Hi All,

This is my first post. In fact, it's my first day with my Spark, which I'm very excited about. However, I have a question, which I'm hoping to get the answers to.

I film a lot of stuff currently with my iPhone X in 4K at 60fps. I'm about to change that down to 1080 at 60fps as I don't need the extra resolution.

One of the things I do with my footage is slow it down when it's shot with my gimbal to get that buttery smooth effect. I don't use anything too technical.. at the moment, it's iMovie but I'm soon going to switch to Luma Fusion on my iPad Pro which looks insane!

I really want to start shooting on my Spark and get that lovely slow mo effect (almost like you see on the Apple TV screensavers) where it's not just the drone moving slowly, but also the cars etc beneath are just mildly slower too. I think this would be classed as filming in Tripod mode.

I've noticed that videos on the Spark that have been slowed down (all the ones I see on YouTube anyway), seem to be mildly juddery. I assume that's because it's slowing down 30fps and there isn't much to play with (I'm very new at this, so forgive the naivety!).

I'm wondering what ways there are to get around this? I've been looking at buying some of the Polar ND filters.. Would that work? I don't really know what I'm doing here, but know what it is I want to achieve. I don't want to have it completely slow mo to the point that stuff is barely moving, but just slowed down a little bit - maybe 50%.

Can anybody please offer any advice? (In idiots tems - remember, I'm fairly new!)

Thanks in advance.

just listening in here :-)

DK Sparky Posted at 2017-12-12 09:31
just listening in here :-)

Fingers crossed we'll be drowned out by the noise ;-)

" I assume that's because it's slowing down 30fps and there isn't much to play with (I'm very new at this, so forgive the naivety!)."
Yes, "not much room to play" is the technical term. Nah, just kidding. At 30 fps you simply don't have enough frames to create a smooth SloMo. The flicker rate of the human eye is said to be around 18 fps where you can tell frames apart - that's why movies were shot at 24 fps in the film era...


SloMo: The more fps the better. That's why a lot of footage is shot with 120 fps to create a smooth footage up to 1/5 playback speed (I'm spoiled by FliteTest and Francis Darracott). That's why a lot of the action cams (GoPro) and higher rank drones (Phantom 4 Pro, Inspire, ...) do have the 1080p 120 fps mode. Everything's looking better in slow motion...

A few days ago I found a demo of how “optical flow” can interpolate in-between frames to make it look better.
(Where was that?). I hope I have said enough.
I think premiere, da vinci resolve, fcp and others has it.
Well,

heliman Posted at 2017-12-12 09:58
A few days ago I found a demo of how “optical flow” can interpolate in-between frames to make it look better.
(Where was that?). I hope I have said enough.
I think premiere, da vinci resolve, fcp and others has it.

Hmmm.. I saw somebody talking about Optical Flow on a Premier video. I didn't quite understand it.

I'm a bit hesitant to get Premier or FCP though. Not because I'm tight.. but because it's a lot to spend on just one task.. Also, I'm broke after buying the drone! Ha ha

Spark video codec uses VFR variable frame rate. Run the file through Handbrake to produce a CFR constant frame rate.

fans40e50745 Posted at 2017-12-12 11:03
Spark video codec uses VFR variable frame rate. Run the file through Handbrake to produce a CFR constant frame rate.

Great - thank you for this.

I haven't used Handbrake for years. Not since the days when we'd rip DVDs! I didn't even know it was still around.

So what would be the best course of option?
Video is shot at 30fps, so do I change it to CFR of 60fps, then import it into my editing software to slow it down so that it's smooth? Is it that simple? Would I need to change the bitrate too?

Apologies if this is all obvious - but it may as well be in Swahili to me!!

LAphil Posted at 2017-12-12 10:43
Hmmm.. I saw somebody talking about Optical Flow on a Premier video. I didn't quite understand it.

I'm a bit hesitant to get Premier or FCP though. Not because I'm tight.. but because it's a lot to spend on just one task.. Also, I'm broke after buying the drone! Ha ha

The free version of da vinci resolve can do optical flow.
I just tried it.
Constant bitrate flag set (is that good?).
Retimed to 50%
Optical flow

Seems to work.

Motion interpolation or motion-compensated frame interpolation (MCFI) is a form of video processing in which intermediate animation frames are generated between existing ones by means of interpolation, in an attempt to make animation more fluid and to compensate for display motion blur. Some video editing software and plugins offer motion interpolation effects to enhance digitally-slowed video. Adobe After Effects has this in a feature called "Pixel Motion". The effects plugin "Twixtor" is available for most major video editing suites, and offers similar functionality.

These programs require a computer that is very robust. It is really system intense. Most video interpolation takes a long time to process and only works for clips that are realitivity short in length (think 10-15 seconds) The program is creating additional frames to place in between the existing frames to approximate what the movement should be. After Effects is the leader in this area and the program is expensive.

Sidd

heliman Posted at 2017-12-12 14:35
The free version of da vinci resolve can do optical flow.
I just tried it.
Constant bitrate flag set (is that good?).

Your footage looks great.

Although, am I being a total idiot? I try to install the free software and it won't let me progress past the initial setup without some kind of specialist equipment connected to my computer

Sidd Finch Posted at 2017-12-12 15:40
Motion interpolation or motion-compensated frame interpolation (MCFI) is a form of video processing in which intermediate animation frames are generated between existing ones by means of interpolation, in an attempt to make animation more fluid and to compensate for display motion blur. Some video editing software and plugins offer motion interpolation effects to enhance digitally-slowed video. Adobe After Effects has this in a feature called "ixel Motion". The effects plugin "Twixtor" is available for most major video editing suites, and offers similar functionality.

These programs require a computer that is very robust. It is really system intense. Most video interpolation takes a long time to process and only works for clips that are realitivity short in length (think 10-15 seconds) The program is creating additional frames to place in between the existing frames to approximate what the movement should be. After Effects is the leader in this area and the program is expensive.

This sounds waaaaaaay above my limitations, Sidd

LAphil Posted at 2017-12-12 13:12
Great - thank you for this.

I haven't used Handbrake for years. Not since the days when we'd rip DVDs! I didn't even know it was still around.

Spark records 1080p/30 at 24Mbps so I set the frame rate a constant30fps and a constant bitrate of 24000 kbps.

LAphil Posted at 2017-12-12 18:30
Your footage looks great.

Although, am I being a total idiot? I try to install the free software and it won't let me progress past the initial setup without some kind of specialist equipment connected to my computer

I don’t know. I use a mac mini 2012 and had no such issues.

Adlibber Posted at 2017-12-13 00:35
Spark records 1080p/30 at 24Mbps so I set the frame rate a constant30fps and a constant bitrate of 24000 kbps.

Another very useful free tool is "Mediainfo". This tool will inform you of the myriad info hidden away in the MP4 container. The juddering problem results from most (all?)  video editors using the far more efficient non-linear system of editing. The web has a lot on this. iMovie and Adobe Premiere Pro are NLEs. Because of the way they work NLEs cannot properly handle VFR video files, they have to be CFR files. Just how VFR is implemented I'd love to know! But it's very important in compressing static imagery.

LAphil Posted at 2017-12-12 18:31
This sounds waaaaaaay above my limitations, Sidd

The best way to see if it is something you feel you can attempt is to try searching youtube for some how to videos. It might be something that you can do after all.

Sidd