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Hammel, 15 Nov 2019 14:02

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h1. Camera
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_This is only in the idea stage.  No development on this has started._
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Making remote camera controlled by Ironman has been an interesting problem.  Many solutions use Arduinos.  But then I ran across an interesting idea using a "RPi Zero W set inside a dummy camera housing":https://youtu.be/H7p5YEOrlSc.  That led me to think about how I can use PiBox directly instead of using an Arduino based solution.
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table{align=center}.
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|!{width:640px}ironman-camera.png!|
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|={font-size:120%;margin-bottom:15px;background-color:#dff}. *High Level Camera Design* |
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The camera is based on a RPi Zero W running a new _{color:blue}PiBox Lite_ release (PiBox stripped of X and other unnecessary components).  A web API is built using "Mongoose":https://github.com/cesanta/mongoose (web server written in C and easily extendable) (or "original source":https://storage.googleapis.com/google-code-archive-source/v2/code.google.com/mongoose/source-archive.zip) that basically just starts up mjpeg-streamer just as the PiCam app current does.  mjpeg-streamer provides a URL that the monitor will access.
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The mongoose server is used to reduce overhead - mongoose is self contained and doesn't need a bunch of libraries.  On the flip side, "nodejs":https://nodejs.org/en/ with "restify":http://restify.com/ (for a REST API) is easy to implement but carries lots of weight (as all scripting languages do) and would require an external programs for running some components.  
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The camera doesn't need to run full time.  We can attach a "PIR sensor":https://www.mysensors.org/build/motion to a GPIO and wake the camera then.  The definition of "wake" is critical:  if it takes mjpeg_streamer too long to start up and start acquiring video then we miss the image we want to capture.  If we run mjpeg_streamer all the time then we use too much power.  So the PIR has to be able to start recording but mjpeg_streamer needs to start acquiring video quickly.  An alternative to this may be to have ffmpeg handle video capture if mjpeg_streamer takes too long to start.  Note that piboxd normally starts mjpeg_streamer and there may be a lag between getting the GPIO notification from the PIR and sending the request to piboxd.  Hopefully the recent updates to thread synchronization will help speed this up.
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The monitor is the standard Ironman Monitor with the addition of a new app: IMCameras.  This is based on PiCam but supports selection of which camera to visually monitor.  It also supports the following commands issued to selected monitors.
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* Start recording
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* Stop recording
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* Play a recording
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* Live view
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A stretch goal is to allow display of up to four cameras at once.  This would work only if omxplayer can be convinced to display only into a subsection of the framebuffer.  Alternatively, a "different player with hardware acceleration":https://www.raspberrypi.org/forums/viewtopic.php?t=199775 might be found, such as "mpv":https://mpv.io/.
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The monitor would need extending to support storage, possibly using a new Ironman storage device that connects via Samba or NFS.