Those nice boxes have multiple video inputs, serial/RS485/parallel i/o for alarms, camera motion etc, one or more audio i/o, HDMI output, one or more SATA ports, etc and some cost down to less than $50 including case, power supply, cables, mouse and remote. And all of them run Linux. The logical question is: did anyone manage to flash some embedded distro on one of these boxes to extend their capabilities or use them for different purposes? 4 or more channels video sampling means they use some pretty fast ADCs in there.
Here's one.
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Having placed a few of them I can confirm, regardless of their brand/model, many use the same firmware save for a few changes.