Does re-rendering an mp4 or mov (H264/5) cause quality degradation?

[Traderbam]

I'm showing my lack of knowledge here so this might be a daft one.

I'm processing a lot of old tapes, capturing to Huffyuv AVI, deinterlacing to ProRes, then importing to Resolve. Some of the files end up on YT or social media so I'm using MOV(H265) files for my output.

I sometimes include watermarks/logos on the clips, but if I were to rebrand, it seems a huge pain to have to go through all the source files again, deinterlace again, and re-render from Resolve.

I'm thinking that it might be better idea to render out a version for YT with no watermarks/titles/logos initially, and if I need to add anything later I can simply import that H265 MOV file to Resolve, add the 'current version' of my branding/logos and output the file.

Will I lose quality if I import the MOV file, add a logo/watermark and re-render in Resolve, or are only the modified pixels changed?

Edit: Part of the motivation here is to remove the requirement to keep my source Huffyuv AVIs long term due to massive file sizes.

[Sharc]

Will I lose quality if I import the MOV file, add a logo/watermark and re-render in Resolve ...

Yes. Every re-encode reduces quality (deviations from the original = artifacts). Question is how much you tolerate. You decide.

[Traderbam]

Thanks. Is there anything specific to H265 that would result in lower loss than say a different codec? Typically for my YT uploads I output from Resolve at the highest quality (something like 25000kbps bitrate) which is probably overkill but I'm thinking if the bit rate is already higher than YT expects, would a re-render really impact that much.

[Dooby]

No, it is not possible, unless you use the original video capture material and include the logo from the beginning. Rendering two copies, one with the logo, one without is your best option (in my opinion) but for youtube, don't they re-encode uploads anyway? Your original capture material is the best source you have to work from should you ever want to alter or amend things in the future. They are the last things to dispense with, surely?

TeraBox give you a terabyte of free storage. Upload the youtube versions you create there and you haven't any storage problems.

Shutter Encoder claims to do some non-destructive things, but I have my doubts.

[pandy]

Yes. Every re-encode reduces quality (deviations from the original = artifacts).

https://forum.videohelp.com/threads/417471-Convert-H265-to-H264-losslessly