Final Revision of Changes for H.225.0v4 and H.323v4

Hidenobu Harasaki harasaki at CCM.CL.NEC.CO.JP
Tue Jan 16 05:49:10 EST 2001


Dear Experts,

> Please give me any comments by the end of the business day Tuesday.

I found possible bugs in H.245 Generic Parameter when I was checking
EVRC RTP payload format defined in H.225.0 version 4.
I started checking because a complete different RTP payload format
was proposed and discussed in the last IETF AVT WG meeting.

I believe that each H.245 Generic Parameter should clearly be identified as
collapsing or non-collapsing because ASN.1 syntax treats differerently.
But, Annex F (Logical Channel Bit Rate Management),
Annex J (TDMA ACELP), K (TDMA US1), L (CDMA EVRC) and Example of
H.261 do not have any description on collapsing or non-collapsing.

The bug may cause an interoperability problem between different
implementations because transmitter side can encode a parameter as
either collapsing or non-collapsing, and there is no explicit
decoding rule for receiver side.

Has anyone there implemented TDMA or CDMA codec into H.323?

Best regards,

Hideh

Hidenobu Harasaki           harasaki at bq.jp.nec.com (harasaki at ccm.cl.nec.co.jp)
Senior Manager              Computer & Communication Media Research
                            NEC Corporation
                            Phone: +81 44 856 8083    Fax: +81 44 856 2232

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