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%    nouveau juillet 2014 à mixart-myrys
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\chapter{Webcam}
\label{chap:webcam}
\index{webcam}

Sous Linux, c'est quand même un peu tordu%
\footnote{Avis personnel !}, dans le même genre
que la pile son, quoi...
Nous allonc commencer par les principes et outils
de base, puis passer à plus
simple : juste tenter de prendre une photo avec une
\textsl{webcam} classique en USB, et d'enregistrer cette
image.

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\section{v4l2}\index{v4l2}

\textsl{Video For Linux, second edition.}

\begin{verbatim}
tth@delirium:~/Essais/Fonderie$ v4l2-ctl --list-formats-ext
ioctl: VIDIOC_ENUM_FMT
        Type: Video Capture

        [0]: 'MJPG' (Motion-JPEG, compressed)
                Size: Discrete 640x480
                        Interval: Discrete 0.033s (30.000 fps)
                Size: Discrete 320x240
                        Interval: Discrete 0.033s (30.000 fps)
                Size: Discrete 1920x1080
                        Interval: Discrete 0.033s (30.000 fps)
                Size: Discrete 1280x720
                        Interval: Discrete 0.033s (30.000 fps)
\end{verbatim}

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\section{vgrabbj}
\index{vgrabbj}

D'après la manpage : 
« \textit{
vgrabbj  is a program that will grab images from any v4l-capable device
which supports one of the  rgb24,  rgb32,  yuv420,  yuv420p,  yuyv,  or
yuv422 palettes and saves the image as a .jpg, .png, or .pnm file.
} »

Quelques options à connaitre : \texttt{-S} échange des
deux composantes R et B; \texttt{-s <device>} affiche
les capacités du périphérique v4l\index{v4l}.


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\section{Cheese}

\begin{quote}
cheese uses your webcam to take photos and videos, applies fancy special
effects and lets you share the fun with others. It was written as part of
Google's 2007 Summer of Code lead by daniel g. siegel and mentored by Raphaël
Slinckx. Under the hood, Cheese uses GStreamer to apply fancy effects to photos
and videos. With Cheese it is easy to take photos of you, your friends, pets or
whatever you want and share them with others. After the success of the Summer
of Code, the development continued and we are still looking for people with
 nice ideas and patches ;)
\end{quote}

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