GStreamer1 and Device::WebIO::RaspberryPi

2014-11-22

Previous versions of Device::WebIO::RaspberryPi grabbed still images from the camera by calling out to raspistill. Given the limitations of the Rpi, this meant it had to load a program off the SD card into main memory and execute.

Meanwhile, the GStreamer framework has a plugin to read from the Rpi camera on its own. Problem was, the existing GStreamer module on CPAN was compiled against the deprecated 0.10 API, and rpicamsrc wouldn’t work against it.

I ended up asking around about 1.0 API bindings on the gtk2-perl list, and they were very patient in walking me through how to create them using Glib::Object::Introspection. Creating the bindings themselves was easy; hard part was figuring out all the magic it did behind the scenes to link to the C libraries and build Perl classes out of them.

After getting all that worked out, I released GStreamer1 on CPAN (the version number in the module name follows convention from Gtk2). Short on its heels, Device::WebIO::RaspberryPi 0.006 was released, which uses GStreamer1 to grab camera data for still images.

This greatly improves the wait time for grabbing an image in Device::WebIO::RaspberryPi. It also neatly solves a problem I’ve been struggling with since building the WumpusRover, which is that it was hard to reliably get images off the Rpi camera via Perl. With better Gst bindings, I think this is finally nailed down.