This is a speciality inherited from television technology. If it didn’t happen, then, due to movements/motions, there would be an interlace appearing on the recorded image, which may significantly worsen the recognizability. This way, the image of a 51o-line resolution analogue camera is altogether a 255 pixel resolution vertically when digitally recorded. There are different techniques to maintain the size of the recorded image, but they wouldn’t change the resolution of the image recorded.
Therefore, high resolution analogue cameras do not comply with the regulations of security technology when recording images.

The solution is to use analogue progressive scan cameras or digital cameras, because they record the right resolution image during digital recording.

In the former case, the problem may be more complex, because we need a digital recorder that can process the image of progressive scan cameras. There are only few recorders like that in commercial trade. On the other hand, the maximum resolution is 525 lines due to television technology, which we cannot exceed.

Digital cameras may go far beyond due to direct digital recording. The vertical resolution of the currently available simplest cameras is 480 pixel, but full HD (1920x1080) resolution cameras are also available.

Prices vary, traditional analogue cameras cost one third of the simplest digital cameras, while progressive scan cameras cost hardly less. Bear in mind, that process (digitalization) of images of analogue cameras entail further costs (digital conversion card), which is unnecessary in case of digital cameras.

that operation of a digital camera does not require extra power supply voltage and wiring for image forwarding?

The majority of digital cameras is capable of receiving the necessary power supply voltage through the wire used for digital image forwarding (PoE). This has almost only advantages, since the central uninterrupted power supply of cameras and the recorder is available and the disturbances on distant camera images no longer occur, no need for groung loop separator. Its only disadvantage is the distance limit of 1oo metres, which though can be doubled by inserting a switch at minimum cost, that also serves for distant supply. Thus, service remains reliable.

that there are free digital video recording softwares?


In reality, we call these open source code softwares and their reliability is well known. Only few people know these, although their services reach, and in some cases exceed, that of softwares available on the market. They are compatible with several manufacturers’ products.

Its historic cost, besides hardware, is just costs of installation and configuration, as these softwares are free indeed for business purposes as well. Their maintenance need is minimal, although require an expert.