Re: [MMUSIC] BUNDLE/SDP : ISSUE#1: Should BUNDLE allow/disallow PT sharing ??

[Harald Alvestrand <[e-mail]>]

0: No, using PT 98 for both audio and video should absolutely not be
allowed. Reuse of a PT for different codecs MUST NOT be done. I thought
that was pretty clear in BUNDLE already; if it's not 100% crystal clear, it
needs to be made clear.

1: Either the SDP should be rejected outright or the response to this SDP
needs to disallow bundling those two lines. This belongs in the BUNDLE
spec, and I thought it was pretty clear already.

2: If the question is about the "a=rtcp-fb" field, I think it should be
classified as NORMAL. If it is about "a=rtcp-fb:98", it makes more sense to
call it IDENTICAL.





On Tue, Oct 22, 2013 at 8:36 AM, Suhas Nandakumar <[e-mail]>wrote:

> Hello All
>
>    Section 5.2 in the draft-nandakumar-mmusic-sdp-mux-attributes-05
> defines one category of OPEN ISSUE that was raised while analyzing
> multiplexing behavior of RFC4855, RFC5583 attributes for example.
>
> As an example, let's consider the  SDP Example (copied from the draft)
>
>
>
> // PTs are shared and have different feedback types
>    a=group:BUNDLE audio video
>    m=audio 3456 RTP/AVP 98
>    a=mid:audio
>    a=rtpmap:98 iLBC/8000
>    a=rtcp-fb ack                  // Positive ACK
>    m=video 3456 RTP/AVP 98
>    a=mid:video
>    a=rtpmap:98 VP8/90000
>    a-rtcp-fb:98 nack rpsi        // Nack ACK
>
>
> In the above case, PT 98 is repeated between the audio and video media
> lines. Audio media line has rtcp-fb ack and video media line has rtcp-fb
> nack.
>
> Since RTCP reporting happens per RTP Session, we can see the following
> high level questions :
>
> 0. Should this be allowed ?
>
> 1. What should be the expected behavior in this scenario ?
>
> 2. What category assignment makes sense in here - IDENTICAL or NORMAL ??
>
>
> Cheers
> Suhas
>
>
>