N.2 Examples
26.1143GPPIP Multimedia Subsystem (IMS)Media handling and interactionMultimedia telephonyRelease 18TS
Table N.x shows example values of b=AS in IPv4 and IPv6 for each source bit-rate and image size pair of H.264/AVC. These values are determined from encoding a variety of content with the codec targeting a particular source bit-rate and then measuring the fluctuations of the encoded bit-rate in order to determine the recommended b=AS values. As the source bit-rate increases, the relative differences of b=AS values in IPv4 and IPv6 decrease as the proportion of RTP/UDP/IP headers in the packet decreases, but the required margin for the fluctuations increases. Different source bit-rates and b=AS values can be used for the same image size depending on service policy, alternative codec configurations, and the amount of bit-rate variation introduced by the rate control algorithm implementation.
Table N.1: Example of b=AS values for H.264/AVC
|
Image size |
Source bit-rate |
b=AS (IPv4) |
b=AS (IPv6) |
Notes |
|
176×144 |
48 |
64 |
66 |
Maximum SDU size=1400 octets, average packet rate=14 packets/s, picture rate=7 pictures/s, average packets per picture=2 packets/picture, average header (RTP/UDP/IP) bit-rate=5/7 kbps (IPv4/IPv6) |
|
320×240 |
300 |
384 |
399 |
Maximum SDU size=1400 octets, average packet rate=60 packets/s, picture rate=15 pictures/s, average packets per picture=4 packets/picture, average header (RTP/UDP/IP) bit-rate=20/32 kbps (IPv4/IPv6) |
|
640×480 |
512 |
639 |
653 |
Maximum SDU size=1400 octets, average packet rate=60 packets/s, picture rate=15 pictures/s, average packets per picture=4 packets/picture, average header (RTP/UDP/IP) bit-rate=20/32 kbps (IPv4/IPv6) |
Annex O (informative):
IANA registration information for RTP Header Extensions