Weird Artifacts in Slow Mo when Rendered.

I often shoot at 30fps (29.7 technically) and then slow it down to 24fps (23.976 technically), and if I render it for youtube, I get weird artifacts.

https://www.dropbox.com/sh/32qut52v64wd ... DY0xa?dl=0

This is most noticable on the wood fence on the camera left in the beginning of the first two clips.

This happens when I render using the youtube 1080p 23.976 rendering. I don't notice when I am watching it on the timeline, or if I render the project to the h.264 Master format.

However, if I render to H.264 (instead of youtube 1080p preset) the file size is HUGE!!! (672MB vs 109MB for this very brief video).

So is there any way to render this without all the crazy artifacts without ending up with a huge file? Most of my videos are about three minutes long so they would probably end up being several gigs in the h.264 master format.

To achieve the Slow Motion, I am:

1) Shooting at 4K 29.7fps

2) Create a project with a 23.976 timeline

3) In the Master Settings -> Frame Interpolatin, I have it set to Retime Process = Optical Flow, Motion Estimation Mode = Enhanced better, Motion Range = Medium

4) Import the media and clicking NO when it asks if I want to change the timeline framerate to match the clips framerate

5) In the media pool, right clicking the clips recordered at 29.7fps and changing the clip speed to 23.976

Again, they look fine when scrubbing through / playing the timeline in the edit page, but when rendered to the youtube 1080p preset they look horrible.

Thanks in advance.

What kind of artifacting are you referring to? Sounds like you're talking about H.264 macroblocking, in which case I suggest just manually set the bitrate.

What kind of artifacting are you referring to? Sounds like you're talking about H.264 macroblocking, in which case I suggest just manually set the bitrate.

Thanks for the reply, Mark.

If you download the rather short video, you can see what I am talking about. It is about 110 megabytes. Not huge.

Is there a good bit rate to set to avoid the macroblocking (without making the file too large)??? I am trying to keep the average three-minute-long video under 400 MB. I am exporting as 1080p 23.976fps

Thanks in advance.

A 3 minute video at 17Mb/s should be about 400 MB.

A 3 minute video at 17Mb/s should be about 400 MB.

Thanks for the reply.

Just to make sure I understand, I should pick the youtube 1080p default but change the bit rate from 10000 to 17000 is that right???

Thanks in advance.

A 3 minute video at 17Mb/s should be about 400 MB.

Thanks for the reply.

Just to make sure I understand, I should pick the youtube 1080p default but change the bit rate from 10000 to 17000 is that right???

Thanks in advance.

You don't have to pick the YouTube 1080p option. Just make sure the codec is h.264 and set the bitrate to 17000.

A 3 minute video at 17Mb/s should be about 400 MB.

Thanks for the reply.

Just to make sure I understand, I should pick the youtube 1080p default but change the bit rate from 10000 to 17000 is that right???

Thanks in advance.

You don't have to pick the YouTube 1080p option. Just make sure the codec is h.264 and set the bitrate to 17000.

I just wanted to say thanks for this. Yes, I have been setting the bitrate to 20000 and it seems to work fine now, so thanks again.