Review requested: audio/atrac3 media type registration

[actech]

Hi Mark,

In ATRAC receiver side, it is required to know sampling frequency, bit-rate and
channel configuration in order to switch and initialize the decoder and
associated hardware for immediate starting of ATRAC3, ATRAC-X or ATRAC Advanced
Lossless decoding.

We think it is the best way to signal above parameters in SDP session with
media type registarion procedure.

Best Regards,

Jun



> On 2/19/08, Tom Taylor <tom.taylor at rogers.com> wrote:
>> 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 3 (ATRAC3)
>>     uses the template defined in RFC 4855 [6].
>>
>>     Note, any unknown parameter MUST be ignored by the receiver.
>>
>>     Type name:  audio
>>
>>     Subtype name:  atrac3
>>
>>     Required parameters:
>>     rate:  Represents the sampling frequency in Hz of the original
>>     audio data.  Permissible value is 44100 only.
> 
> Why is this required, yet has just the one permissible value?
> 
>>     baseLayer:  Indicates the encoded bit-rate in kbps for the audio
>>     data to be streamed.  Permissible values are 66, 105 and 132.
> 
> Can this - or the rate even - not be determined from the data itself?
> I'm just asking, as I know nothing about audio formats.
> 
> Everything else looks fine AFAICT.
> 
> Mark.