RTP
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... EVRC and EVRC-B-encoded speech
transported via RTP. Voice over IP (VoIP) applications operating
...
... wireless networks require such EVRC
RTP payload capabilities for efficient use of the bandwidth.
...
... EVRC-B and EVRC codecs do not interoperate with each
other. At the initiation of an RTP session, the RTP sender and
receiver ...
... EVRC codecs do not interoperate with each
other. At the initiation of an RTP session, the RTP sender and
receiver need to indicate (e.g., using MIME subtypes ...
... 3558prop
allows bundling of multiple speech frames of different rates in a
single RTP packet, sending mode change requests, and interleaving.
To support these functions, a Table of Contents (ToC ...
... Table of Contents (ToC) is used in each
RTP packet, in addition to the standard RTP header. The size of the
ToC ...
... ToC) is used in each
RTP packet, in addition to the standard RTP header. The size of the
ToC varies depending on the number of EVRC ...
... wireless links. It eliminates the
need for a ToC by requiring that each RTP packet contain only one
speech frame (of any allowable rate), i.e., bundling is not allowed.
Moreover, interleaving and mode change requests are not supported in
...
...
A packet in the compact bundled format consists of an RTP header,
followed by a sequence of one or more consecutive EVRC/EVRC-B codec ...
... 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RTP Header [4] |
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
...
... If this parameter is not present, the default value 1 MUST be
assumed. If the RTP receiver indicates through the use of SIP
signaling ...
... update interval in number of frames. During DTX,
the RTP sender occasionally updates the RTP receiver about the
change in background noise characteristics, etc., by sending a
...
... DTX,
the RTP sender occasionally updates the RTP receiver about the
change in background noise characteristics, etc., by sending a
new silence frame to the RTP receiver ...
... RTP receiver about the
change in background noise characteristics, etc., by sending a
new silence frame to the RTP receiver. The RTP receiver may
use 'dtxmax' to indicate to the RTP sender ...
... change in background noise characteristics, etc., by sending a
new silence frame to the RTP receiver. The RTP receiver may
use 'dtxmax' to indicate to the RTP sender the maximum interval
...
... RTP receiver. The RTP receiver may
use 'dtxmax' to indicate to the RTP sender the maximum interval
(in number of frames) between any two DTX updates it expects to
...
... (in number of frames) between any two DTX updates it expects to
receive from the RTP sender.
If this parameter is not present in a session ...
... session.
Note also that if the RTP receiver elects to detect DTX using
dtxmax, the dtxmax parameter will affect the amount of delay
...
... DTX using
dtxmax, the dtxmax parameter will affect the amount of delay
the RTP receiver sees before detecting DTX in the stream.
...
... minimum DTX update interval in number of frames. The RTP
receiver may use 'dtxmin' to indicate to the RTP sender the
minimal interval (in number of frames) between any two DTX ...
... DTX update interval in number of frames. The RTP
receiver may use 'dtxmin' to indicate to the RTP sender the
minimal interval (in number of frames) between any two DTX
...
... minimal interval (in number of frames) between any two DTX
updates it expects to receive from the RTP sender.
If this parameter is not present, the default value ...
... setting up an RTP session that uses DTX, an RTP receiver
can use this parameter to signal the number of silence frames
it expects to receive before the beginning of DTX ...
... to 1 or greater since the presence of silence frames at the end
of an active speech can help the RTP receiver to identify the
beginning of the DTX period.
...
... 4288, Section 4.8)
and is defined for transfer of EVRC-encoded data via RTP, using
the compact bundled format as described in RFC 4788prop.
...
... Restrictions on usage:
This media type depends on RTP framing; hence, it is only defined
for transfer via RTP (RFC 3550std64 ...
... media type depends on RTP framing; hence, it is only defined
for transfer via RTP (RFC 3550std64 [5]). Transfer within other
...
... 4288, Section 4.8)
and is defined for transfer of EVRC-B-encoded data via RTP using
the Interleaved/Bundled packet format ...
... Restrictions on usage:
This media type may be used with RTP framing (RFC 3550std64 [5]) and as
...
... 5]) and as
a storage format. When used with RTP, the procedures in Section 3
MUST be followed. In all other contexts, the storage format ...
... 4288, Section 4.8)
and is defined for transfer of EVRC-B-encoded data via RTP using
the Header-Free packet format specified in RFC 3558prop ...
... Restrictions on usage:
This media type depends on RTP framing; hence, it is only defined
for transfer via RTP (RFC 3550std64 ...
... media type depends on RTP framing; hence, it is only defined
for transfer via RTP (RFC 3550std64 [5]). Transfer within other
...
... 4288, Section 4.8)
and is defined for transfer of EVRC-B-encoded data via RTP using
the compact bundled format as described in RFC 4788prop.
...
... Restrictions on usage:
This media type depends on RTP framing; hence, it is only defined
for transfer via RTP (RFC 3550std64 ...
... media type depends on RTP framing; hence, it is only defined
for transfer via RTP (RFC 3550std64 [5]). Transfer within other
...
... 4288, Section 4.8),
and is defined for transfer of EVRC-encoded data via RTP using the
Interleaved/Bundled packet format ...
... Restrictions on usage:
This media type may be used with RTP framing (RFC 3550std64 [5]) and as
...
... 5]) and as
a storage format. When used with RTP, the procedures in RFC 3558prop,
Section 4.1, MUST be followed. In all other contexts ...
... 4288, Section 4.8)
and is only defined for transfer of EVRC-encoded data via RTP
using the Header-Free packet format specified in Section 4.2 of
...
... Restrictions on usage:
This media type depends on RTP framing; hence, it is only defined
for transfer via RTP (RFC 3550std64 ...
... media type depends on RTP framing; hence, it is only defined
for transfer via RTP (RFC 3550std64 [5]). Transfer within other
...
... SDP)
[7], which is commonly used to describe RTP sessions. When SDP is
used to specify sessions ...
...
m=audio 49120 RTP/AVP 97
a=rtpmap:97 EVRC1/8000
a=fmtp:97 fixedrate=0.5
...
...
m=audio 49120 RTP/AVP 97
a=rtpmap:97 EVRCB1/8000
a=fmtp:97 fixedrate=0.5
...
... reasonable values are expected to be supported. In particular, when
DTX is supported, the RTP sender implementation SHOULD support
hangover, dtxmin, and dtxmax values from 0 to 255. Thus, the
standard usage of Offer/Answer ...
... default. Moreover, if the indicated value of dtxmin is larger
than that of dtxmax, an RTP sender MUST ignore the indicated
values and MUST fall back on using the default dtxmin and dtxmax
values.
...
... Li, A., "RTP Payload Format for Enhanced Variable Rate Codecs (EVRC) and Selectable Mode Vocoders (SMV)", RFC 3558prop ...
... Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson, "RTP: A Transport Protocol for Real-Time Applications", RFC 3550std64 ...
... Schulzrinne, H. and S. Casner, "RTP Profile for Audio and Video Conferences with Minimal Control", RFC 3551std65, July 2003. ...