One document matched: draft-ietf-payload-rfc3189bis-00.xml
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<rfc category="std" docName="draft-ietf-payload-rfc3189bis-00" ipr="trust200902" obsoletes="3189">
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<!-- ***** FRONT MATTER ***** -->
<front>
<!-- The abbreviated title is used in the page header - it is only necessary if the
full title is longer than 39 characters -->
<title abbrev="RTP Payload Format for DV Video">
RTP Payload Format for DV (IEC 61834) Video
</title>
<!-- add 'role="editor"' below for the editors if appropriate -->
<!-- Another author who claims to be an editor -->
<author fullname="Katsushi Kobayashi" initials="K.K." surname="Kobayashi">
<organization abbrev="AICS, RIKEN">
Advanced Institute for Computational Science, RIKEN
</organization>
<address>
<postal>
<street>7-1-26 Minatojima-minami</street>
<!-- Reorder these if your country does things differently -->
<city>Chuo-ku, Kobe-city</city>
<region>Hyogo</region>
<code>760-0045</code>
<country>Japan</country>
</postal>
<email>ikob@riken.jp</email>
<!-- uri and facsimile elements may also be added -->
</address>
</author>
<author fullname="Kazuhiro Mishima" initials="K.M." surname="Mishima">
<organization abbrev="Keio University">
Keio University
</organization>
<address>
<postal>
<street>5322 Endo</street>
<city>Fujisawa-city</city>
<region>Kanagawa</region>
<code>252-8520</code>
<country>Japan</country>
</postal>
<email>three@sfc.wide.ad.jp</email>
</address>
</author>
<author fullname="Stephen L. Casner" initials="S.C." surname="Casner">
<organization abbrev="Packet Design">
Packet Design
</organization>
<address>
<postal>
<street>2465 Latham Street</street>
<city>Mountain View</city>
<region>CA</region>
<code>94040</code>
<country>United States</country>
</postal>
<email>casner@acm.org</email>
</address>
</author>
<author fullname="Carsten Bormann" initials="C.B." surname="Bormann">
<organization abbrev="Universitaet Bremen TZI">
Universitaet Bremen TZI
</organization>
<address>
<postal>
<street>Postfach 330440</street>
<city>D-28334</city>
<region>Bremen</region>
<code></code>
<country>Germany</country>
</postal>
<phone>+49 421 218 63921</phone>
<facsimile>+49 421 218 7000</facsimile>
<email>cabo@tzi.org</email>
</address>
</author>
<date/>
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<area>General</area>
<workgroup>Network Working Group</workgroup>
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<keyword>DV/RTP</keyword>
<!-- Keywords will be incorporated into HTML output
files in a meta tag but they have no effect on text or nroff
output. If you submit your draft to the RFC Editor, the
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<abstract>
<t>This document specifies the packetization scheme for encapsulating
the compressed digital video data streams commonly known as "DV" into
a payload format for the Real-Time Transport Protocol (RTP). This
document obsoletes RFC 3189.</t>
</abstract>
</front>
<!-- ***** MIDDLE MATTER ***** -->
<middle>
<section title="Introduction">
<t>This document specifies payload formats for encapsulating both
consumer- and professional use DV format data streams into the Real-
time Transport Protocol (RTP) <xref target="RFC3550"/>. DV compression audio
and video formats were designed for a recording format on helical-scan
magnetic tape media. The DV standards for consumer-market
devices, the IEC 61883 and 61834 series, cover many aspects of
consumer-use digital video, including mechanical specifications of a
cassette, magnetic recording format, error correction on the magnetic
tape, DCT video encoding format, and audio encoding format <xref target="IEC61834"/>. The
digital interface part of IEC 61883 defines an interface on IEEE 1394
system <xref target="IEC61883"/><xref target="IEEE1394"/>. This specification set supports several video
formats: SD-VCR (Standard Definition), HD-VCR (High Definition), SDL-VCR
(Standard Definition - Long), PALPlus, DVB (Digital Video
Broadcast) and ATV (Advanced Television). North American formats are
indicated with a number of lines and "/60", while European formats
use "/50". DV standards extended for professional use were published
by SMPTE as 314M and 370M, for different sampling systems, higher
color resolution, and higher bit rates <xref target="SMPTE314M"/><xref target="SMPTE370M"/>.</t>
<t>In summary, there are two kinds of DV, one for consumer use and the other for
professional. The original "DV" specification designed for consumer use
digital VCRs is approved as the IEC 61834 standard set. The
specifications for professional DV are published as SMPTE 314M and
370M. Both encoding formats are based on consumer DV and used in
SMPTE D-7, D-9, and D-12 video systems. The RTP payload format
specified in this document supports IEC 61834 consumer DV and
professional SMPTE 314M and 370M (DV-Based) formats.</t>
<t>IEC 61834 also includes magnetic tape recording for digital TV
broadcasting systems (such as DVB and ATV) that use MPEG2 encoding.
