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John31956992ktyg
Participant
August 29, 2023
Question

H.264 export has random moments of low quality

  • August 29, 2023
  • 2 replies
  • 765 views

I work at a high-end video agency. We export regularly in h.264 for uploads to YouTube and the various social medias. Suddenly, premiere has started doing a very poor job exporting. At random moments, the compression will drop in quality dramatically. It usually lasts a few seconds, then goes away. It's specifically faces: macro-blocking will appear on the face to the point that you can't see any detail anymore.

 

It's not sudden. It usually fades on over a second or two, lasts 3-4 seconds, and then fades away. The issue is happening on h.264 adaptive high bitrate exports. When we export prores 422, it has no problem. It seems to only happen with .braw footage from Blackmagic Pocket 6k cameras. We use RED cameras as well, but I haven't seen the issue with those.

 

We are exporting from Premiere (version 23.5.0 build 56) and also from Media Encoder (version 23.5 build 51). Exporting from multiple Mac computers, both intel-based and M1 Mac Studios, running various OS versions, but principally Version 12.6.

 

Here are screenshots from a clip where it happens. It looks good at first, then macroblocks, then gow back to looking good. It starts on the wide (which is the Blackmagic Pocket 6k camera), but then doesn't immediately go away when we cut to the close-up (shot with the Red Helium in 8k).

    2 replies

    J
    John31956992ktygAuthor
    Participant
    August 29, 2023

    It's been with a variety of videos and export settings, and we haven't seen it change based on that. We use the Adaptive High Bitrate preset in premiere to export, usually HD (sometime UHD), 23.98fps. Here's an example of the settings we use. I understand that bitrate would be an issue, but that's why we export at High Bitrate. Why in the world would the preset for High Bitrate not have high enough bitrate for such a basic HD video export?

      mattchristensen
      mattchristensen
      Legend
      August 29, 2023

      Could you share a screenshot of your bitrate settings in the Export settings? Also what is the reported bitrate of the video in QuickTime player after it is exported, and what is the frame size/frame rate?

       

      It looks to me from your examples like the bitrate just isn't getting high enough for your particular frame size, rate, and content. Increasing the bitrate should help. Note that it's not just faces, I see it in one of your screenshots on the hands as well. This makes sense, as places that move will show macroblocking more readily than non-moving areas.

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