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Intermediate CODEC question

PostPosted: Tue Jan 29, 2019 6:00 pm
by Joshua_G
When the source material is 1080 25p 4:2:0 8bit h.264 and the delivery is the same, is there any benefit by using intermediate CODEC of 4:2:2 and/or 10bit for the sake of better color correction/grading?

Re: Intermediate CODEC question

PostPosted: Thu Jan 31, 2019 10:49 am
by antoine
Yes of course ! You can have different formats/containers/codecs/specs for capture, intermediate (post production) and final diffusion but you need to understand what your hardware and software stack is doing at every step and why you would need better quality.

For example if you do "8 bpc input -> multiple color grading in 8 bpc -> 8 bpc" output you can have weird artifact popping up and doing "8 bpc input -> multiple color grading in 16 bpc -> 8 bpc" instead can remove them. All depends on your actual content / editing / special effects of course.

Re: Intermediate CODEC question

PostPosted: Thu Jan 31, 2019 1:59 pm
by Andrew Kolakowski
Joshua is asking if there is any difference in having 8bit source converted to 10bit intermediate file vs. using original 8bit. Not a difference between 8 vs 10bit real source.
Answer is- no. Your 10bit intermediate file will hold same usable 8bit data. There is no magic (until you use some spacial tool which would try to increase bit depth, which is not easy).
Only difference is that intermediate codecs will make your editing smoother as they are way less compressed and easier to decode (and I frame based). When it comes to usable data for grading it won't give you anything above your original source.
10$ is 10$ regardless if you have it in big wallet or small one :D

Re: Intermediate CODEC question

PostPosted: Fri Feb 01, 2019 11:52 am
by Joshua_G
Thanks, Antoine and Andrew.

Re: Intermediate CODEC question

PostPosted: Mon Feb 04, 2019 11:30 pm
by David Baud
Another consideration is the software you use for color correction: the internal operations need to happen in higher bit-depth if you don’t want to introduce any new artifacts especially with 8-bit footage during decode/encode. Many modern software like DaVinci will operate in 32-bit floating point, so you should not to worry working with lower bit footage in terms of image quality.


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Re: Intermediate CODEC question

PostPosted: Tue Feb 05, 2019 10:34 am
by Joshua_G
Thanks, David.
I use DaVinci Resolve for both editing and color correction/grading.

Re: Intermediate CODEC question

PostPosted: Sat Feb 09, 2019 5:49 am
by antoine
Andrew Kolakowski wrote:Joshua is asking if there is any difference in having 8bit source converted to 10bit intermediate file vs. using original 8bit. Not a difference between 8 vs 10bit real source.
Answer is- no.

The answer is "it depends" -- cf. David's answer and mine

Andrew Kolakowski wrote:Your 10bit intermediate file will hold same usable 8bit data. There is no magic

The magic comes from the fact that you loose quality each time you store the results of an operation on the data. If your logic was true then filmmakers could shoot in 8 bpc, edit and grade in 8bpc and have a great 8 bpc output...

Re: Intermediate CODEC question

PostPosted: Sat Feb 09, 2019 12:10 pm
by Andrew Kolakowski
Looks like you don't really understand original question. It's not about shooting 8bit vs 10bit (or editing/grading in higher than source bit depth), but about converting 8bit source into 10bit in hope for gaining usable data during this process.

Resolve will convert any source to 32bit float straight after decoding. So if you have 8bit file or previously converted 8bit to 10bit your usable data in Resolve will be the same and end results as well. Where does "your magic" happens here? Where will Resolve find more data in this 10bit source (coming from 8bit) file compared to original 8bit? In many cases it's same date with padding zeros (in others just converted 8bit into 10bit, which adds nothing new/usable). It's plain math. In order to get something more you need to have advanced algorithm added to bit depth conversion process, but not a single common tool does such a thing. There are some open source tools for this, but this is very specific topic.
10$ is 10$ regardless if it's in small or big wallet :)

Re: Intermediate CODEC question

PostPosted: Sun Feb 10, 2019 10:29 am
by Joshua_G
Thanks, Andrew.
Andrew Kolakowski wrote: … In order to get something more you need to have advanced algorithm added to bit depth conversion process, but not a single common tool does such a thing. There are some open source tools for this, but this is very specific topic. …

What are those open source tools?

Re: Intermediate CODEC question

PostPosted: Sun Feb 10, 2019 1:52 pm
by Andrew Kolakowski
avisynth, vapoursynth with filters GradFun3, f3kdb 2.0, dither tools etc. Those filters can remove banding quite well in some cases (= increased bit depth), but when you encode to low bitrate then banding will be back. I don't think it's worth the hassle until you really have special case (eg 8bit source footage which needs to go to high quality end master).

Re: Intermediate CODEC question

PostPosted: Mon Feb 11, 2019 10:19 am
by Joshua_G
Thanks, Andrew.