The payload format for encapsulating MPEG2 into RTP has already been
defined in RFC 2250 <xref target="RFC2250"/> and others.</t>
<t>Consequently, the payload specified in this document will support six
video formats of the IEC standard: SD-VCR (525/60, 625/50), HD-VCR
(1125/60, 1250/50) and SDL-VCR (525/60, 625/50), and seven of the
SMPTE standards: 314M 25Mbps (525/60, 625/50), 314M 50Mbps (525/60,
625/50), and 370M 100Mbps (1080/60i, 1080/50i, 720/60p, and 720/50p).
In the future it can be extended into other video formats managed by
80 byte DV DIF block.</t>
<t>In the future it can be extended into other video formats that are
based on DV's 80-byte DIF blocks. Throughout this specification, we make
extensive use of the terminology of IEC and SMPTE standards. The reader
should consult the original references for definitions of these terms.</t>
<section title="Terminology">
<t>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 <xref target="RFC2119"/>.</t>
</section>
</section>
<section title="RTP Payload Format">
<section title="The DV Format Encoding">
<t>The DV format only uses the DCT compression technique within each
frame, contrasted with the interframe compression of the MPEG video
standards <xref target="ISO/IEC11172"/><xref target="ISO/IEC13818"/>.
All video data, including audio and other system
data, are managed within the picture frame unit of video.</t>
<t>The DV video encoding is composed of a three-level hierarchical
structure, i.e., DCT super block, DCT macro block, and DCT block. A
picture frame is divided into rectangle- or clipped-rectangle-shaped
DCT super blocks. DCT super blocks are divided into 27 rectangle- or
square-shaped DCT macro blocks, and each DCT macro block consists of
a number of DCT blocks. Each DCT block represents a rectangle region
for each color (Y, Cb, and Cr), and each DCT block consists of 8x8
pixels.</t>
<t>Audio data is encoded in PCM format. The sampling frequency is 32
kHz, 44.1 kHz or 48 kHz and the quantization is 12-bit non-linear,
16-bit linear or 20-bit linear. The number of channels may be up to
8. Only certain combinations of these parameters are allowed
depending upon the video format; the restrictions are specified in
each document.</t>
<t>A frame of data in the DV format stream is divided into several "DIF
sequences". A DIF sequence is composed of an integral number of 80-
byte DIF blocks. A DIF block is the primitive unit for all treatment
of DV streams. Each DIF block contains a 3-byte ID header that
specifies the type of the DIF block and its position in the DIF
sequence. Five types of DIF blocks are defined: DIF sequence header,
Subcode, Video Auxiliary information (VAUX), Audio, and Video. Audio
DIF blocks are composed of 5 bytes of Audio Auxiliary data (AAUX) and
72 bytes of audio data.</t>
<t>Each RTP packet starts with the RTP header as defined in RFC 3550
<xref target="RFC3550"/>. No additional payload-format-specific header
is required for this payload format.</t>
</section>
<section title="RTP Header Usage">
<t>The RTP header fields that have a meaning specific to the DV format
are described as follows:</t>
<t>Payload type (PT): The payload type is dynamically assigned by means
outside the scope of this document. If multiple DV encoding formats
are to be used within one RTP session, then multiple dynamic payload
types MUST be assigned, one for each DV encoding format. The sender
MUST change to the corresponding payload type whenever the encoding
format is changed.</t>
<t>Timestamp: 32-bit 90 kHz timestamp representing the time at which the
first data in the frame was sampled. All RTP packets within the same
video frame MUST have the same timestamp. The timestamp SHOULD
increment by a multiple of the nominal interval for one DV frame time,
as given in the following table:</t>
<texttable>
<ttcol align='center'>Mode</ttcol>
<ttcol align='center'>Frame rate (Hz)</ttcol>
<ttcol align='center'>Increase of one DV frame in 90kHz timestamp</ttcol>
<c>525-60</c> <c>29.97</c> <c>3003</c>
<c>625-50</c> <c>25</c> <c>3600</c>
<c>1125-60</c> <c>30</c> <c>3000</c>
<c>1250-50</c> <c>25</c> <c>3600</c>
<c>1080-60i</c> <c>29.97</c> <c>3003</c>
<c>1080-50i</c> <c>25</c> <c>3600</c>
<c>720-60p</c> <c>59.94</c> <c>3003(*)</c>
<c>720-50p</c> <c>50</c> <c>3600(*)</c>
</texttable>
<t>Note that even in the 720-line DV system, the data in two video frames
shall be processed within one DV frame duration of the 1080-line system.
