x264 jaggies on lower resolutions

I'm hoping to find a good solution for this:   We are getting stairs / jaggies on lower resolutions.  As background, we've largely been using Wirecast 6, and have transitioned to Wirecast 11.  Colors are much improved, but it seems the scaling algorithm has changed for the worse. 

We are using Wirecast Pro 11.1 on Windows 10 Enterprise.  I see the same issue across three systems:

Intel Core i7-8700K w/ 32 GB RAM
Win 10 Enterprise v1803
NVIDIA GeForce GTX 1080

Intel Xeon Silver 4110 w/ 16 GB RAM
Win 10 Enterprise v1803 
NVIDIA Quadro P1000

Intel Xeon CPU E31220 w/ 12 GB RAM
Win 10 Enterprise v1809
NVIDIA GeForce GT 620  (NVidia encode not available)

Canvas size is 720p, which matches our production pipeline.  It doesn't matter if the source is live, or imported image or video.

The issue is most noticeable on the 360p encode, so all my captures are from that. I used the default 360p30 selection for x264 (0.75Mbps).   I also used the default 360p30 NVIDIA (1Mbps) selection to compare.  I archived to MP4 and took screen shots.  The result matches what I saw via live stream. 

It's like the scaling sharpness is set too high?  Jaggies can be seen on the diagonals, and the small lettering on the b&w image becomes unreadable in the x264 version.

Simply going to NVIDIA for everything isn't an option because 1) It will only accept two encodes at a time and 2) some of my hardware doesn't offer that option.

CPU time is fine..  for the highest powered machine, I can run several bitrates with x264 not break 25%.  

What can we do?

(edit: Sorry for not labeling the images.. looks like the NVIDIA version is first, followed by the x264 version)

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  • Just to be clear, NVENC looks better than x264.

    Going from 720 to 360 involves scaling and the smaller the text the greater potential impact.

    Since you mention this was better in earlier versions can you provide comparison to an earlier version?

    We make available versions all the way back to 6.0.8 if you need. If you don't have the installers you can find the downloads at this link under Previous versions at the top.

    Testing with the most recent earlier version which shows better quality. (is 10.1 better?). 

    Providing a direct comparison with an earlier version of Wirecast would be most helpful. Thank you for doing that.

  • CraigS Yes, NVIDIA scales better.  And the text was just there in the test to help evaluate how well the scaling is working.  You can see it is far more readable in the NVIDIA version.  The reason I'm investigating this is that our first major webcast using Wirecast 11 revealed lots of walking stairs on the edges and a sense the video was "pixelated".. which should not be what you see in a scaled down video!

    I will get captures of our current Wirecast 6 set, and then evaluate the other versions.  We have licenses for 6 and the current year of 9-11.

    Has anyone else seen an issue with scaling with x264?

  • David Wilkins I don't recall other reports with 11 specifically. I thought we had improved an earlier report and I think that was NVENC scaling. Perhaps we improved that and not x264. Do test and post the example with an earlier version of Wirecast.

  • Okay, here's what I've found.  Looks like I'm getting the scaling issue starting with Wirecast 8.3 compared to Wirecast 7.7.  (versions 6 and 7 look similar).   Based on the release notes, that coincides with the new render / encoding engines in Wirecast 8.  

    We can see the old black line issue on the the top and left on W7 which is fixed in W8. Colors are better on W8. But that scaling!

    I did actually run through all the versions from 6 through 11.  The 7-8 upgrade is where the change is, and no other noticeable changes after that.

    What should I do next?

  • David Wilkins Thank you for doing all this.
    Your visual examples are most helpful to us.
    Fill out the form and include these details (you can link to this forum thread). We'll send you a case number while we investigate the fix. Knowing which version the change occurred it is important for us in investigating this.

    Wirecast Support Form

  • CraigS Support request submitted.  Thanks!

  • David Wilkins You're welcome of course. We know can track the changes in developement and investigate how to handle. If you're willing can you post your case number (or send it to me via forum private message) to help me track this internally.

  • CraigS Case #00623389  x264 jaggies on lower resolutions

  • David Wilkins Thanks. I'm following it. 

  • CraigS I sent a request for follow up to the support ticket and heard nothing.  Are you aware of any updates on this?

  • David Wilkins They're certainly working on it.

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