AVTEXT Working Group J. Xia
INTERNET-DRAFT R. Even
Intended Status: Standards Track R. Huang
Expires: June 13, 2015 Huawei
L. Deng
China Mobile
December 10, 2014
RTP/RTCP extension for RTP Splicing Notification
draft-ietf-avtext-splicing-notification-01
Abstract
Content splicing is a process that replaces the content of a main
multimedia stream with other multimedia content, and delivers the
substitutive multimedia content to the receivers for a period of
time. The splicer is designed to handle RTP splicing and needs to
know when to start and end the splicing.
This memo defines two RTP/RTCP extensions to indicate the splicing
related information to the splicer: an RTP header extension that
conveys the information in-band and an RTCP packet that conveys the
information out-of-band.
Status of this Memo
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Copyright and License Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
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Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Overview of RTP Splicing Notification . . . . . . . . . . . . . 4
3 Conveying Splicing Interval in RTP/RTCP extensions . . . . . . 5
3.1 RTP Header Extension . . . . . . . . . . . . . . . . . . . . 5
3.2 RTCP Splicing Notification Message . . . . . . . . . . . . . 6
4 Reducing Splicing Latency . . . . . . . . . . . . . . . . . . . 7
5 Failure Cases . . . . . . . . . . . . . . . . . . . . . . . . . 8
6 SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.1 Declarative SDP . . . . . . . . . . . . . . . . . . . . . . 9
6.2 Offer/Answer without BUNDLE . . . . . . . . . . . . . . . . 9
6.3 Offer/Answer with BUNDLE: All Media are spliced . . . . . . 10
6.4 Offer/Answer with BUNDLE: a Subset of Media are Spliced . . 12
7 Security Considerations . . . . . . . . . . . . . . . . . . . . 13
8 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 14
8.1 RTCP Control Packet Types . . . . . . . . . . . . . . . . . 14
8.2 RTP Compact Header Extensions . . . . . . . . . . . . . . . 14
8.3 SDP Grouping Semantic Extension . . . . . . . . . . . . . . 14
9 Acknowledges . . . . . . . . . . . . . . . . . . . . . . . . . . 15
10 References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
10.1 Normative References . . . . . . . . . . . . . . . . . . . 15
10.2 Informative References . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16
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1 Introduction
Splicing is a process that replaces some multimedia content with
other multimedia content and delivers the substitutive multimedia
content to the receivers for a period of time. In some predictable
splicing cases, e.g., advertisement insertion, the splicing duration
MUST be inside of the specific, pre-designated time slot. Certain
timing information about when to start and end the splicing must be
first acquired by the splicer in order to start the splicing. This
document refers to this information as Splicing Interval.
[SCTE35] provides a method that encapsulates the Splicing Interval
inside the MPEG2-TS layer in cable TV systems. But in the RTP
splicing scenario described in [RFC6828], the RTP mixer designed as
the splicer has to decode the RTP packets and search for the Splicing
Interval inside the payloads. The need for such processing increases
the workload of the mixer and limits the number of RTP sessions the
mixer can support.
The document defines an RTP header extension [RFC5285] used by the
main RTP sender to provide the Splicing Interval by including it in
the RTP packets.
Nevertheless, the Splicing Interval conveyed in the RTP header
extension might not reach the mixer successfully, any splicing un-
aware middlebox on the path between the RTP sender and the mixer
might strip this RTP header extension.
To increase robustness against such case, the document also defines a
new RTCP packet type in a complementary fashion to carry the same
Splicing Interval to the mixer.
1.1 Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
The terminology defined in "Content Splicing for RTP Sessions"
[RFC6828] applies to this document and in addition, we define:
Splicing Interval:
The NTP timestamps for the Splicing-In point and Splicing-Out
point per [RFC6828] allowing the mixer to know when to start and
end the RTP splicing.
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2 Overview of RTP Splicing Notification
According to RTP Splicing draft [RFC6828], a mixer is designed to
handle splicing on the RTP layer at the reserved time slots set by
the main RTP sender. This implies that the mixer must first know the
Splicing Interval from the main RTP sender before it can start
splicing.