Audio data and subcode data in the 720-line system are processed in the
same way as the 1080-line system. Therefore in the 720-line system, the
increase of one DV frame corresponds two video frames time.</t>
<t>Marker bit (M): The marker bit of the RTP fixed header is set to one
on the last packet of a video frame, and otherwise, must be zero.
The M bit allows the receiver to know that it has received the last
packet of a frame so it can display the image without waiting for the
first packet of the next frame to arrive to detect the frame change.
However, detection of a frame change MUST NOT rely on the marker bit
since the last packet of the frame might be lost. Detection of a
frame change MUST be based on a difference in the RTP timestamp.</t>
</section>
<section title="Payload Structures">
<t>Integral DIF blocks are placed into the RTP payload beginning
immediately after the RTP header. Any number of DIF blocks may be
packed into one RTP packet, except that all DIF blocks in one RTP
packet MUST be from the same video frame. DIF blocks from the next
video frame MUST NOT be packed into the same RTP packet even if more
payload space remains. This requirement stems from the fact that the
transition from one video frame to the next is indicated by a change
in the RTP timestamp. It also reduces the processing complexity on
the receiver. Since the RTP payload contains an integral number of
DIF blocks, the length of the RTP payload will be a multiple of 80
bytes.</t>
<t>Audio and video data may be transmitted as one bundled RTP stream or
in separate RTP streams (unbundled). The choice MUST be indicated as
part of the assignment of the dynamic payload type and MUST remain
unchanged for the duration of the RTP session to avoid complicated
procedures of sequence number synchronization. The RTP sender could
omit DIF-sequence header and subcode DIF blocks from a stream, when
the information either is known out-of-band or is not
required for the application. Note that time code in DIF blocks is
mandatory for professional video applications. When sending DIF-
sequence header and subcode DIF blocks with unbundled audio and video
streams, both types of blocks MUST be included in the video stream.</t>
<t>DV streams include "source" and "source control" packs that carry
information indispensable for proper decoding, such as video signal
type, frame rate, aspect ratio, picture position, quantization of
audio sampling, number of audio samples in a frame, number of audio
channels, audio channel assignment, and language of the audio.
However, describing all of these attributes with a signaling protocol
would require large descriptions to enumerate all the combinations.
Therefore, no Session Description Protocol (SDP)
<xref target="RFC4566"/> parameters for these attributes are defined
in this document. Instead, the RTP sender MUST transmit at least
those VAUX (Video AUXiliary) DIF blocks and/or audio DIF blocks with
AAUX (Audio AUXiliary) information bytes that include "source" and
"source control" packs containing the indispensable information for
decoding.</t>
<t>In the case of one bundled stream, DIF blocks for both audio and
video are packed into RTP packets in the same order as they were
encoded.</t>
<t>In the case of an unbundled stream, only the header, subcode, video
and VAUX DIF blocks are sent within the video stream. Audio is sent
in a different stream if desired, using a different RTP payload type.
