[FFmpeg-user] Selecting colors of the waveform

[Marcin Borkowski]

On 2023-03-08, at 19:15, Michael Koch <astroelectronic at t-online.de> wrote:

> Am 08.03.2023 um 18:48 schrieb Marcin Borkowski:
>> Hi all,
>>
>> I'm fairly new to ffmpeg, so sorry, if this is something obvious.  (I'd
>> also appreciate any pointers to the docs - I haven't read them all, of
>> course, but I _did_ try to find the answer to my questions there.)
>>
>> I know that I can create a bitmap with the waveform of a selected part
>> of a media file and send it to stdout like this:
>>
>> ffmpeg -ss 00:10 -to 00:11 -i file.mp4 -filter_complex showwavespic=s=600x40 -frames:v 1 -f image2 -
>>
>> Now the question is, how do I change the colors (background and
>> foreground)?  I already know about `:colors=white' for the foreground,
>> but how about the background?
>
> It seems this filter has no option for changing the black background.
> If you need white background, you could simply invert the output video 
> with "negate" filter.
> For other colors you could use a workaround with "colorkey" and 
> "overlay" filters.

Thanks.  I used `showwavespic=s=600x40:colors=white,negate` which
helped, though now I can't really change the _white_ background to
e.g. light grey;-).  I think I'll not try to use `overlay` -- the docs
imply that it is a bit too complex for a beginner like me -- and I'll
just use ImageMagick for that.

Best,

-- 
Marcin Borkowski
http://mbork.pl