Common Intermediate Format
The Common Intermediate Format ( CIF ) was introduced by the International Telecommunication Union (ITU) in the video conference standard H.261 because the two video standards NTSC and PAL have different resolutions and frame rates. This gave rise to compatibility problems when a video conference was to be set up from an NTSC-based monitor and camera to a PAL-based monitor and camera.
This is an intermediate format where NTSC and PAL meet halfway, using the greater spatial resolution of PAL and the greater temporal resolution of NTSC. All lengths and widths are even multiples of 16 pixels. The CIF pixels are not square and must therefore not be compared directly with computer pixels.
- SIF NTSC = 352 × 240 @ 30 Hz
- —Spatial →
- CIF = 352 × 288 @ 30 Hz
- ← temporal—
- SIF PAL = 352 × 288 @ 25 Hz
QCIF stands for Quarter CIF . Along with CIF, this is the most common format in video coding. "Quarter" means that the image area is quartered, that is, the height and width are halved.
The table on the right shows the most common formats for video resolutions by name and number of pixels.
| abbreviation | Surname | x | y | SAR | DAR | PAR | pixel | Hz | Mpx / s | |
|---|---|---|---|---|---|---|---|---|---|---|
| SQCIF | S emi QCIF | 128 | × | 96 | 4∶3 | 4∶3 | 1∶1 | 12,288 | 30th | 0.4 |
| QCIF | Q uarter CIF | 176 | × | 144 | 11-9 | 4∶3 | 1,091 | 25,344 | 30th | 0.8 |
| CIF | C ommon I ntermediate F ormat | 352 | × | 288 | 11-9 | 4∶3 | 1,091 | 101,376 | 30th | 3 |
| 2CIF | 2 CIF | 704 | × | 288 | 22: 9 | 4∶3 | 0.545 | 202.752 | 30th | 6.1 |
| 4CIF | 2 × 2 CIF | 704 | × | 576 | 11-9 | 4∶3 | 1,091 | 405.504 | 30th | 12.2 |
| 9CIF | 3 × 3 CIF | 1056 | × | 864 | 11-9 | 4∶3 | 1,091 | 912,384 | 30th | 27.4 |
| 16CIF | 4 × 4 CIF | 1408 | × | 1152 | 11-9 | 4∶3 | 1,091 | 1,622,016 | 30th | 48.7 |
| QSIF (NTSC) | Q uarter SIF NTSC | 176 | × | 120 | 22-15 | 4∶3 | 0.909 | 21,120 | 30th | 0.6 |
| QSIF (PAL) | Q uarter SIF PAL | 176 | × | 144 | 11-9 | 4∶3 | 1,091 | 25,344 | 25th | 0.6 |
| SIF (NTSC) | S ource I nput F ormat NTSC | 352 | × | 240 | 22-15 | 4∶3 | 0.909 | 84,480 | 30th | 2.5 |
| SIF (PAL) | S ource I nput F ormat PAL | 352 | × | 288 | 11-9 | 4∶3 | 1,091 | 101,376 | 25th | 2.5 |
| 2SIF (NTSC) | 2 SIF NTSC | 704 | × | 240 | 44:15 | 4∶3 | 0.454 | 168,960 | 30th | 5.1 |
| 2SIF (PAL) | 2 SIF PAL | 704 | × | 288 | 22: 9 | 4∶3 | 0.545 | 202.752 | 25th | 5.1 |
| 4SIF (NTSC) | 2 × 2 SIF NTSC | 704 | × | 480 | 22-15 | 4∶3 | 0.909 | 337.920 | 30th | 10.1 |
| 4SIF (PAL) | 2 × 2 SIF PAL | 704 | × | 576 | 11-9 | 4∶3 | 1,091 | 405.504 | 25th | 10.1 |
| 9SIF (NTSC) | 3 × 3 SIF NTSC | 1056 | × | 720 | 22-15 | 4∶3 | 0.909 | 760.320 | 30th | 22.8 |
| 9SIF (PAL) | 3 × 3 SIF PAL | 1056 | × | 864 | 11-9 | 4∶3 | 1,091 | 912,384 | 25th | 22.8 |
| 16SIF (NTSC) | 4 × 4 SIF NTSC | 1408 | × | 960 | 22-15 | 4∶3 | 0.909 | 1,351,680 | 30th | 40.6 |
| 16SIF (PAL) | 4 × 4 SIF PAL | 1408 | × | 1152 | 11-9 | 4∶3 | 1,091 | 1,622,016 | 25th | 40.6 |
| qD1 (NTSC) | Q uarter D1 NTSC | 360 | × | 240 | 3∶2 | 4∶3 | 0.889 | 86,400 | 30th | 2.6 |
| qD1 (PAL) | Q uarter D1 PAL | 360 | × | 288 | 5∶4 | 4∶3 | 1,066 | 103,680 | 25th | 2.6 |
| cD1 (NTSC) | C ropped D1 NTSC | 704 | × | 480 | 22-15 | 4∶3 | 0.909 | 337.920 | 30th | 10.1 |
| cD1 (PAL) | C ropped D1 PAL | 704 | × | 576 | 11-9 | 4∶3 | 1,091 | 405.504 | 25th | 10.1 |
| D1 (NTSC) | F ull D1 NTSC | 720 | × | 480 | 3∶2 | 4∶3 | 0.889 | 345,600 | 30th | 10.4 |
| D1 (PAL) | F ull D1 PAL | 720 | × | 576 | 5∶4 | 4∶3 | 1,066 | 414.720 | 25th | 10.4 |