2.2 Message Syntax

This extension allows the DVI4 audio codec to be utilized with the H.323 Protocol [H323-1.2]. This extension is implemented according to the H.245 Extension Procedure, as specified in [H245-1.3] Appendix IV.

Microsoft has added support to the H.245 terminal capability negotiation procedure to allow for use of the Digital Video Interactive 4 (DVI4) audio codec at the 16-kHz sample rate.

Support for the 16-kHz DVI4 codec MUST be indicated via the following steps:

  1. The Abstract Syntax Notation One (ASN.1) AudioCapability message included in the H.245 negotiation procedure MUST contain a nonStandardData of type nonStandardParameter Sequence as described in Annex A of [H245-1.3].

  2. The nonStandardParameter MUST be set to include the following items:

    • The OBJECT IDENTIFIER (nonStandardIdentifier) MUST be set using the following ANS.1 value.

       { 1 3 6 1 4 1 311 19 2 }
      
    • The OCTET STRING (data) portion MUST be set to the following value.

       11 00 01 00 80 3E 00 00 40 1F 00 00 01 00 04 00 02 00 14 00