H.245 for videoFastUpdateMB, videoFastUpdateGOB, videoNotDecodedM Bs (Was Q15: Date: Sat, 12 Feb 2000 19:24:45 -0800)

[Gary Sullivan]

Chris,

Each H.320 frame (ignoring optional encryption) is 640 bits (for clear
channel) of which 16 bits are dedicated to FAS (Frame Alignment Signal) and
BAS (Bit-rate Allocation Signal). 16 / 640 * 100 = 2.5 % overhead. See
ITU-T H.221.

Since H.323 overhead is based on payload size (which varies with codec
output and network characteristics), more parameters are needed to
calculate the overhead. See ITU-T H.225. A good, general source is
"Videoconferencing and Videotelephony," Richard Shaphorst, Artech House,
Inc., (c) 1996.

Barry

At 09:25 AM 2/11/00 -0500, you wrote:
>Hi all
>
>Would someone know the % of overhead in H.323 & H.320
>
>Thanks for any help you can provide
>
>Chris
>Christopher Iles
>Senior
>Technologist
>COMMUNICATIONS RESEARCH CENTER
>e-mail:
>christopher.iles at crc.ca
>3701 Carling Ave
>Tel office: 613 998
>2734
>Ottawa, Ont.   K2H 8S2
>Ops Room : 613 998
>2374                                                           ATTN: BLDG 46