When a new splicing is forthcoming, the main RTP sender MUST send the
Splicing Interval to the mixer. Usually, the Splicing Interval SHOULD
be sent more than once to mitigate the possible packet loss. To
enable the mixer to get the substitutive content before the splicing
starts, the main RTP sender MUST send the Splicing Interval far
ahead. For example, the main RTP sender can estimate when to send the
Splicing Interval based on the round-trip time (RTT) following the
mechanisms in section 6.4.1 of [RFC3550] when the mixer sends RTCP RR
to the main sender.
The substitutive sender also needs to learn the Splicing Interval
from the main RTP sender in advance, and thus estimates when to
transfer the substitutive content to the mixer. The Splicing Interval
could be transmitted from the main RTP sender to the substitutive
content using some out-of-band mechanisms, the details how to achieve
that are beyond the scope of this memo. To ensure the Splicing
Interval is valid for both the main RTP sender and the substitutive
RTP sender, the two senders MUST share a common reference clock, so
the mixer can achieve accurate splicing.
In this document, the main RTP sender uses a couple of NTP-format
timestamps, derived from the common reference clock, to indicate when
to start and end the splicing to the mixer: the timestamp of the
first substitutive RTP packet at the splicing in point, and the
timestamp of the first main RTP packet at the splicing out point.
When the substitutive RTP sender gets the Splicing Interval, it must
prepare the substitutive stream. The mixer MUST ensure that the RTP
timestamp of the first substitutive RTP packet that would be
presented to the receivers corresponds to the same time instant as
the former NTP timestamp in the Splicing Interval. To enable the
mixer to know the first substitutive RTP packet it needs to send, the
substitutive RTP sender MUST send the substitutive RTP packet ahead
of the Splicing In point, sllowing the mixer to find out the
timestamp of this first RTP packet in the substitutive RTP stream,
e.g., using a prior RTCP SR message.
When the splicing will end, the mixer MUST ensure that the RTP
timestamp of the first main RTP packet that would be presented on the
receivers corresponds to the same time instant as the latter NTP
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timestamp in the Splicing Interval.
3 Conveying Splicing Interval in RTP/RTCP extensions
This memo defines two backwards compatible RTP extensions to convey
the Splicing Interval to the mixer: an RTP header extension and an
RTCP splicing notification message.
3.1 RTP Header Extension
The RTP header extension mechanism defined in [RFC5285] can be
adapted to carry the Splicing Interval consisting of a couple of NTP-
format timestamps.
One variant is defined for this header extension. It carries the 7
octets splicing-out NTP timestamp (lower 24-bit part of the Seconds
of a NTP-format timestamp and the 32 bits of the Fraction of a NTP-
format timestamp as defined in [RFC5905]), followed by the 8 octets
splicing-in NTP timestamp (64-bit NTP-format timestamp as defined in
[RFC5905]). The top 8 bits of the splicing-out NTP timestamp are
referred from the top 8 bits of the splicing-in NTP timestamp. This
is unambiguous, under the assumption that the splicing-out time is
after the splicing-in time, and the splicing interval is less than
2^25 seconds.
The format is shown in Figures 1.
0 1 2 3
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0xBE | 0xDE | length=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+E
| ID | L=15 | OUT NTP timestamp format - Seconds (bit 8-31) |x
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+t
| OUT NTP timestamp format - Fraction (bit 0-31) |e
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+n
| IN NTP timestamp format - Seconds (bit 0-31) |s
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+i
| IN NTP timestamp format - Fraction (bit 0-31) |o
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+n
Figure 1: Sample hybrid NTP Encoding Using
the One-Byte Header Format
Note that the inclusion of an RTP header extension will reduce the
efficiency of RTP header compression. It is RECOMMENDED that the main
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sender begins to insert the RTP header extensions into a number of
RTP packets prior to the splicing in, while leaving the remaining RTP
packets unmarked.
