2020-09-29 19:41:53 +11:00
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% nouveau juillet 2014 à mixart-myrys
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\chapter{Webcam}
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2020-11-02 05:32:45 +11:00
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\label{chap:webcam}
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2020-09-29 19:41:53 +11:00
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\index{webcam}
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2020-11-03 09:08:45 +11:00
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Sous Linux, c'est quand même un peu tordu%
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\footnote{Avis personnel !}, dans le même genre
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que la pile son, quoi...
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Nous allonc commencer par les principes et outils
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de base, puis passer à plus
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2020-09-29 19:41:53 +11:00
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simple : juste tenter de prendre une photo avec une
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\textsl{webcam} classique en USB, et d'enregistrer cette
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image.
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2020-11-02 05:32:45 +11:00
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\section{v4l2}\index{v4l2}
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\textsl{Video For Linux, second edition.}
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2020-11-03 09:08:45 +11:00
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\begin{verbatim}
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tth@delirium:~/Essais/Fonderie$ v4l2-ctl --list-formats-ext
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ioctl: VIDIOC_ENUM_FMT
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Type: Video Capture
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[0]: 'MJPG' (Motion-JPEG, compressed)
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Size: Discrete 640x480
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Interval: Discrete 0.033s (30.000 fps)
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Size: Discrete 320x240
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Interval: Discrete 0.033s (30.000 fps)
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Size: Discrete 1920x1080
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Interval: Discrete 0.033s (30.000 fps)
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Size: Discrete 1280x720
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Interval: Discrete 0.033s (30.000 fps)
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\end{verbatim}
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2020-11-10 12:40:30 +11:00
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Question : quelle méthode utiliser pour avoir la même chose avec
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2023-10-09 06:56:41 +11:00
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des lignes de code écrites en C ? Il faut passer par une suite d'appels
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\texttt{ioctl}\index{ioctl}.
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2020-11-10 12:40:30 +11:00
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2020-11-02 05:32:45 +11:00
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2020-09-29 19:41:53 +11:00
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\section{vgrabbj}
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\index{vgrabbj}
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2020-11-10 12:40:30 +11:00
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2020-09-29 19:41:53 +11:00
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D'après la manpage :
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« \textit{
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vgrabbj is a program that will grab images from any v4l-capable device
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which supports one of the rgb24, rgb32, yuv420, yuv420p, yuyv, or
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yuv422 palettes and saves the image as a .jpg, .png, or .pnm file.
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} »
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Quelques options à connaitre : \texttt{-S} échange des
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deux composantes R et B; \texttt{-s <device>} affiche
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les capacités du périphérique v4l\index{v4l}.
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% --------------------------------------------------------------------
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2020-11-03 09:08:45 +11:00
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\section{Cheese}
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\begin{quote}
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cheese uses your webcam to take photos and videos, applies fancy special
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effects and lets you share the fun with others. It was written as part of
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Google's 2007 Summer of Code lead by daniel g. siegel and mentored by Raphaël
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Slinckx. Under the hood, Cheese uses GStreamer to apply fancy effects to photos
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and videos. With Cheese it is easy to take photos of you, your friends, pets or
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whatever you want and share them with others. After the success of the Summer
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of Code, the development continued and we are still looking for people with
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nice ideas and patches ;)
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\end{quote}
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2020-09-29 19:41:53 +11:00
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% --------------------------------------------------------------------
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2021-10-05 07:24:01 +11:00
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\section{Kinect} \index{Kinect}
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Bon, voilà un nouveau gadget ;)
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À priori, la partie caméra RGB est gérée classiquement par v4l2,
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mais le coté spécifique, je ne sais pas qu'en faire...
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