[FFmpeg-user] Make white of photo transparant

[Cecil Westerhof]

Cecil Westerhof via ffmpeg-user <ffmpeg-user at ffmpeg.org> writes:

> Paul B Mahol <onemda at gmail.com> writes:
>
>> On Wed, Jun 29, 2022 at 10:05 AM Bouke / Videotoolshed <
>> bouke at videotoolshed.com> wrote:
>>
>>> On 29 Jun 2022, at 01:48, Cecil Westerhof via ffmpeg-user <
>>> ffmpeg-user at ffmpeg.org> wrote:
>>> >
>>> >
>>> > The background of the photo is white. Would it be possible to make
>>> > that transparent? (So where there is white, I do not see white, but
>>> > the video.)
>>>
>>> This is called Luma (or Luminance) key.
>>>
>>> Yes, it is possible, yes, it will be ugly unless you know what you are
>>> doing, and IMHO, FFmpeg is not the tool for this.
>>> (But someone recently mentioned a GUI for filters, that might help you big
>>> time on this one.)
>>>
>>>
>> Use colorkey filter, and set color as white.
>
> I will look it up.
> I realise that I have a problem, because in some photos not only the
> background is white. :'-(

I tried the following:
     ffmpeg -y -ss 21:50 -to 23:20 -i 00007-00010.MTS -i Photos/output.jpg                  \
            -filter_complex '[1:v]colorkey=0xFFFFFF\:0.01[ckout];[0:v][ckout]overlay[out]'  \
            -map '[out]'                                                                    \
            -pix_fmt yuv420p -acodec copy -vcodec libx264 -preset veryfast -crf 26          \
            -t 30 greenScreen.mp4

It really does not look that bad. (But in this photo there is no
white.)
It does take some time to be generated,

I have two challenges:
- There is no audio.
- How do I merge the two filters? (The picture should only displayed
  for a short while.)

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof