Re: [rtcweb] On the meaning of b=

+Suhas as FYI

Thanks. That's pretty clear.

On Thu, Nov 13, 2014 at 8:49 AM, Randell Jesup <randell-ietf@jesup.org>
wrote:

> On 11/13/2014 12:20 AM, Justin Uberti wrote:
>
>> Following up on the JSEP discussion on b= from Monday:
>>
>> Does anyone know whether b= in an offer represents the value the offerer
>> wants to send, or receive? http://tools.ietf.org/html/
>> draft-ietf-mmusic-sdp-mux-attributes-04#section-6.3 seems to indicate
>> it's a send declaration, but I was previously under the impression that it
>> represents the amount to be received. RFC 4566 is ambiguous on the matter [
>> http://tools.ietf.org/html/rfc4566#section-5.8].
>>
>
> SDP is a description, but really we want to look at Offer-Answer.
>
> In rfc 3264 section 6.1:
>
>    The answerer MAY include a bandwidth attribute for any media stream;
>    this indicates the bandwidth that the answerer would like the offerer
>    to use when sending media.  The value of zero is allowed, interpreted
>    as described in Section 5.
>
>
> and section 7:
>
>    The offerer SHOULD send media according to the value of any ptime and
>    bandwidth attribute in the answer.
>
>
> So, barring explicit instruction elsewhere for a b= type, those are
> receiver preferences.  This matches something I found out many years ago
> (likely in AVT archives somewhere) after I had presumed they were "amount I
> plan to send" (since I had a config for that, I hooked it up to b= as it
> wasn't clear in the SDP spec alone).  Later when I actually started caring
> about b= (TIAS, etc), I found the error.
>
> --
> Randell Jesup -- rjesup a t mozilla d o t com
>
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