ffmpeg: How can I convert from H.265 into another 10bit format for colour grading?

Question

I am very new to dealing with video, so apologies if this is a completely inane question: I was wondering if you could advise me on how to transcode 10bit H.265 All-I 4k footage into some other 10bit format for the purposes of colour grading in Davinci Resolve? I am using the free edition of the software, which does not support H.265. H.265 is also exceedingly tough on my CPU, which I didn't think about when buying a 4k video camera!

I am on Windows. It looks like it would need to be some variant of DNxHR, but I get completely(!) lost trying to construct the terminal commands to make the conversion.

Here is a very short video in the format that I need to transcode from:

drive.google.com/file/d/1MLaXKDzwaZvbVBp2rlyf7SfxReVbcxID/view

I'd be really grateful if you could help me out with this!

Answer 1

I'm not familiar with DaVinci Resolve, but if the free version supports 10-bit H.264 you can use HandBrake to transcode to that format with CRF 0 and see if that works.

If that doesn't work you'll need to use FFmpeg. With a bit of fiddling I was able to convert your source file to DNxHR using this command:

ffmpeg -i DSCF1265.MOV -c:v dnxhd -profile:v dnxhr_hqx -color_range 2 -c:a copy DSCF1265.dnxhr_hqx.mov

This also copies the audio over, if you want to exclude it for some reason use -an instead of -c:a copy.

The -color_range 2 bit is important, without it the output looked different from the input (at least when watched with mpv).

Answer 2

Sorry, just missed out on free version of resolve..

For conversion you gotta use ffmpeg. I'm afraid that's the only solution I can think of right now.

CONVERT H. 265 encoding 4:2:2 in 10-bit with libx264

If your system cannot handle it, try using a proxy workflow or the optimized media. It converts the file internally.. Check out this tutorial for furthermore

Answer 3

This answer builds on the one above by veikk0 with some thoughts on how this can be incorporated into a more automated workflow.

You can automate this using a windows batch file. Create a new text file with Notepad or your preferred text editor and include the following

+@echo off
set currentPath=%~dp0
set targetPath=%~dp0
:Loop
echo "%~1"
IF "%~1"=="" GOTO Continue

"%currentPath%ffmpeg.exe" -i "%~1" -c:v dnxhd -profile:v dnxhr_hqx -color_range 2 -c:a copy "%targetPath%%~n1dnxhr_hqx.mov"

SHIFT
GOTO Loop
:Continue
pause

Save the file as 10bitTranscode.BAT in the same folder as your ffmpeg.exe

Now open the windows Run dialog (windows key + R) and run shell:sendto . This will open the Windows SendTo folder. Create a shortcut to your .BAT file in this folder (by right-click dragging the bat file over to the SendTo folder and selecting 'Create shortcut here' from the menu that appears).

Now you should be able to select a whole bunch of clips in File Explorer, right click on them, and select SendTo > 10bitTranscode.BAT and windows will automatically batch transcode all of them in sequence.

By default the outputted files will be saved in the same folder as ffmpeg, but you can have the output written to a different folder by editing the set targetpath= line in the code above to set targetpath="<your desired output path without trailing \>".