Information Technology Reference
In-Depth Information
H.225 performs registration, admission, and status (RAS) signaling for H.323 sessions.
RTP is the transport layer protocol used to transport VoIP packets. RTCP is also a trans-
port layer protocol.
H.323 includes a series of protocols for multimedia, as shown in Table 14-9.
Ta b l e 1 4 - 9
H.323 Protocols
Video
Audio
Data
Transport
H.323 protocol
H.261
H.263
H.264
G.711
G.722
G.723.1
G.728
G.729
T.1 2 2
T.1 2 4
T.1 2 5
T.1 2 6
T.1 2 7
RTP
H.225
H.235
H.245
H.450.1
H.450.2
H.450.3
X.224.0
H.264
H.264 is an ITU-T standard that defines video compression algorithm. It is identical to
ISO/IEC MPEG-4 Part 10 and also called Advanced Video Coding (AVC). It is an upgrade
from the H.263 standard that is found in Flash, YouTube, and Google video today. H.264
also handles encoding of pixel blocks more effectively, thus reducing the pixilation seen
on video conferences when motion occurs. H.264 encodes and transmits two interlaced
fields for each frame: 30 frames per second and 60 fields per second. H.263 only does 30
fields per second.
Ta ble 1 4 -1 0 provides typical bandwidth requirements of H.264 video sources.
Ta b l e 1 4 -1 0
H.264 Video Bandwidth
Video Source
Resolution
Typical Load
Te l e P r e s e n c e 3 0 0 0
1080p
12.3 Mbps
Te l e P r e s e n c e 3 0 0 0
720p
6.75
Te l e P r e s e n c e 1 0 0 0
1080p
4.1 Mbps
Te l e P r e s e n c e 1 0 0 0
720p
2.25 Mbps
Cisco 4500 Video Surveillance
1080p
4-6 Mbps
Cisco DMS - Digital Sign SD
720x480
1.5-2.5 Mbps
Cisco DMS - Digital Sign HD
1080p
8-12 Mbps
Cisco Video Advantage
CIF
768 kbps
Yo u Tu b e H D
720p
2 Mbps
