Artifacts when exporting mp4 'Render' tab

[user82573258]

I'm animating a PNG sequence as a 10second clip.

Part of the animation shows a clear blue sky, and I noticed there were some really bad artifacts when exporting as a mp4 / H.264 through the Render tab.

Any of the following works fine however:

1. Exporting through Media Encoder
2. Exporting as a .mov from Render tab, then compress using Handbrake

What is it about exporting as an mp4 directly through the Render tab that could cause this? Im exporting at all the default settings and see nothing relating to compression?

See the below screengrabs, with the successful export (e.g. Media Encoder) on the right:

[Thaumar]

It could be caused by the actual render and output settings you used. Can you elaborate on the settings? Like codec, bit rate, color depth. It looks like the bitrate might be set too low, and/or there are not enough encoding keyframes. 

[Rick Gerard]

You are looking at typical 8-bit artifacts on subtle gradients. There are only 256 possible shades of Red, Green, and Blue. If you rendered an 8-bit movie from the Render Queue, banding starts. Re-render that file again, and the color will be compressed again, and the banding (artifacts) will increase. Put your Media Encoder file to Handbrake or even render it using the Media Encoder, and the banding and color compression will get worse every time. That's just how 8-bit color and the color compression using blocks of 4 pixels instead of individual pixels with H.264 compression works. There is not much you can do about it except adding noise or grain to your project when you start it. 

[user82573258]

Thanks but as mentioned in my post, it looks fine when exporting through media encoder, also looks fine when compressing a .mov with Handbrake.

The problem is specifically when rending an mp4 through the Render panel

[Warren Heaton · Accepted solution]

Are you using H.264 - Match Render Settings - 5 Mbps, H.264 - Match Render Settings - 15 Mbps, or H.264 - Match Render Settings - 40 Mbps?

5 Mbps is likely to look like the image on the left or worse while 15 Mbps and 40 Mbps should look closer to the image on the right.