After the mixer intercepts the RTP header extension and derives the
Splicing Interval, it will generate its own stream and SHOULD NOT
include the RTP header extension in outgoing packets to reduce header
overhead.
Furthermore, whether the in-band NTP-format timestamps are included
or not, RTCP splicing notification message, specified in the next
section, MUST be sent to provide robustness in case of any splicing-
unaware middlebox that might strip RTP header extensions.
3.2 RTCP Splicing Notification Message
In addition to the RTP header extension, the main RTP sender includes
the Splicing Interval in an RTCP splicing notification message.
The RTCP splicing notification message is a new RTCP packet type. It
has a fix header followed by a couple of NTP-format timestamps:
0 1 2 3
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|V=2|P|reserved | PT=TBA | length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IN NTP Timestamp (most significant word) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IN NTP Timestamp (least significant word) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OUT NTP Timestamp (most significant word) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OUT NTP Timestamp (least significant word) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: RTCP Splicing Notification Message
The RSI packet includes the following fields:
Length: 16 bits
As defined in [RFC3550], the length of the RTCP packet in 32-bit
words minus one, including the header and any padding.
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SSRC: 32 bits
The SSRC of the Main RTP Sender.
Timestamp: 64 bits
Indicates the wallclock time when this splicing starts and ends.
The full-resolution NTP timestamp is used, which is a 64-bit,
unsigned, fixed-point number with the integer part in the first 32
bits and the fractional part in the last 32 bits. This format is
similar to RTCP Sender Report (Section 6.4.1 of [RFC3550]).
The RTCP splicing notification message can be appended to RTCP SR the
main RTP sender generates in compound RTCP packets, and hence follows
the compound RTCP rules defined in Section 6.1 in [RFC3550].
If the use of non-compound RTCP [RFC5506] was previously negotiated
between the sender and the mixer, the RTCP splicing notification
message may be sent as non-compound RTCP packets.
When the mixer intercepts the RTCP splicing notification message, it
MAY NOT forward the message to the receivers in order to reduce RTCP
bandwidth consumption or to avoid downstream receivers from detecting
splicing defined in Section 4.5 in [RFC6828].
4 Reducing Splicing Latency
When splicing starts or ends, the mixer outputs the multimedia
content from another sender to the receivers. Given that the
receivers must first acquire certain information ([RFC6285] refers to
this information as Reference Information) to start processing the
multimedia data, either the main RTP sender or the substitutive
sender SHOULD provide the Reference Information align with its
multimedia content to reduce the delay caused by acquiring the
Reference Information. The methods by which the Reference Information
is distributed to the receivers is out of scope of this memo.
Another latency element is synchronization caused delay. The
receivers must receive enough synchronization metadata prior to
synchronizing the separate components of the multimedia streams when
splicing starts or ends. Either the main RTP sender or the
substitutive sender SHOULD send the synchronization metadata early
enough so that the receivers can play out the multimedia in a
synchronized fashion. The mechanisms defined in [RFC6051] are
RECOMMENDED to be adopted to reduce the possible synchronization
delay.
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5 Failure Cases
This section examines the implications of losing RTCP splicing
notification message and other failure case, e.g., the RTP header
extension is stripped on the path.
Given that there may be splicing un-aware middlebox on the path
between the main RTP sender and the mixer, one heuristics will be
used to verify whether or not the Splicing Interval reaches the
mixers.
If the mixer does not get the Splicing Interval when the splicing
starts, it will still output the main content to the downstream
receivers and forward the RTCP RR packets sent from downstream
receivers to the main RTP sender (see section 4.2 of [RFC6828]). In
such case, the main RTP sender can learn that splicing failed.
In a similar manner, the substitutive sender can learn that splicing
failed if it does not receive any RTCP RR packets from downstream
receivers when the splicing starts.
Upon the detection of a failure, the main RTP sender or the
substitutive sender SHOULD check the path to the failed mixer, or
fallback to the payload specific mechanisms, e.g., MPEG-TS splicing
solution defined in [SCTE35].
