Draft: draft-ietf-rtcweb-jsep

Commentary: Reference transceiver direction as opposed to " active " senders / receivers We initially thought there would be an " active " bit on senders / receivers to control the direction of a media description , but instead we now have a " setDirection " API on the transceiver . So we should reference that . 
 lgtm
Paragraph (version A):
RtpSenders allow the application to control how RTP media is sent.
In particular, the application can control whether an RtpSender is
active or not, which affects the directionality attribute of the
associated m= section.
Paragraph (version A):
RtpReceivers allows the application to control how RTP media is
received.  In particular, the application can control whether an
RtpReceiver is active or not, which affects the directionality
attribute of the associated m= section.
Paragraph (version B):
RtpSenders allow the application to control how RTP media is sent.
Paragraph (version B):
RtpReceivers allows the application to control how RTP media is
received.
Paragraph (version A):
If the RtpTransceiver's RtpSender is active, and the application
has specified RID values or has specified more than one encoding
in the RtpSenders's parameters, an "a=rid" line for each encoding
specified.  The "a=rid" line is specified in I-D.ietf-mmusic-rid,
and its direction MUST be "send".  If the application has chosen a
RID value, it MUST be used as the rid-identifier; otherwise a RID
value MUST be generated by the implementation.  When generating
RID values, it is RECOMMENDED that the values be 3 bytes or less,
to allow them to efficiently fit into the RTP header extension
defined in I-D.ietf-avtext-rid, Section 11.  If no encodings have
been specified, or only one encoding is specified but without a
RID value, then no "a=rid" lines are generated.
Paragraph (version A):
If the RtpTransceiver's RtpSender is active and more than one
"a=rid" line has been generated, an "a=simulcast" line, with
direction "send", as defined in I-D.ietf-mmusic-sdp-simulcast,
Section 6.2.  The list of RIDs MUST include all of the RID
identifiers used in the "a=rid" lines for this m= section.
Paragraph (version B):
If the RtpTransceiver has a sendrecv or sendonly direction, and
the application has specified RID values or has specified more
than one encoding in the RtpSenders's parameters, an "a=rid" line
for each encoding specified.  The "a=rid" line is specified in I-
D.ietf-mmusic-rid, and its direction MUST be "send".  If the
application has chosen a RID value, it MUST be used as the rid-
identifier; otherwise a RID value MUST be generated by the
implementation.  When generating RID values, it is RECOMMENDED
that the values be 3 bytes or less, to allow them to efficiently
fit into the RTP header extension defined in I-D.ietf-avtext-rid,
Section 11.  If no encodings have been specified, or only one
encoding is specified but without a RID value, then no "a=rid"
lines are generated.
Paragraph (version B):
If the RtpTransceiver has a sendrecv or sendonly direction and
more than one "a=rid" line has been generated, an "a=simulcast"
line, with direction "send", as defined in I-D.ietf-mmusic-sdp-
simulcast, Section 6.2.  The list of RIDs MUST include all of the
RID identifiers used in the "a=rid" lines for this m= section.
Paragraph (version A):
If no RtpTransceiver was found in the previous step, create
one with an inactive RtpSender and active RtpReceiver.
Paragraph (version B):
If no RtpTransceiver was found in the previous step, create
one with a recvonly direction.