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    Le site central/maître de la ferme a besoin d’utiliser plusieurs plugins supplémentaires vis à vis des canaux pour son bon fonctionnement. le plugin Gestion de la mutualisation ; le plugin inscription3 pour gérer les inscriptions et les demandes de création d’instance de mutualisation dès l’inscription des utilisateurs ; le plugin verifier qui fournit une API de vérification des champs (utilisé par inscription3) ; le plugin champs extras v2 nécessité par inscription3 (...)

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  • FFMPEG waveform transparent, background solid color

    11 mai 2016, par user1152226

    I am trying to generate a waveform with ffmpeg, I want the background to be a solid color, and the actual waveform to be transparent. The following achieves partially what i want, except that in has a black background. I would like to be able to change this to any color, but have the waveform be transparent. How can i achieve this with ffmepg ?

    ffmpeg -i input.mp3 -filter_complex \
    
"[0:a]aformat=channel_layouts=mono,\
    
compand=gain=-6, \
    
showwavespic=s=600x120, \
    
colorchannelmixer=rr=1:gg=0:bb=0:aa=1,\
    
drawbox=x=(iw-w)/2:y=(ih-h)/2:w=iw:h=1:color=red,\
    
format=rgba,\
    
colorkey=#ff0000" \
    
-vframes 1 output.png

    This generates this waveform : the background is black, the waveform itself is transparent. How do I change the background color to a different color, while still keeping the waveform transparent ?

    enter image description here

  • FFMPEG color to transparencyq

    5 septembre 2019, par Andrew L

    I am trying to convert a mp4 video with a completely uniform pink color to a mov file seuch that the pink color is transparent.

    I have run :

    ffmpeg -i input.mp4 -vf "chromakey=0xf25b98:0.01:0" -c copy -c:v png output.mov

    I confirmed that #f25b98 is the color I am replacing. This makes absolutely nothing transparent. When I try :

    ffmpeg -i input.mp4 -vf "chromakey=0xf25b98:0.02:0" -c copy -c:v png output.mov

    I get some weird transparent dots in my pink but still nothing is changed (see attached screenshot from video).

    Why would ffmpeg exhibit this behavior ?

    output image

  • How can I use FFMPEG to extract a specific color from a video and put it over alpha ?

    28 février 2024, par Michael Macha

    I have a rendered animation which looks great, but my original file was not saved properly and has lost some of the data. I can quickly get that data back, if I can extract a specific color from the rendered video to a new file or image sequence, over either a key color or preferably transparency.

    


    Since I'm hand animating this, it's important that I automate as much as possible. I think FFMPEG could come to the rescue here and help me retrieve that data.

    


    My current line is this :

    


    ffmpeg -i ./"Light Bleeder Twirl Above.mp4" -vf "colorkey=0xe1eff9:0.1:0.1,format=rgba" -c:a copy ./out%04d.png


    


    Here, E1EFF9 is the color I'm after. It successfully extracts the handful of frames to PNG files, but it copies all of the data, not just E1EFF9.

    


    I'm not sure why colorkey isn't doing what I want it to. If someone could provide some insight, it would be much appreciated.

    


    Addendum : So, my idea worked in principle ; I did a chroma key with Kdenlive and color-to-alpha'd the black to transparency after a manual rescale. It isn't exactly the same, but it's very close and saves a lot of time. I still feel like it should most certainly have worked with FFMPEG, much faster, and would still like to know what was wrong with my script.

    


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