(RFC 5584 published July 2009, subtype last updated July 2009) Type name: audio Subtype name: ATRAC-ADVANCED-LOSSLESS Required parameters: rate: Represents the sampling frequency in Hz of the original audio data. Permissible value is 44100 only for High-Speed Transfer mode. Any value of 24000, 32000, 44100, 48000, 64000, 88200, 96000, 176400, and 192000 can be used for Standard mode. baseLayer: Indicates the encoded bit-rate in kbps for the base layer in High-Speed Transfer mode lossless encodings. For Standard lossless mode, this value MUST be 0. The Permissible values for ATRAC3 baselayer are 66, 105, and 132. For ATRAC-X baselayer, they are 32, 48, 64, 96, 128, 160, 192, 256, 320, and 352. blockLength: Indicates the block length. In High-Speed Transfer mode, the value of 1024 and 2048 is used for ATRAC3 based and ATRAC-X based ATRAC Advanced Lossless streaming, respectively. Any value of 512, 1024, and 2048 can be used for Standard mode. 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 in this case. Permissible values are 0, 1, 2, 3, 4, 5, 6, 7. ptime: See RFC 8866. maxptime: See RFC 8866. In streaming of ATRAC Advanced Lossless, multiple frames cannot be transmitted in a single RTP packet, as the frame size is large. So it SHOULD be regarded as the time of one encoded frame in both of the sender and the receiver side. The frame length of ATRAC Advanced Lossless is 512/44100 = 11.6...(ms), 1024/44100 = 23.22...(ms), or 2048/44100 = 46.44...(ms), but fractional value may not be applicable for the SDP definition. So the value of the parameter MUST be 12(ms), 24(ms), or 47(ms) considering safe transmission. Encoding considerations: This media type is framed and contains binary data. Security considerations: This media type does not carry active content. See Section 9 of this document. Interoperability considerations: none Published specification: ATRAC Advanced Lossless Standard Specification [11] Applications that use this media type: Audio and video streaming and conferencing tools. Additional information: none Magic number(s): none File extension(s): 'aal', 'aa3', and 'omg' Macintosh file type code(s): none Person and email address to contact for further information: Mitsuyuki Hatanaka Jun Matsumoto 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: Mitsuyuki Hatanaka Jun Matsumoto actech&jp.sony.com Change controller: IETF AVT WG delegated from the IESG