Review requested: audio/atrac-advanced-lossless media type registration

[Tom Taylor]

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 Lossless version
    (ATRAC Advanced Lossless) uses the template defined in RFC 4855 [6].

    Note, any unknown parameter MUST be ignored by the receiver.

    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.

    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 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.  Permissible values are 0, 1, 2,
    3, 4, 5, 6, 7.

    ptime:    see RFC4566[2]

    maxptime: see RFC4566[2]
    In streaming of ATRAC Advanced Lossless, a multiple frames can
    not 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 reciever side.
    The value of the parameter MUST be 11.5, 23.2 or 46.4(ms).

    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): 'aal', 'aa3', and 'omg'
    Macintosh file type code(s): none

    Person & email address to contact for further information:

    Mitsuyuki Hatanaka
    actech at 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 at jp.sony.com