Transcoding UHD ProResHQ changes black level from 0 to -5mV

New Here ,
Jan 17, 2020 Jan 17, 2020

Copy link to clipboard

Copied

I mastered a film UHD DNxHR 12bit RGB in an MXFOP1a wrapper. This file passed QC. One of my deliverables is a UHD ProResHQ MOV which I made in Media Encoder 2019 on a Windows machine. It failed QC because the black levels bumped down to -5mV. It was a small enough difference that I couldn't see on the hardware scope without zooming in. Also the SMPTE bars & gamma appeared identical. But pure black is down at -5mV.

(This is not a full range/video levels issue, -5mV is tiny.)

Oddly, if I make an 1080 HD ProRes in MediaEncoder from this same file, there's no issue, black at 0mV.

To test if the problem was the input codec I made mezzanine files DNxHR 10bit YUV & Cineform but the resulting UHD PR HQ has same -5mV issue.

If I turn off "Render at Maximum Depth" the black levels issue goes away, black is at 0mV, but cannot use this file because the quality is reduced (visible noise/banding)

Upgraded to Media Encoder 2020 & results are same.

Then I tried this on a MacOS Media Encoder & got the same -5mV result in the UHD HQ (very strange)

I then made the UHD ProRes HQ in Assimilate Scratch & the ProResHQ was identical to the source & passed QC, all black levels at 0mV.

Haven't located anyone else reporting this issue but would like to use Media Encoder for ProRes delivery in the future.

 
TOPICS
Error or problem, Export or render, Formats

Views

141

Likes

translate

Translate

Translate

Report

Report
Community Guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
community guidelines
no replies

Have something to add?

Join the conversation