compression artifacts in video and bitrates

Started 3 months ago | Discussions thread
Lee Jay Forum Pro • Posts: 56,673
Re: compression artifacts in video and bitrates
1

markyboy81 wrote:

I shot some video of my family in fairly heavy snowfall yesterday - it was 4k 25fps at 80mbps HEVC.

Usually when I edit the video (only making minor adjustments and combining clips) I find that if I output to around 14mbps QHD using the h264 codec (unfortunately no HEVC available) the result is pretty good with no artifacts.

I'm wondering if the snowfall somehow caused the low bitrate to not be able to cope as there were lots of artifacts in my son's face at the 14mpbs bitrate?

Absolutely.

I tried increasing it and it improved a little bit at 30mpbs but still nowhere near the original.

Could the snowfall have caused these issues?

Yes.

There were also some issues with the autofocus as I guess the big flakes of snow confused the system. Are there any other scenarios to be aware of when considering what bitrate to output the video to? I know fast movement is one, wondered whether there were any others.

The bit rate you need to faithfully reproduce video is *incredibly* sensitive to how much change there is between frames in the video.  Mostly static - 3Mbps might be enough.  Very noisy and lots of motion - 80Mbps might not be enough.

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