October 19, 2021 at 3:23 pm
I’m getting Banding on walls where I’ve put a mask to knock it down via color wheels in FCPX 10.6 and was happening in 10.5. This is happening just with MP4 versions. ProRes seems fine. What am I missing?
October 19, 2021 at 3:43 pm
It’s the .mp4 file. The compression process the video signal goes through to make an .mp4 is very destructive. Modifications done in post will likely display artifacts like the one you are seeing. The compression process that creates a ProRes file is much milder. This is what makes them much more robust for modifications done during post. I liken it to the differences between a .jpg compared to a .tif file for digital photographs.
October 19, 2021 at 3:54 pm
Thanks Robert for the reply.
Is there anyway to smooth it out for an MP4? I know FCP7 had compression markers, but couldn’t find them in FCPX.
October 19, 2021 at 4:05 pm
Thank you, I’ll try it
October 23, 2021 at 11:04 am
It is likely reduced bit depth of the MP4 file vs ProRes, not the encoding compression. If the original file was even more compressed HEVC, but 10 bit 4:2:2, it likely would not happen. The root cause is 8-bit material, a dark scene, a tonal gradient and a color mask. With only 8 bits per color channel it’s easy to run out of tonal values, which then causes banding. This is worsened if the original material was shot in a flat or log profile.
The default color mask in FCP is 3D, which blends HSL selection criteria by an automatic algorithm. Cases like this can be worse if using HSL masks. However since there is more luma data than chroma data you could try and HSL mask with only Luma enabled. It probably won’t work but it’s easy to try.
Unfortunately using Neat Video can make it worse because it makes the bands crisp and more apparent. Ironically adding noise to the background can help. There’s an “Add Noise” effect in FCP.
If you have a ProRes original and after editing you want to export an MP4 for upload or distribution, you could try exporting as 10-bit HEVC. Unfortunately FCP on all hardware except Apple Silicon is very slow at that. Here is a workaround:
– Export to ProRes 422 from FCP.
– If ProRes 422 file looks OK, proceed. If not, there is a bigger problem.
– Import ProRes 422 file to Handbrake.
– Use the Handbrake video encoder labeled “H.265 10-bit (x265)”.
– In Handbrake Video tab, modify encoder preset slider: VeryFast, constant quality slider RF10. Do your own QC tests and adjust to taste. Start with small files and evaluate best combination of workflow performance and quality.
– Verify quality of local playback. If not OK, adjust Handbrake parameters and try again.
– Upload HEVC file to streaming service and evaluate playback quality. The HEVC file will be 10-bit 4:2:0, as I don’t think any NLE or tool can currently export 10-bit 4:2:2 HEVC. However it should look better than an 8-bit H264 file.
October 24, 2021 at 2:01 pm
Hi Joe, Thank you for the response,
The project was shot on the C300 MK III, in Cinema RAW Light 10-Bit.
I did use the color mask in FCP. How do I use the HSL with Luma enabled? Interested in this, the color mask is definitely the problem. The ProRes export looked fine. it was just the MP4 export and uploading to vimeo where I saw the problem.
I’ll also try your work around.
October 24, 2021 at 3:27 pm
If the ProRes export is OK, it’s probably the H264 compression plus 8-bit luma. Even though FCP 10-bit HEVC export is slow on all x86 Macs, you could export a short range to test that. The above workaround about transcoding with Handbrake is another option which is much faster for a longer timeline.
To use only luma in an HSL color mask, see this Ripple Training video:Some contents or functionalities here are not available due to your cookie preferences!
November 9, 2021 at 12:37 pm
Joe, thank you for all the information.
Giving a little up date.
I exported a very nice looking ProRes I’m happy with. Using Hand brake kept failing. So I went to compressor and simulated the same settings from Hand brake the best I could. I got a HEVC I was happy with after several attempts. The image kept getting flattened out. Once I got a good one, I uploaded it and vimeo destroyed it again, adding the banding back into the walls. I want to now try to add noise as you suggested.
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