Please review the following media type registration. The source document is http://www.ietf.org/internet-drafts/draft-ietf-avt-rtp-atrac-family-13.txt, which is currently undergoing Working Group Last Call in the AVT Working Group. Tom Taylor AVT co-Chair The media subtype for the Adaptive TRansform Codec version X (ATRAC-X) uses the template defined in RFC 4855 [6]. Note, any unknown parameter MUST be ignored by the receiver. Type name: audio Subtype name: atrac-x Required parameters: rate: Represents the sampling frequency in Hz of the original audio data. Permissible values are 44100 and 48000. baseLayer: Indicates the encoded bit-rate in kbps for the audio data to be streamed. Permissible values are 32, 48, 64, 96, 128, 160, 192, 256, 320 and 352. channelID: Indicates the number of channels and channel layout according to the table1 in Section 7.4. Note that this layout is different from that proposed in RFC 3551 [3]. However, as channelID = 0 defines an ambiguous channel layout, the channel mapping defined in Section 4.1 of [3] could be used. Permissible values are 0, 1, 2, 3, 4, 5, 6, 7. Optional parameters: ptime: see RFC4566[2] maxptime: see RFC4566[2] The value of the parameter MUST be a multiple of 46.4(ms) when rate parameter is 44100, and 42.6(ms) when rate parameter is 48000. If this parameter is not present, the sender MAY encapsulate a maximum of 16 encoded frames into one RTP packet, in streaming of ATRAC-X. maxRedundantFrames: The maximum number of redundant frames that may be sent during a session in any given packet under the redundant framing mechanism detailed in the draft. Allowed values are integers in the range 0 to 15, inclusive. If this parameter is not used, a default of 15 MUST be assumed. delayMode: Indicates a desire to use low-delay features, in which case the decoder will process received data accordingly based on this value. Permissible values are 2 and 4. Encoding considerations: This media type is framed and contains binary data. Security considerations: See Section 9 of this document. Interoperability considerations: none Published specification: none Applications that use this media type: Audio and video streaming and conferencing tools. Additional information: none Magic number(s): none File extension(s): 'atx', 'aa3', and 'omg' Macintosh file type code(s): none Person & email address to contact for further information: Mitsuyuki Hatanaka actech@jp.sony.com Intended usage: COMMON Restrictions on usage: This media type depends on RTP framing, and hence is only defined for transfer via RTP. Author/Change controller: Mitsuyuki Hatanaka actech@jp.sony.com