Hey Ralph,
My personal preference on my PC is to avoid H264 at all costs, particularly if it’s done through Apple QT codec – however, sometimes that can’t be helped.
Nevertheless, as someone suggested on the Adobe forum, it may be that your footage already have artifacts in it, that is being exposed through re-encoding it.
My initial suggestion would be to do an uncompressed export and compare that with the original. If it doesn’t happen there, then it is your H264 settings that you need to work on.
The other thing to try is to turn off
“Render at maximum depth”
&
“Use Maximum Render Quality”
as you are already working compressed and you are not currently adding any graphics or fx to the video, I see no advantage in having those boxes ticked – if anything, it by trying to make it too beautiful, this may be the reason for the artifacts coming out.
Although it doesn’t give you 60fps, have you run a test through the “H.264 Blu-ray” codec also included with PPro?
It is all about finding an output that gives you a minimum of artifacts, whilst being close to your desired result. Do keep mind though out that you are re-encoding already compressed footage, and that it will never improve – unless you use specific software to remove the “noise” with, but even that is not always perfect depending on your final method of distribution.
All the Best
Mads
@madsvid, London, UK
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https://mads-thinkingoutloud.blogspot.co.uk