Specifications
11
IDE drives, both internal. As Gyyr does not currently stock these drives, the System Integrator could order DVMS
without any Hard Drives (IDE configured). The System Integrator would source the approved drives through a
third party, and do the installation themselves.
Calculating Recording Duration/Storage Needs
Image File Sizes
An uncompressed NTSC field of video equals:
720 H. Pixels x 243 Lines x 2 bytes per pixel or 349,920 Bytes
From this we can calculate the actual file size at the 6 different compression level settings.
NTSC Field Image file size, in Bytes
Compression ratio (X:1)
10 15 20 25 30 35
Highest Quality
Lowest Quality
File Size 34,992 23,328 17,496 13,997 11,664 9998
By these figures, we can calculate how many images can be stored on a DVMS with different compression levels
and Hard drive sizes. (See Technical appendix for calculation of formulas and other minutiae)
# of NTSC Images Recorded per Hard
Drive Size
Compression ratio (X:1)
10 15 20 25 30 35
HD Size (GB)
Highest Quality
Lowest Quality
1 28,577 42,866 57,155 71,443 85,733 100,020
9 257K 385K 514K 642K 771K 901K
13 371K 557K 743K 928K 1.11M 1.30M
18 514K 771K 1.02M 1.28M 1.54M 1.80M
27 771K 1.15M 1.54M 1.92M 2.31M 2.70M
36 1.02M 1.54M 2.05M 2.57M 3.08M 3.60M
40 1.14M 1.71M 2.28M 2.85M 3.42M 4.00M
54 1.54M 2.31M 3.08M 3.85M 4.62M 5.41M
72 2.05M 3.08M 4.11M 5.14M 6.17M 7.21M
Probably the most difficult question to answer is “How long can I record using a (x size) GB drive?”. There are
many factors which affect recording time, such as recording interval, number of cameras, compression level, just
to name a few. If the desired capture rate (fields per second) matches to the first column in the chart below, you
can easily find out how many Hours per Gigabyte you can store. To use the chart, use the following 3 steps.
Otherwise, use the equations in the following paragraphs.
1) Determine the most suitable compression level setting. (See Compression Settings)
2) Determine the Fields per second recording rate desired.
3) Consult the Storage chart; Looking down the selected compression level column, find the Hours per GB
that the DVMS will record for. To calculate for specific hard drive space, multiply the # of hours times the
HD size, and you’ll get the total hours recorded for that system.