From: "Yong Xin" <[EMAIL PROTECTED]>
We have different interpretation regarding to the "c=" line definition in
RFC 2327.
Session description
c=* (connection information - not required if included in all media)
Media description
c=* (connection information - optional if included at session-level)
I think "c=" line is optional when SDP has no "m=" line, since I don't see a
use case to present connection info when there's no media
description.
Having no media descriptions in SDP is perverse, but RFC 2327 clearly
allows it (Appendix A):
announcement = proto-version
origin-field
session-name-field
information-field
uri-field
email-fields
phone-fields
connection-field
bandwidth-fields
time-fields
key-field
attribute-fields
media-descriptions
media-descriptions = *( media-field
information-field
*(connection-field)
bandwidth-fields
key-field
attribute-fields )
Within that context, your interpretation is clearly correct -- when a
statement says that "X is true for all Y", and if no Y's exist, then
the statement makes no constraint at all, as there are no Y's for it
to apply to.
Dale
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