6 SDP Signaling
This document defines the URI for declaring this header extension in
an extmap attribute to be "urn:ietf:params:rtp-hdrext:splicing-
interval".
This document extended the standard semantics defined in SDP Grouping
Framework [RFC5888] with a new semantic: SPLICE to represent the
relationship between the main RTP stream and the substitutive RTP
stream. The main RTP sender provides the information about both main
and substitutive sources.
The extended SDP attribute specified in this document is applicable
for offer/answer content [RFC3264] and do not affect any rules when
negotiating offer and answer. When used with multiple media,
substitutive RTP MUST be applied only to the RTP packets whose SDP m-
line is in the same group with the substitutive stream using FID and
has the extended splicing extmap attribute. This semantics is to have
splicing applicable for BUNDLE cases.
The following examples show how SDP signaling could be used for
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splicing in different cases.
6.1 Declarative SDP
v=0
o=xia 1122334455 1122334466 IN IP4 splicing.example.com
s=RTP Splicing Example
t=0 0
a=group:SPLICE 1 2
m=video 30000 RTP/AVP 100
i=Main RTP Stream
c=IN IP4 233.252.0.1/127
a=rtpmap:100 MP2T/90000
a=extmap:1 urn:ietf:params:rtp-hdrext:splicing-interval
a=mid:1
m=video 30002 RTP/AVP 100
i=Substitutive RTP Stream
c=IN IP4 233.252.0.2/127
a=sendonly
a=rtpmap:100 MP2T/90000
a=mid:2
Figure 3: Example SDP for a single-channel splicing scenario
The mixer receiving the SDP message above receives one MPEG2-TS
stream (payload 100) from the main RTP sender (with multicast
destination address of 233.252.0.1) on port 30000, and/or receives
another MPEG2-TS stream from the substitutive RTP sender (with
multicast destination address of 233.252.0.2) on port 30002. But at
a particular point in time, the mixer only selects one stream and
outputs the content from the chosen stream to the downstream
receivers.
6.2 Offer/Answer without BUNDLE
SDP Offer - from main RTP sender
v=0
o=xia 1122334455 1122334466 IN IP4 splicing.example.com
s=RTP Splicing Example
t=0 0
a=group:SPLICE 1 2
m=video 30000 RTP/AVP 31 100
i=Main RTP Stream
c=IN IP4 splicing.example.com
a=rtpmap:31 H261/90000
a=rtpmap:100 MP2T/90000
a=extmap:1 urn:ietf:params:rtp-hdrext:splicing-interval
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a=mid:1
m=video 40000 RTP/AVP 31 100
i=Substitutive RTP Stream
c=IN IP4 substitutive.example.com
a=rtpmap:31 H261/90000
a=rtpmap:100 MP2T/90000
a=sendonly
a=mid:2
SDP Answer - from splicer
v=0
o=xia 1122334455 1122334466 IN IP4 splicer.example.com
s=RTP Splicing Example
t=0 0
a=group:SPLICE 1 2
m=video 30000 RTP/AVP 100
i=Main RTP Stream
c=IN IP4 splicer.example.com
a=rtpmap:100 MP2T/90000
a=extmap:1 urn:ietf:params:rtp-hdrext:splicing-interval
a=mid:1
m=video 40000 RTP/AVP 100
i=Substitutive RTP Stream
c=IN IP4 splicer.example.com
a=rtpmap:100 MP2T/90000
a=recvonly
a=mid:2
Only codecs that are supported both by the main RTP stream and the
substitutive RTP stream could be negotiated with SDP O/A. And the
mixer MUST choose the same codec for both of these two streams.
6.3 Offer/Answer with BUNDLE: All Media are spliced
In this example, the bundled audio and video media have their own
substitutive media for splicing:
1. An Offer, in which the offerer assigns a unique address and a
substitutive media to each bundled "m="line for splicing within the
BUNDLE group.
2. An answer, in which the answerer selects its own BUNDLE address,
and leave the substitutive media untouched.
