributes to 24 FPS! Yes, this is going to make some very long clips - but they are playing at 1000% slower than realtime.  Set your in and out points, or just drop the clip on the timeline.  Unlink your audio and video by right clicking on the clip, and unchecking the 'Link Clips' bit.
Now you have video, but no audio.  What good is that?  Fine if you just want to lay in a music background track, but if you were doing like I was - shooting with distinct reports you want matching the muzzle flash - you need to stretch out your audio.

In comes Audacity to solve the problem.  Open your MP4 file from the GoPro in Audacity.  Yes, it's an audio editor.  Yes, it opens video files just fine.  You'll see the audio track waveform across the screen.  Now, just a simple retime and export and you have audio to match your video!

Since you are going from 240FPS audio to 24 FPS audio, you'll need to slow it down by 90% - or 0.10 of original playback speed as such:

Export the audio (File - Export) as a WAV, saving it in your source video working directory.  Drop it in the media pool and then drag it to the timeline.  Now you have video and audio at 24FPS!  It will take a bit of sliding the audio file around to match it exactly to the video file; hopefully you have a marker (a clap, a gunshot, something loud and visual) to sync the audio waveform up to the video file. Once synced, you can re-link the new audio clip to the video clip and go about your editing!

Mind you, it's not 100% perfect - you may find the audio drifts out of sync with the video over time, so you will have to make a cut, unlink and readjust the audio, and relink it once re-synced.  I'm sure there are more reliable and repeatable processes out there, but I wanted to share what worked for me tonight. 

With no further ado - a couple of brief videos made from high framerate 240 FPS GoPro footage slowed to 24FPS capturing muzzle flash from a handgun.


Enjoy the process!  (I've spent almost 5 times longer editing this than actually shooting the video!)

- Will

Sunday, October 30, 2022

iPad Safari post

 Just seeing how well the web works with Safari on iPad for writing blogs, adding photos etc. 

A Photo: 

Ok, seems to add photos OK.

Good enough for my purposes.  Now to figure out how to add a website to the iPad Home Screen 

- WIll

Sunday, September 11, 2022

You think you know what you’ll do…

 You think you know what your’ll do when something happens - but then then reality hits. You get down because life has changed to the point that you don’t see a point. Years ago, you had figured when life wasn’t making sense, you’d take that time and go ride the motorcycles until you had a new head of memories and life to look at; a new foundation to work from as you build the next few years of life. 

But, when time comes to pass, and life fails to have a point, you find that the dullness is within you. You have become dull, lumpy, weak.  Just jumping up and going on a tear around the country is beyond you. Turns out, the journey you must undertake is to rebuild yourself before you can do anything to get beyond the pointlessness. So, beyond pointless, you find you are below water in simple ability to do anything about the pointlessness. And you have 6 months, or a year, or 3 years worth of work ahead of you rebuilding your body and rebuilding your mind to reach a place where you can adventure again. 

Oh, but any journey starts with a single step, right?  Why sure it does, but that same step can also take me to a gaming computer where I can escape from the pointlessness for hours on end, or to a TV bigger than some movie house screens and lose a half a day in edutainment or fantasy movies. 

Beyond taking a first step, you have to take the right first step. Every day.  Several times a day.  Step away from the computer and go work out, even if it’s just carrying sticks and cutting the lawn. Or painting the house.  Or cleaning the garage so you can find the parts and gear to adventure with. 

Taking the right step is hard.

Taking the right step is scary. 

But a decision must be made. 

That is my story now.

Wednesday, January 05, 2022

Fun with Exponential Trends (COVID-19 numbers from Johnson County, KS)

 Just playing with the COVID-19 numbers from Johnson County, KS today.  We've hit quite a spike the last week. From :


So I sampled the last 60, 30 and 7 days data, added an exponential trend line for 30 days and came up with this:

Here - let me expand the end of those trend lines if you can't see them.

60 Days:

30 days:

And 7 days:

Statistics are fun. 

Realistically, we'll end up somewhere in the 60 or 30 day pattern; I don't think the population would support 60,000 active cases of COVID-19 in Johnson County Kansas each week; we'd end up with more cases than people in a very short order.

Aprapo of nothing really.  Off to my next meeting.