(RFC 4352 published January 2006, subtype last updated January 2006)

Media Type name:     audio

Media subtype name:  AMR-WB+

Required parameters:

None

Optional parameters:

channels:       The maximum number of audio channels used by the
			   audio frames.  Permissible values are 1 (mono) or 2
			   (stereo).  If no parameter is present, the maximum
			   number of channels is 2 (stereo).  Note: When set to
			   1, implicitly the stereo frame types cannot be used.

interleaving:   Indicates that interleaved mode SHALL
			   be used for the payload.  The parameter specifies
			   the number of transport frame slots required in a
			   deinterleaving buffer (including the frame that is
			   ready to be consumed).  Its value is equal to one
			   plus the maximum number of frames that precede any
			   frame in transmission order and follow the frame in
			   RTP timestamp order.  The value MUST be greater than
			   zero.  If this parameter is not present,
			   interleaved mode SHALL NOT be used.

int-delay:      The minimal media time delay in RTP timestamp ticks
			   that is needed in the deinterleaving buffer, i.e.,
			   the difference in RTP timestamp ticks between the
			   earliest and latest audio frame present in the
			   deinterleaving buffer.

ptime:          See Section 6 in RFC 2327 [6].

maxptime:       See Section 8 in RFC 3267 [7].

Restriction on Usage:
			This type is only defined for transfer via RTP (STD 64).

Encoding considerations:
			An RTP payload according to this format is binary data
			and thus may need to be appropriately encoded in non-
			binary environments.  However, as long as used within
			RTP, no encoding is necessary.

Security considerations:
			See Section 6 of RFC 4352.

Interoperability considerations:
			To maintain interoperability with AMR-WB-capable end-
			points, in cases where negotiation is possible and the
			AMR-WB+ end-point supporting this format also supports
			RFC 3267 for AMR-WB transport, an AMR-WB+ end-point
			SHOULD declare itself also as AMR-WB capable (i.e.,
			supporting also "audio/AMR-WB" as specified in RFC
			3267).

			As the AMR-WB+ decoder is capable of performing stereo
			to mono conversions, all receivers of AMR-WB+ should be
			able to receive both stereo and mono, although the
			receiver is only capable of playout of mono signals.

Public specification:
			RFC 4352
			3GPP TS 26.290, see reference [1] of RFC 4352

Additional information:
			This MIME type is not applicable for file storage.
			Instead, file storage of AMR-WB+ encoded audio is
			specified within the 3GPP-defined ISO-based multimedia
			file format defined in 3GPP TS 26.244; see reference
			[14] of RFC 4352.  This file format has the MIME types
			"audio/3GPP" or "video/3GPP" as defined by RFC 3839
			[15].

Person & email address to contact for further information:
			magnus.westerlund&ericsson.com
			ari.lakaniemi&nokia.com

Intended usage: COMMON.
			It is expected that many IP-based streaming
			applications will use this type.

Change controller:
			IETF Audio/Video Transport working group delegated from
			the IESG.