This is the spec sheet from the one that gave the formula above
ITEM DESCRIPTION NOTE
Video Format NTSC / PAL
Operation System STAND ALONE
Camera Input Channel 4 channel Composite BNC
Video Output Channel
2 channel Composite BNC
USB 2.0 Port
NTSC 120 frames 4 x 30 frames
Display Frame Rate
PAL 100 frames 4 x 25 frames
Recording Frame Rate NTSC Max 30 fps (Quad) Quad Mode
(Quad) PAL Max.25 fps (Quad) Quad Mode
NTSC
Each Channel =
30 / Number of Source(frames)
Max. 30 frames
Recording Frame Rate (Each Channel)
(Each Mode)
PAL
Each Channel =
25/ Number of Source(frames)
Max. 25 frames
(Each Channel)
Record Modes
Continuous, Schedule, Motion
Triggered , Sensor Triggered
Display
NTSC 720 x 480
PAL 720 x 576
Resolution
Record
NTSC 320 x 112, 640 x 224
PAL 320 x 136, 640 x 272
Quad 640 x 224 (total)
Each 640 x 224
Video Compression Format
(Each Channel)
Modified Motion-JPEG
(12-20K bytes/frame)
Low :12K Byte
Normal :15K Byte
High : 20K Byte
HDD Support 200G Byte ATA -100 Interface
Estimated Record Length
80G Hard disk @ 7 fames per second @ Normal Quality
(80*1024*1024 K byte) / ( 7*15*60*60 ) = 222 Hours
Method Time, Date, Event
Search
Full Screen YES
Sensor, Alarm
4 Inputs (Normally Open / Normally Closed)
1 Output (Relay contacts rated 2A @28VDC )
Camera Signal Loss Alarm
PTZ RS-485
Dimensions Length 315mm * Width 224mm * Height 52mm