draft-ietf-avtext-splicing-notification-05.txt   draft-ietf-avtext-splicing-notification-06.txt 
AVTEXT Working Group J. Xia AVTEXT Working Group J. Xia
INTERNET-DRAFT R. Even INTERNET-DRAFT R. Even
Intended Status: Standards Track R. Huang Intended Status: Standards Track R. Huang
Expires: September 22, 2016 Huawei Expires: October 8, 2016 Huawei
L. Deng L. Deng
China Mobile China Mobile
March 21, 2016 April 6, 2016
RTP/RTCP extension for RTP Splicing Notification RTP/RTCP extension for RTP Splicing Notification
draft-ietf-avtext-splicing-notification-05 draft-ietf-avtext-splicing-notification-06
Abstract Abstract
Content splicing is a process that replaces the content of a main Content splicing is a process that replaces the content of a main
multimedia stream with other multimedia content, and delivers the multimedia stream with other multimedia content, and delivers the
substitutive multimedia content to the receivers for a period of substitutive multimedia content to the receivers for a period of
time. The splicer is designed to handle RTP splicing and needs to time. The splicer is designed to handle RTP splicing and needs to
know when to start and end the splicing. know when to start and end the splicing.
This memo defines two RTP/RTCP extensions to indicate the splicing This memo defines two RTP/RTCP extensions to indicate the splicing
skipping to change at page 6, line 6 skipping to change at page 6, line 6
3 Conveying Splicing Interval in RTP/RTCP extensions 3 Conveying Splicing Interval in RTP/RTCP extensions
This memo defines two backwards compatible RTP extensions to convey This memo defines two backwards compatible RTP extensions to convey
the Splicing Interval to the splicer: an RTP header extension and an the Splicing Interval to the splicer: an RTP header extension and an
RTCP splicing notification message. RTCP splicing notification message.
3.1 RTP Header Extension 3.1 RTP Header Extension
The RTP header extension mechanism defined in [RFC5285] can be The RTP header extension mechanism defined in [RFC5285] can be
adapted to carry the Splicing Interval consisting of a pair of NTP- adapted to carry the Splicing Interval consisting of a pair of NTP-
format timestamps. Two variants are defined for this header format timestamps.
extension: one-byte header variant and two-byte header variant.
For one-byte header variant, it carries the 7 octets splicing-out This RTP header extension carries the 6 octets splicing-out NTP-
NTP-format timestamp (lower 24-bit part of the Seconds of a NTP- format timestamp (lower 16-bit part of the Seconds of a NTP-format
format timestamp and the 32 bits of the Fraction of a NTP-format timestamp and the 32 bits of the Fraction of a NTP-format timestamp
timestamp as defined in [RFC5905]), followed by the 8 octets as defined in [RFC5905]), followed by the 8 octets splicing-in NTP-
splicing-in NTP-format timestamp (64-bit NTP-format timestamp as format timestamp (64-bit NTP-format timestamp as defined in
defined in [RFC5905]). The top 8 bits of the splicing-out NTP [RFC5905]). The top 16 bits of the splicing-out NTP timestamp are
timestamp are inferred from the top 8 bits of the splicing-in NTP inferred from the top 16 bits of the splicing-in NTP timestamp, under
timestamp. This is unambiguous, under the assumption that the the assumption that the splicing-out time is after the splicing-in
splicing-out time is after the splicing-in time, and the splicing time, and the splicing interval is less than 2^16 seconds. Therefore,
interval is less than 2^25 seconds. Therefore, if the value of 7 if the value of 6 octets splicing-out NTP-format timestamp is smaller
octets splicing-out NTP-format timestamp is smaller than the value of than the value of 6 lower octets splicing-in NTP-format, it implies a
7 lower octets splicing-in NTP-format, it implies a wrap of the 56- wrap of the 48-bit splicing-out NTP-format timestamp which means the
bit splicing-out NTP-format timestamp which means the top 8-bit value top 16-bit value of the 64-bit splicing-out is equal to the top 16-
of the 64-bit splicing-out is equal to the top 8-bit value of bit value of splicing-in NTP Timestamp plus 0x0001. Otherwise, the
splicing-in NTP Timestamp plus 0x01. Otherwise, the top 8 bits of top 16 bits of splicing-out NTP timestamp is equal to the top 16 bits
splicing-out NTP timestamp is equal to the top 8 bits of splicing-in of splicing-in NTP Timestamp.
NTP Timestamp.
The format is shown in Figures 1. This RTP header extension can be encoded using either the one-byte or
two-byte header defined in [RFC5285]. Figure 1 and 2 show the
splicing interval header extension with each of the two header
formats.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+E +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+E
| ID | L=15 | OUT NTP timestamp format - Seconds (bit 8-31) |x | ID | L=13 |OUT NTP timestamp-Seconds(0-16)| Out |x
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+t +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+t
| OUT NTP timestamp format - Fraction (bit 0-31) |e | NTP timestamp format - Fraction (bit 0-31) | In |e
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+n +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+n
| IN NTP timestamp format - Seconds (bit 0-31) |s | NTP timestamp format - Seconds (bit 0-31) | In |s
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+i +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+i
| IN NTP timestamp format - Fraction (bit 0-31) |o | NTP timestamp format - Fraction (bit 0-31) | 0 (pad) |o
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+n +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+n
Figure 1: Splicing Interval Figure 1: Splicing Interval
Using the One-Byte Header Format Using the One-Byte Header Format
For two-byte header variant, it carries the 6 octets splicing-out
NTP-format timestamp (lower 16-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-format timestamp (64-bit NTP-format timestamp as
defined in [RFC5905]). Also, the top 16 bits of the splicing-out NTP
timestamp are inferred from the top 16 bits of the splicing-in NTP
timestamp, under the assumption that the splicing-out time is after
the splicing-in time, and the splicing interval is less than 2^16
seconds. Similar to the one-byte header, if the value of 6 octets
splicing-out NTP-format timestamp is smaller than the value of 6
lower octets splicing-in NTP-format, it implies a wrap of the 48-bit
splicing-out NTP-format timestamp which means the top 16-bit value of
the 64-bit splicing-out is equal to the top 16-bit value of splicing-
in NTP Timestamp plus 0x01. Otherwise, the top 16 bits of splicing-
out NTP timestamp is equal to the top 16 bits of splicing-in NTP
Timestamp.
The format is shown in Figures 2.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+E +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+E
| ID | L=14 | OUT NTP timestamp - Seconds |x | ID | L=14 | OUT NTP timestamp - Seconds |x
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+t +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+t
| OUT NTP timestamp format - Fraction (bit 0-31) |e | OUT NTP timestamp format - Fraction (bit 0-31) |e
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+n +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+n
| IN NTP timestamp format - Seconds (bit 0-31) |s | IN NTP timestamp format - Seconds (bit 0-31) |s
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+i +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+i
| IN NTP timestamp format - Fraction (bit 0-31) |o | IN NTP timestamp format - Fraction (bit 0-31) |o
 End of changes. 11 change blocks. 
47 lines changed or deleted 28 lines changed or added

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