CIF

Before high-definition encoding/decoding, video conferencing data was encoded based on the Common Interchange Format (CIF). Video standards, known as H.261 and H.263, were developed by the International Telecommunications Union Telecommunication Standardization Sector (ITU-T). With the H.261 standard, only the QCIF and CIF formats were defined. The Quarter CIF (QCIF) format was applied for conferences at only the lowest data rates (64 Kbps and below) and is rarely used today. Once the H.263 standard was released, more formats (4CIF and 16CIF) were introduced with "full resolution" being defined as 16CIF. Due to the computational and bandwidth limits at the time these standards were adopted, the common resolution used for full motion video conferencing continued to be CIF to 4CIF. The following table shows corresponding format resolutions for the H.261 and H.263 standards for NTSC (North American) and PAL (European) video signals.

The resolutions listed below represent 4:3 aspect ratios.

Format

Frames Per Second

Resolution - NTSC

Resolution - PAL

QCIF

30

176 X 120

176 X 144

CIF

30

352 X 240

352 X 288

4CIF

30

708 X 480

708 X 576

16CIF

30

1408 X 960

1408 X 1152

Industry Standard Terms and Resolutions

 
H
V
HxV
Multiples
Aspect
QCIF
176
144
25,344
1/4
4:3
CIF
352
288
101,376
1
4:3
2CIF or 1/2 D1
352
576
202,752
2
4:3
4CIF/D1
704
576
405,504
4
4:3
SD - 480i
720
480
345,600
3
4:3
ED - 480p
720
480
345,600
3
4:3
HD - 720p
1280
720
921,600
9
16:9
HD - 1080i/p
1920
1080
2,073,600
20
16:9
SVGA
800
600
480,000
 
4:3
XGA
1024
768
768,432
 
4:3
 
1280
1024
1,310,720
 
4:3