[FFmpeg-user] Fluorescent White Balance Video Filters

[Michael Koch]

Am 21.04.2022 um 04:25 schrieb Roger:
> ...
>> You can make your own LUT, as described in chapter 2.28 in my book.
>> -- Extract one frame from your video.
>> -- Insert a haldclut in a corner of the image, or use xstack to attach it to
>> the side.
>> -- Use the program of your choice to correct the colors in this image. When
>> done, save it lossless as 16-bit PNG.
>> -- Use FFmpeg to separate the haldclut from the image.
>> -- Apply the LUT to the whole video.
>>
>> Michael
> Sorry.  I had a little difficulty with understanding the text within the
> Chapter 2.28.  Just couldn't scan and understand easily.  Although I thoroughly
> understand SH/Bash, the variable assignments for simple filenames also slowed
> reading, as I had to scan/reference back to the top of the page for the
> definition/intent of the variable used.  Easier understanding for the reader to
> read, "input_video.ext" and "output_video.ext", or use a similar named variable
> such as $_input_video.ext and $_output_video.ext. Note: using a prefixed
> underscore within SH/Bash variables separates/isolates from any possible
> conflicts.  Heard of using this syntax from the Bash mailing list when doing C
> style defines in SH/Bash.  However, for the sake of easy readability for
> readers, it's probably best to use simple non-isolated variables.

My examples are for Windows batch files. For example, the line

set "IN=P100.mov"

sets the variable IN to the value P100.mov

If this variable is used in the command line, for example

ffmpeg -i %IN% -vf crop=...

then %IN% will be replaced by the filename, so that the command line for 
ffmpeg becomes

ffmpeg -i P100.mov -vf crop=...

Michael