There is such piece of iron — QQIP DVR DI. USB videozakhvat for analog cameras, 4 channel.
Under Windows it works, but only from a native app. In the system a piece of iron is seen as one device — USB Serial Converter (id 0403:6014). And I need each channel was a separate device so they can be treated by standard means. And most importantly — to Linux worked, i.e. that there were four device /dev/video[1-4] (or one device with four channels hw:0-3).
Poked a USB sniffer, it turned out that all four streams are alternately in one common stream with the device, but a native app as it resolves. Description of the Protocol no SDK, no nothing :-)
Note the question — who is faced with? Can something advise about the support of this animal in Linux? Or just tell me pliz, any other device for capture (at least 4 channel is necessary) to connect via USB and normally see in Linux. EasyCap is like there, but there are people arguing that when several channels are active, lag badly and Altima does not smell.
UPD> More picking pieces of iron here, a census will not, if you are interested in more detail — is in blozhike