Re: [MMUSIC] RTSP 2.0 SDP issue: Directionality attribute

[Magnus Westerlund <[e-mail]>]

Thanks,

Change applied to source.

Cheers

Magnus

On 2013-03-15 08:25, Sean Sheedy wrote:
> This change sounds good to me.  I would recommend changing "In SDP
> provided ..." to "SDP provided ...".
> 
> Sean
> 
> 
> On 03/14/2013 07:12 PM, Magnus Westerlund wrote:
>> WG,
>>
>> Flemming has found an issue in Section D.1.5. This is that this section
>> actually redefined the default behavior of the a=sendrecv, a=recvonly,
>> a=sendonly. This is clearly unsuitable and I propose that we change the
>> current text:
>>
>> D.1.5.  Directionality of media stream
>>
>>     The SDP attributes "a=sendrecv", "a=recvonly" and "a=sendonly"
>>     provide instructions about the direction the media streams flow
>>     within a session.  When using RTSP the SDP can be delivered to a
>>     client using either RTSP DESCRIBE or a number of RTSP external
>>     methods, like HTTP, FTP, and email.  Based on this the SDP applies to
>>     how the RTSP client will see the complete session.  Thus media
>>     streams delivered from the RTSP server to the client, would be given
>>     the "a=recvonly" attribute.
>>
>>     The direction attributes are not commonly used in SDPs for RTSP, but
>>     may occur. "a=recvonly" in a SDP provided to the RTSP client MUST
>>     indicate that media delivery will only occur in the direction from
>>     the RTSP server to the client.  In SDP provided to the RTSP client
>>     that lacks any of the directionality attributes (a=recvonly,
>>     a=sendonly, a=sendrecv) MUST behave as if the "a=recvonly" attribute
>>     was received.  Note that this overrules the normal default rule
>>     defined in SDP[RFC4566].  The usage of "a=sendonly" or "a=sendrecv"
>>     is not defined, nor is the interpretation of SDP by other entities
>>     than the RTSP client.
>>
>> To instead become:
>>
>> D.1.5.  Directionality of media stream
>>
>>     The SDP attributes "a=sendrecv", "a=recvonly" and "a=sendonly"
>>     provide instructions about the direction the media streams flow
>>     within a session.  When using RTSP the SDP can be delivered to a
>>     client using either RTSP DESCRIBE or a number of RTSP external
>>     methods, like HTTP, FTP, and email.  Based on this the SDP applies to
>>     how the RTSP client will see the complete session.  Thus media
>>     streams delivered from the RTSP server to the client, would be given
>>     the "a=recvonly" attribute.
>>
>>     "a=recvonly" in a SDP provided to the RTSP client indicates that
>>     media delivery will only occur in the direction from the RTSP server
>>     to the client.  In SDP provided to the RTSP client that lacks any of
>>     the directionality attributes (a=recvonly, a=sendonly, a=sendrecv)
>>     would be interpreated as having a=sendrecv.  At the time of writing
>>     there exist no RTSP mode suitable for media traffic in the direction
>>     from the RTSP client to the server.  Thus all RTSP SDP SHOULD have
>>     a=recvonly attribute when using the PLAY mode defined in this
>>     document.  If future modes are defined for media in client to server
>>     direction, then usage of a=sendonly, or a=sendrecv may become
>>     suitable to indicate intended media directions.  The usage of
>>     "a=sendonly" or "a=sendrecv" SHOULD then be well defined.
>>
>> This means that we expect SDP files for RTSP 2.0 to do contain the
>> directionality attribute.
>>
>> Please provide feedback on this proposal.
>>
>> Cheers
>>
>> Magnus Westerlund
>>
>> ----------------------------------------------------------------------
>> Multimedia Technologies, Ericsson Research EAB/TVM
>> ----------------------------------------------------------------------
>> Ericsson AB                | Phone  [phone]
>> Färögatan 6                | Mobile [phone]
>> SE-164 80 Stockholm, Sweden| mailto: [e-mail]
>> ----------------------------------------------------------------------
>>
>> _______________________________________________
>> mmusic mailing list
>> [e-mail]
>> https://www.ietf.org/mailman/listinfo/mmusic
> 
> 


-- 

Magnus Westerlund

----------------------------------------------------------------------
Multimedia Technologies, Ericsson Research EAB/TVM
----------------------------------------------------------------------
Ericsson AB                | Phone  [phone]
Färögatan 6                | Mobile [phone]
SE-164 80 Stockholm, Sweden| mailto: [e-mail]
----------------------------------------------------------------------