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[SOLVED] Help/advice for creating real time 120fps video.

Posted: 01 Jan 2017, 13:05
by Xx123456xX
I just got my first 120hz computer, an Asus G701vi laptop. I downloaded the Vegas Pro 14 trial and importing Hypermatrix's BF4 clip it seems to be able to render real time 120fps. However, no matter how many tutorials I read I can't figure out how to install ffmpeg to speed up slow motion camera footage to 120fps.

Does anyone know of a different way to speed up slow motion without dropping frames? I would greatly appreciate it.

Sorry if I posted this in the wrong forum.

[SOLVED] Help/advice for creating real time 120fps video.

Posted: 02 Jan 2017, 19:09
by Chief Blur Buster
The command line to speed up 120fps slow-mo videos to 120fps realtime is at:


Code: Select all

ffmpeg -i slowmo120.mp4 -r 120 -vf "setpts=(1/4)*PTS" -an realtime120.mp4
The 1/4 is because the slomo 120fps is played at 30fps which is quarter-speed.
So this speeds up the video by 4x, to modify a 120fps slo-mo video play in real-time 120fps on a 120Hz monitor.

Works with almost everything, including iPhone, Android, and GoPro
(The GoPro Hero 5 BLACK 1080p@120fps -- produces amazing 120fps@120Hz videos -- after conversion using ffmpeg!)

This even works with 240fps videos for the new 240Hz monitors (i.e. Benq XL2540, Acer XB251HQT or Asus PG258Q) though you will need to substitute "-r 120" with "-r 240" and[/b] substitute "1/4" with "1/8" (to do an 8x speedup) -- and playback using a very powerful GPU capable of the unusually high video framerates. I found that VLC plays smoother on specific Radeon's, while Windows Media Player plays smoother on specific GeForces, but some may find some players plays imperfectly/perfectly -- playback precision is still a problem at 120fps and 240fps -- but it works on several cards.

Currently, on Windows 10 using latest NVIDIA drivers, the latest versions of Chrome, FireFox and Edge, all seem to play VGA-resolution 120fps@120Hz embedded videos properly. 1080p 120fps videos work well (test 120fps video, albiet gameplay rather than a GoPro 5) if your GPU is powerful enough but it tends to stutter while downloading. Once it finishes downloading, it tends to play properly smoothly. (Audio leaves quite a lot to be desired, but that can be recorded separately, using a 2nd device, and then subbed-in post-op)

Re: [SOLVED] Help/advice for creating real time 120fps video

Posted: 02 Jan 2017, 20:07
by Xx123456xX
Thanks for the info, but I've discovered some slow-motion cameras actually create a 120fps file that must be manually slowed in post production. This should mean if imported into Vegas, it should play real time 120fps. But anyone wanting to go above 120 will still have to use another tool, as I tried to enter 240 for the project frame rate but it reverted to 120.

Re: [SOLVED] Help/advice for creating real time 120fps video

Posted: 02 Jan 2017, 23:02
by Chief Blur Buster
Yes, some cameras run the slow motion footage at realtime framerate... Though the other cameras play 120fps files at 30fps, which needed the above specific ffmpeg command to speed the footage up.

I presume some software has a limitation against doing videos above the display refresh rate or has a hardcoded rate ("120" or, much more annoyingly, "60"). In theory with this software you could work on these files at 120fps (half speed) and then convert the videos to double speed as a final lossless post-production step using an ffmpeg command. Though that probably will wreck the audio...