Rendered 4K has artifacts

DumplingandDots wrote on 6/3/2016, 10:18 PM
When I render in Vegas to an custom MP4 the video comes out with artifacts. It is especially noticeable with movement. When I imported the files into Vegas, it automatically set my project to 3840x2160x32 23.976p (Which is odd because in my camera settings it is 24p 100m super 35mm) and I rendered to the closest frame rate of 23.976i. The original footage are two different codecs. ProRes HQ 10 bit from Video Assist 4K and Xavc S 4K 8 bit directly from the Sony a6300. For the life of me I can't figure this out and it's becoming frustrating to know that my original footage is clean , sharp and free of artifacts. Please advise!


NickHope wrote on 6/3/2016, 11:07 PM
Background reading. Some devices record true 24.000fps... "24p" (e.g. My Panasonic GH4) and some devices record 23.976fps "24p" (e.g. My DJI OSMO). It's 23.976fps but they still call it "24p". This difference between modern devices is a PITA.

Confirm what frame rate your footage from each device is by
1. Right clicking on a clip in the Vegas Explorer window and choosing "Properties", or
2. Match your project properties to a clip (top right of the Project Properties window... or drag a clip to a new project, as you have done) and see what it gives you, or
3. Mediainfo, which is an invaluable tool and will give you more information.

If the frame rates are different for your 2 devices then decide on one output frame rate or the other and match the "non-conforming" clips to it by accurately stretching them like this:
1. Drop the non-conforming clip on the timeline at 0
2. Match the project properties frame rate to the clip
3. Right click on the ruler above the timeline and set it to "Absolute frames"
4. Zoom in and note how many frames long the clip is
5. Repeat until you have a list of lengths of all the clips
6. Switch frame rate to your desired output frame rate
7. Hold <CTRL> and drag the end of each clip until it is the same number of frames long as it was before
8. You can render intermediate files if you don't want to work with the footage in a "stretched" state

If you have a lot of clips to conform then you can use this script. You'll need to edit the target frame rate in the script. Then just select the clips on the timeline and run the script. Note to SCS devs: Please give us a "conform frame rate" command to automatically do that!

The difference between 24.000 and 23.976 isn't much but it can build up over a long timeline.

23.976i is an interlaced format. Assuming you're working with progressive footage in and out then you want to avoid interlaced completely. In your render template set "Field order" to "None (progressive scan)". Note that if the exact frame rate you want is not in the drop down lists you can manually type it into the "Frame rate" field in a Render > Custom Settings window or the Project Properties window. Note to SCS devs: So many people miss this. Please make "Frame rate" work the same as "Frame size". i.e. A (custom frame rate) entry at the top of the drop-down list and a box below that you can obviously type in.

What is your delivery medium/format?
DumplingandDots wrote on 6/3/2016, 11:25 PM
Thank you for your detailed help!!! In regards to the render options i did what you suggested for frame rate and size. Also I did the progressive scan and my footage has this blocky, pixelated look moving through the image. The delivery format is for YouTube, but I still would like to have high quality 4K renders for future proofing. Once again thank you and I will read your suggestions and follow it and update you.
NickHope wrote on 6/3/2016, 11:32 PM
If the output footage is blocky or pixellated then you'll probably need to choose a higher bit rate in your render template (or higher "quality" in some codecs). Again, you can often manually type in a higher bit rate if what you want is not shown in the drop-down list.
DumplingandDots wrote on 6/4/2016, 12:08 PM
I followed your advice and made sure that my variable bitrate was high and also turned off gpu rendering to achieve better results. I think it's actually the MainConept's MP4 codec that is causing the artifacts because as a "clean" xvac s render, the footage is nice. Also I tried Handbrake to render the footage into an MP4 and I still experienced the blocky artifacts through the image.
musicvid10 wrote on 6/4/2016, 12:50 PM
That says to me that you may have undetected stream errors in your source.
It wouldn't affect playback devices, but will show up in an encoded version. The fact that the blockiness didn't go away in handbrake is a clue.

Run your video through the "quickstream fix" utility in VideoRedo TV Suite trial version, and if lots of drops occur in the final message, stream errors would be the source of your problem.

DumplingandDots wrote on 6/4/2016, 1:44 PM
Goodness I never even heard of "stream errors" smh. How does one accrue stream errors and would the software recommendation correct it? How can I avoid such stream errors in the future?