Compressor 5.2: Blocky artefacts in multi-pass H.265 HEVC

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Level 1

45 points

Compressor 5.2: Blocky artefacts in multi-pass H.265 HEVC

Unless I deselect "multi-pass" in the quality settings, Compressor 5.2 is consistently giving very blocky compression artefacts on 4K25 HEVC (H.265) Rec.2020 exports:

The compression artifacts (to use the US spelling) last about 2 seconds.

Based on other posts I've removed all markers such as chapters to avoid breaking the codec but it still happens. There is no common thread about where it occcurs in each project (eg. difficult-to-compress scenes) which means I have to watch every export from beginning to finish – or deselect multipass, which is not optimal.

I've reported it before (the bug's been around for at least a year) but no fixes. Any other thoughts please?

(On a footnote ... it took me ~3 minutes to actually get into the compressor/ask a question community page, ... soooo many time-wasting dead ends on Apple's site these days ... and when I get here it doesn't accept apple's own heif images and wastes time & energy to give me a dodgy AI title... think I'll stick to CreativeCow in future!)

MacBook Pro 16″

Posted on May 29, 2026 9:22 AM

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Answer 1

May 29, 2026 9:30 AM in response to Adam Sebire

I haven't tried such an export, and will probably only be able to try one tomorrow.

OTOH, I am puzzled by your comment about how difficult it was to post. I don't see what is the problem there.

I opened the Compressor page, typed something like "Artifacts when exporting H265"

and it took maybe 5 seconds searching, then it presented with an "Ask the community" button.

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Answer 2

Adam Sebire Author

Level 1

45 points

May 29, 2026 10:13 AM in response to Luis Sequeira1

Well, sure enough, now that I try to replicate the (many) problems I had with getting to this forum the "ask the community" button does now appear under the results. Earlier, A Funny Thing Happened on the Way to the Forum... (Sondheim joke).

So you're right, Luis, sorry.

Anyway... I'm not sure you'll be able to replicate it as it may be a very specific combination of, for example, PAL and HLG, but here are my settings with multi-pass deselected to get an export sans artefacts.

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