Compaq ProLiant 1600 Video Streaming Technology - Page 9

H.261 Resolutions, H.263 Resolutions

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ECG068/0798 WHITE PAPER (cont.) 9... Video Codec Standards H.261 The H.261 video-only codec standard was created by the ITU in 1990 for global video phone and video conferencing applications over ISDN. It was designed for low bit rates assuming limited motion as is typical with videophone applications. It was also assumed that ISDN would be deployed worldwide. Since each ISDN B Channel has a data rate of 64 Kbps, H.261 is also sometimes referred to as "Px64" where P can take integer values from 1 to 30. For compatibility between different TV systems-NTSC, PAL, SECAM-a Common Intermediate Format (CIF) was defined that will work across displays for all of these systems. CIF and Quarter-CIF resolution are defined as: H.261 Resolutions Format Resolution QCIF: 176 x 144 CIF: 352 x 288 H.261 frame rates can be 7.5, 10, 15, or 30 fps. H.261 has been the most widely implemented video conferencing standard in North America, Europe, and Japan, and formed the starting point for the development of the MPEG-1 standard described below. H.263 H.263 was developed by the ITU in 1994 as an enhancement to H.261 for even lower bit rate applications. It is intended to support videophone applications using the newer generation of PSTN modems at 28.8 Kbps and above. It benefits from the experience gained on the MPEG-1 standard. It supports five picture formats: H.263 Resolutions Format Resolution Sub-QCIF: 128 x 96 QCIF: 176 x 144 CIF: 352 x 288 4CIF: 704 x 576 16CIF 1408 x 1152 Bitrates range from 8 Kbps to 1.5 Mbps. H.263 is the starting basis for MPEG-4 discussed below. JPEG and MJPEG JPEG stands for "Joint Photographic Experts Group." This group developed a compression standard for 24-bit "true-color" photographic images. JPEG works by first converting the image from an RGB format to a YCrCb format described above to reduce the file size to 1/3 or 1/2 of its original size. It then applies a sophisticated algorithm to 8x8 blocks of pixels to round off and quantize changes in luminance and color based on the properties of the human eye that detects subtle changes in luminance more than in color. This lossy compression technique has compression ratios in the range of 2-30.

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W
HITE
P
APER
(cont.)
9
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Video Codec Standards
H.261
The H.261 video-only codec standard was created by the ITU in 1990 for global video phone and
video conferencing applications over ISDN.
It was designed for low bit rates assuming limited
motion as is typical with videophone applications.
It was also assumed that ISDN would be
deployed worldwide.
Since each ISDN B Channel has a data rate of 64 Kbps, H.261 is also
sometimes referred to as "Px64" where P can take integer values from 1 to 30.
For compatibility
between different TV systems—NTSC, PAL, SECAM—a Common Intermediate Format (CIF)
was defined that will work across displays for all of these systems.
CIF and Quarter-CIF
resolution are defined as:
H.261 Resolutions
Format
Resolution
QCIF:
176 x 144
CIF:
352 x 288
H.261 frame rates can be 7.5, 10, 15, or 30 fps.
H.261 has been the most widely implemented video conferencing standard in North America,
Europe, and Japan, and formed the starting point for the development of the MPEG-1 standard
described below.
H.263
H.263 was developed by the ITU in 1994 as an enhancement to H.261 for even lower bit rate
applications.
It is intended to support videophone applications using the newer generation of
PSTN modems at 28.8 Kbps and above.
It benefits from the experience gained on the MPEG-1
standard.
It supports five picture formats:
H.263 Resolutions
Format
Resolution
Sub-QCIF:
128 x 96
QCIF:
176 x 144
CIF:
352 x 288
4CIF:
704 x 576
16CIF
1408 x 1152
Bitrates range from 8 Kbps to 1.5 Mbps.
H.263 is the starting basis for MPEG-4 discussed below.
JPEG and MJPEG
JPEG stands for "Joint Photographic Experts Group."
This group developed a compression
standard for 24-bit "true-color" photographic images.
JPEG works by first converting the image
from an RGB format to a YCrCb format described above to reduce the file size to 1/3 or 1/2 of its
original size.
It then applies a sophisticated algorithm to 8x8 blocks of pixels to round off and
quantize changes in luminance and color based on the properties of the human eye that detects
subtle changes in luminance more than in color.
This lossy compression technique has
compression ratios in the range of 2-30.