Video Resolution And Compression Standards - GE Security Legend IP Installation Manual

Video resolution and compression standards

Video resolution and compression standards affect video quality, file size, and storage requirements. Table 7
and Table 8 outline the video and compression standards that are available with Legend IP and SymSuite
products. Program your system with the standards that will best meet your overall surveillance needs.
Video resolution standards
The NTSC and PAL video signal standards (Table 7) have the same data transmission rates at the same
resolutions. NTSC's higher frame rate is offset by PAL's higher vertical resolution. Briefly, analog video
signals are interlaced, meaning each picture consists of two fields of half-pictures. NTSC video consists of 60
half-pictures per second, while PAL video consists of 50 half-pictures per second. This translates to 30 fps
(frames per second) for NTSC and 25 fps for PAL in terms of noninterlaced (or progressive scan) digital video.
Table 7. Video resolution standards available with Legend IP domes and SymSuite products
Video resolution
standard NTSC (60 Hz)
D1 720 x 480
4CIF 704 x 480
2CIF 704 x 240
CIF 360 x 240
QCIF 180 x 120
QQCIF 88 x 60
Video compression standards and data rates
When considering the overall data rate of how fast the video travels through your surveillance system, you need
to consider the speed of the chosen video resolution standard and the speed of your network connection
(Table 8). For instance, if you choose to use the CIF video resolution standard, which transmits at an
uncompressed data rate of 61 Mbps (Megabits per second), your network connection needs to be at least an
OC3 line, because the T3 line only transmits up to a data rate of 45 Mbps. For details about digital video
compression standards, such as MPEG-4 and Wavelet, refer to the Compression standards section of the
SymSecure System Guide (1055580).
Table 8. Comparison between video and network data rates
Video resolution
standard uncompressed data rate (Mbps)
D1
4CIF
2CIF
CIF
QCIF
QQCIF
PAL (50 Hz)
720 x 576
704 x 576
704 x 288
360 x 288
180 x 144
88 x 72
Video speed as
249
244
122
61
16
4
Supported by Legend IP
domes
X
X
X
Network connection
Dial-up
Cable modem upchannel
DSL
T1 line
T3 line
OC3 line
OC12 line
OC48 line
OC192 line
Chapter 1
Introduction
Supported by SymSuite
products
X
X
X
Network speed as
transmission data rate (Mbps)
0.04
0.25
0.50
1.54
45.00
155.00
622.00
2560.00
9830.40
15