(RFC 5188 published February 2008, subtype last updated February 2008) Type name: audio Subtype name: EVRCWB1 Required parameters: None Optional parameters: These parameters apply to RTP transfer only. mode-set-recv: A subset of EVRC-WB modes. Possible values are a comma-separated list of modes from the set {0,4,7} (see Table 2.5.1.2-1 in 3GPP2 C.S0014-C). A decoder can use this attribute to inform an encoder of its preference to operate in a specified subset of modes. A value of 0 signals the support for wideband fixed rate (full or half rate, depending on the value of the 'fixedrate' parameter). A value of 4 signals narrowband fixed full rate. A value of 7 signals narrowband fixed half rate. Absence of this parameter signals mode 0. sendmode: A mode of the EVRC-WB codec. An encoder can use this to signal its current mode of operation. Possible values are 0,4,7 (see Table 2.5.1.2-1 in 3GPP2 C.S0014-C). 'sendmode' with value 0 signals wideband fixed-rate operation (full or half rate, depending on the value of the 'fixedrate' parameter). 'sendmode' with value 4 signals narrowband fixed full-rate operation. 'sendmode' with value 7 signals narrowband fixed half-rate operation. The 'fixedrate' parameter MUST NOT be present when the 'sendmode' value is 4 or 7. Absence of this parameter signals mode 0. ptime: See RFC 8866. maxptime: See RFC 8866. fixedrate: Indicates the EVRC-WB rate of the session while in single- rate operation. Valid values include 0.5 and 1, where a value of 0.5 indicates the 1/2 rate while a value of 1 indicates the full rate. If this parameter is not present, 1/2 rate is assumed. silencesupp: See Section 6.1 in RFC 4788. dtxmax: See Section 6.1 in RFC 4788. dtxmin: See Section 6.1 in RFC 4788. hangover: See Section 6.1 in RFC 4788. Encoding considerations: This media type is framed binary data (see RFC 4288, Section 4.8) and is defined for transfer of EVRC-WB encoded data via RTP using the compact bundle packet format specified in RFC 4788. Security considerations: See Section 18 of RFC 5188. Interoperability considerations: None Published specification: The EVRC-WB vocoder is specified in 3GPP2 C.S0014-C. The transfer method with the compact bundled packet format via RTP is specified in RFC 4788 and RFC 5188. 3GPP2 C.S0050-B, 3GPP2 File Formats for Multimedia Services. 3GPP2 specifications are publicly accessible at http://www.3gpp2.org Applications that use this media type: It is expected that many VoIP applications (as well as mobile applications) will use this type. Additional information: None Person & email address to contact for further information: Harikishan Desineni Intended usage: COMMON Restrictions on usage: This media type depends on RTP framing and hence is only defined for transfer via RTP [6]; the RTP payload format specified in Section 4 of RFC 4788 SHALL be used. This media type SHALL NOT be used for storage or file transfer using the file format defined in Section 8 of RFC 5188; instead, audio/EVRCWB SHALL be used. Author: Harikishan Desineni Change controller: IETF Audio/Video Transport working group delegated from the IESG.