Banding with h264 and tried everything to remove it

[ML72]

Hi all

I am trying to get a film ready for festival presentation where the accepted format is a h264/MP4 file @25mb/s. The problem is my very first opening shot has a slow cross dissolve/fade in. For some reason I am getting terrible banding which spreads out to the corners like ripples in a pond and looks like utter crap.

Example:

I have absolutely no idea why it's doing this. This is on ungraded footage which was recorded in Proress 444 recorded at 12bits.

I've tried everything from turning off GPU, maximum render quality, maxium bit depth, adding noise you name it, but nothing works.

Is this a limitation of h264? If so what can I do to avoid this (except from a hard cut in)?

Thanks!

[chrisw44157881]

first render out as a qucktime png(8 bit forced dither), import that one back in and use neatvideo to remove banding, then finally export as h.264. its a limitation of 8 bit, so you have to smart luma/chroma dither with neatvideo after first dithering from 10 bit to 8 bit. tricky, huh?

[ML72]

Thanks. Not tricky at all, but I tried that but do not see a forced dither option for Quicktime PNG. So I just chose standard 8bit output and re-imported into my project. I added Neat Video but it just made it worse. The more NR I added the bigger the ripples got. I added grain on top to be sure but it makes zero difference.

Tell a lie, it made the bands larger.

Cheers.

[chrisw44157881]

do the bands get worse after 8 bit export or just after neatvideo? also, are you rendering max quality in ame? are you customizing neatvideo or just applying it as default? btw, neatvideo does not make banding worse, so you must be doing something it doesn't like. and increase your h.264 bitrate.

[David Arbor]

Since you're limited to 25 Mbps, I'd recommend trying x.264, the open source and better implementation of h.264. Handbrake supports this, and you'll find that you can use a much lower bit rate and retain quality compared to the similar bit rate with the MainConcept h.264 encoder that ships with Adobe products. The benefit here is that a 25 Mbps x.264 file should be significantly higher quality than your current 25 Mbps file.