SDP Offer - from main RTP sender
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v=0
o=alice 1122334455 1122334466 IN IP4 splicing.example.com
s=RTP Splicing Example
c=IN IP4 splicing.example.com
t=0 0
a=group:SPLICE foo 1
a=group:SPLICE bar 2
a=group:BUNDLE foo bar
m=audio 10000 RTP/AVP 0 8 97
a=mid:foo
b=AS:200
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:97 iLBC/8000
a=extmap:1 urn:ietf:params:rtp-hdrext:splicing-interval
m=video 10002 RTP/AVP 31 32
a=mid:bar
b=AS:1000
a=rtpmap:31 H261/90000
a=rtpmap:32 MPV/90000
a=extmap:2 urn:ietf:params:rtp-hdrext:splicing-interval
m=audio 20000 RTP/AVP 0 8 97
i=Substitutive audio RTP Stream
c=IN IP4 substitive.example.com
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:97 iLBC/8000
a=sendonly
a=mid:1
m=video 20002 RTP/AVP 31 32
i=Substitutive video RTP Stream
c=IN IP4 substitive.example.com
a=rtpmap:31 H261/90000
a=rtpmap:32 MPV/90000
a=mid:2
SDP Answer - from the splicer
v=0
o=bob 2808844564 2808844564 IN IP4 splicer.example.com
s=RTP Splicing Example
c=IN IP4 splicer.example.com
t=0 0
a=group:SPLICE foo 1
a=group:SPLICE bar 2
a=group:BUNDLE foo bar
m=audio 30000 RTP/AVP 0
a=mid:foo
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b=AS:200
a=rtpmap:0 PCMU/8000
a=extmap:1 urn:ietf:params:rtp-hdrext:splicing-interval
m=video 30000 RTP/AVP 32
a=mid:bar
b=AS:1000
a=rtpmap:32 MPV/90000
a=extmap:2 urn:ietf:params:rtp-hdrext:splicing-interval
m=audio 30002 RTP/AVP 0
i=Substitutive audio RTP Stream
c=IN IP4 splicer.example.com
a=rtpmap:0 PCMU/8000
a=sendonly
a=mid:1
m=video 30004 RTP/AVP 32
i=Substitutive video RTP Stream
c=IN IP4 splicer.example.com
a=rtpmap:32 MPV/90000
a=mid:2
6.4 Offer/Answer with BUNDLE: a Subset of Media are Spliced
In this example, the substitutive media only applies for video when
splicing:
1. An Offer, in which the offerer assigns a unique address to each
bundled "m="line within the BUNDLE group, and assigns a substitutive
media to the bundled video "m=" line for splicing.
2. An answer, in which the answerer selects its own BUNDLE address,
and leave the substitutive media untouched.
SDP Offer - from the main RTP sender:
v=0
o=alice 1122334455 1122334466 IN IP4 splicing.example.com
s=RTP Splicing Example
c=IN IP4 splicing.example.com
t=0 0
a=group:SPLICE bar 2
a=group:BUNDLE foo bar
m=audio 10000 RTP/AVP 0 8 97
a=mid:foo
b=AS:200
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:97 iLBC/8000
m=video 10002 RTP/AVP 31 32
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a=mid:bar
b=AS:1000
a=rtpmap:31 H261/90000
a=rtpmap:32 MPV/90000
a=extmap:2 urn:ietf:params:rtp-hdrext:splicing-interval
m=video 20000 RTP/AVP 31 32
i=Substitutive video RTP Stream
c=IN IP4 substitutive.example.com
a=rtpmap:31 H261/90000
a=rtpmap:32 MPV/90000
a=mid:2
SDP Answer - from the splicer:
v=0
o=bob 2808844564 2808844564 IN IP4 splicer.example.com
s=RTP Splicing Example
c=IN IP4 splicer.example.com
t=0 0
a=group:SPLICE bar 2
a=group:BUNDLE foo bar
m=audio 30000 RTP/AVP 0
a=mid:foo
b=AS:200
a=rtpmap:0 PCMU/8000
m=video 30000 RTP/AVP 32
a=mid:bar
b=AS:1000
a=rtpmap:32 MPV/90000
a=extmap:2 urn:ietf:params:rtp-hdrext:splicing-interval
m=video 30004 RTP/AVP 32
i=Substitutive video RTP Stream
c=IN IP4 splicer.example.com
a=rtpmap:32 MPV/90000
a=mid:2
7 Security Considerations
The security considerations of the RTP specification [RFC3550], the
general mechanism for RTP header extensions [RFC5285] and the
security considerations of the RTP splicing specification [RFC6828]
apply.
