I am sorry for bad english.
1. It's enough to have 1-4 fps in normal processing and 10fps on alarm with 720x576 or 720x288 resolution for recording.
2.This high resolution declared by the manufacturer in pixels not guarantees real high resolution.
3. With small resolutions (such as 320x200) you cant see details at all.
4. Recording of each channel in realtime - 25 (PAL), 30 (NTSC) demands a huge amount of hard disk space. One day record of 16 channels in high resolution with 25 fps per channel - it is more than 1000 Gb for most devices. One month - more than 30000Gb.
5. Recording with motion detection saves not in all cases.
6. You can't get a good quality with MPEG4, so you must use at least MPEG2.
7. Most of video capture boards works without hardware compression.
The compression is carried out by a computer. If you record a lot of video channels in real time, you need a smart computer and there is a problem with PCI bus throughput. So some hardware works fine while recording a lot of channels with small fps and there are a lot of problems in real time.