The RTP header extension defined in Section 4.1 include two NTP-
format timestamps. In the Secure Real-time Transport Protocol
(SRTP)[RFC3711], RTP header extensions are authenticated but not
encrypted. A malicious endpoint possessing the SRTP key could choose
to set the values in this header extension falsely, so as to falsely
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claim the splicing time. Also, such a malicious endpoint could cause
any arbitrary content it wishes spliced into the main RTP stream.
In scenarios where this is a concern, additional mechanisms MUST be
used to protect the confidentiality of the header extension. This
mechanism could be header extension encryption [SRTP-ENCR-HDR], or a
lower-level security and authentication mechanism such as IPsec
[RFC4301].
8 IANA Considerations
8.1 RTCP Control Packet Types
Based on the guidelines suggested in [RFC5226], a new RTCP packet
format has been registered with the RTCP Control Packet Type (PT)
Registry:
Name: SNM
Long name: Splicing Notification Message
Value: TBA
Reference: This document
8.2 RTP Compact Header Extensions
The IANA has also registered a new RTP Compact Header Extension
[RFC5285], according to the following:
Extension URI: urn:ietf:params:rtp-hdrext:splicing-interval
Description: Splicing Interval
Contact: Jinwei Xia <xiajinwei@huawei.com>
Reference: This document
8.3 SDP Grouping Semantic Extension
This document request IANA to register the new SDP grouping semantic
extension called "SPLICE".
Semantics: Splice
Token:SPLICE
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Reference: This document
Contact: Jinwei Xia <xiajinwei@huawei.com>
9 Acknowledges
TBD
10 References
10.1 Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, July 2003.
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, July 2006.
[RFC5285] Singer, D. and H. Desineni, "A General Mechanism for RTP
Header Extensions", RFC 5285, July 2008.
[RFC5888] Camarillo, G. and H. Schulzrinne, "The Session Description
Protocol (SDP) Grouping Framework", RFC 5888, June 2010.
[RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,
"Network Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, June 2010.
[RFC6051] Perkins, C. and T. Schierl, "Rapid Synchronisation of RTP
Flows", RFC 6051, November 2010.
[RFC6828] Xia, J., "Content Splicing for RTP Sessions", RFC 6828,
January 2013.
10.2 Informative References
[RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
Norrman, "The Secure Real-time Transport Protocol (SRTP)",
RFC 3711, March 2004.
[RFC4301] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, December 2005.
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[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC5506] Johansson, I. and M. Westerlund, "Support for Reduced-Size
Real-Time Transport Control Protocol (RTCP): Opportunities
and Consequences", RFC 5506, April 2009.
[RFC6285] Ver Steeg, B., Begen, A., Van Caenegem, T., and Z. Vax,
"Unicast-Based Rapid Acquisition of Multicast RTP
Sessions", RFC 6285, June 2011.
[RFC6904] Lennox, J.,"Encryption of Header Extensions in the Secure
Real-Time Transport Protocol (SRTP)", April 2013.
[SCTE35] Society of Cable Telecommunications Engineers (SCTE),
"Digital Program Insertion Cueing Message for Cable",
2011.
Authors' Addresses
Jinwei Xia
Huawei
Email: xiajinwei@huawei.com
Roni Even
Huawei
Email: ron.even.tlv@gmail.com
Rachel Huang
Huawei
Email: rachel.huang@huawei.com
Lingli Deng
China Mobile
Email: denglingli@chinamobile.com
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