It is also possible to send audio duplicated in a separate
stream, in addition to bundling it in with the video stream.</t>
<t>When using unbundled mode, it is RECOMMENDED that the audio stream
data be extracted from the DIF blocks and repackaged into the
corresponding RTP payload format for the audio encoding (DAT12, L16,
L20) <xref target="RFC3551"/><xref target="RFC3190"/> in order to
maximize interoperability with non-DV-capable receivers while
maintaining the original source quality.</t>
<t>In the case of unbundled transmission which is
compelled to use both audio and video in the DV format, the same
timestamp SHOULD be used for both
audio and video data within the same frame to simplify the lip
synchronization effort on the receiver. Lip synchronization may also
be achieved using reference timestamps passed in RTCP as described in
RFC 3550. In this case, the audio stream uses the 90kHz clock
rate, and the timestamp uses the same clock rate as the video.</t>
<t>The sender MAY reduce the video frame rate by discarding the video
data and VAUX DIF blocks for some of the video frames. The RTP
timestamp MUST still be incremented to account for the discarded
frames. The sender MAY alternatively reduce bandwidth by discarding
video data DIF blocks for portions of the image which are unchanged
from the previous image. To enable this bandwidth reduction,
receivers SHOULD implement an error concealment strategy to
accommodate lost or missing DIF blocks, e.g., repeating the
corresponding DIF block from the previous image.</t>
</section>
</section>
<section title="Payload Format Parameters">
<t>This section specifies the parameters that MAY be used to select
optional features of the payload format and certain features of the
bitstream. The parameters are specified here as part of the media
type registration for the DV encoding. A mapping of the parameters
into the Session Description Protocol (SDP) <xref target="RFC4566"/> is also
provided for applications that use SDP. Equivalent parameters could
be defined elsewhere for use with control protocols that do not use
SDP.</t>
<section title="Media Type Registration" anchor="reg_form">
<t>This registration is done using the template defined in RFC 4288
<xref target="RFC4288"/> and following RFC 4855 <xref target="RFC4855"/>.</t>
<section title="Media Type Registration for DV Video">
<t>
<list style='hanging'>
<t hangText="Type name:">video</t>
<t hangText="Subtype name:">DV</t>
<t hangText="Required parameters:">
<list style='hanging'>
<t hangText="encode:">type of DV format. Permissible values for encode are<vspace />
SD-VCR/525-60,<vspace />
SD-VCR/625-50,<vspace />
HD-VCR/1125-60,<vspace />
HD-VCR/1250-50,<vspace />
SDL-VCR/525-60,<vspace />
SDL-VCR/625-50,<vspace />
314M-25/525-60,<vspace />
314M-25/625-50,<vspace />
314M-50/525-60,<vspace />
314M-50/625-50,<vspace />
370M/1080-60i,<vspace />
370M/1080-50i,<vspace />
370M/720-60p,<vspace />
370M/720-50p,<vspace />
306M/525-60 (for backward compatibility),<vspace />
and 306M/625-50 (for backward compatibility).</t>
</list>
</t>
<t hangText="Optional parameters:">
<list style='hanging'>
<t hangText="audio:">whether the DV stream includes audio data or not.
Permissible values for audio are bundled and none. Defaults to
none.</t>
</list>
</t>
<t hangText="Encoding considerations:">
<list style='empty'>
<t>DV video can be transmitted with RTP as specified in RFCXXXX (This
document).
Other transport methods are not specified.</t>
</list>
</t>
<t hangText="Security considerations:">
<list style='empty'>
<t>See <xref target="sec_cons"/> of RFCXXXX (This document).</t>
</list>
</t>
<t hangText="Interoperability considerations:">NONE</t>
<t hangText="Public specification:">
<list style='empty'>
<t>IEC 61834 Standard<vspace />
SMPTE 314M<vspace />
SMPTE 370M<vspace />
RFCXXXX (This document)<vspace />
SMPTE 306M (for backward compatibility).</t>
</list>
</t>
<t hangText="Applications that use this media type:">
Audio and video streaming and conferencing tools.</t>
<t hangText="Additional information:">NONE</t>
<t hangText="Person & email address to contact for further information:">
<list style='empty'>
<t>Katsushi Kobayashi</t>
<t>e-mail: ikob@ni.aist.go.jp</t>
</list>
</t>
<t hangText="Intended usage:">COMMON</t>
<t hangText="Restrictions on usage:">
This media type depends on RTP framing, and hence is only
defined for transfer via RTP (RFC 3550). Transfer within
other framing protocols is not defined at this time.</t>
<t hangText="Author:">
<list style='empty'>
<t>Katsushi Kobayashi</t>
</list>
</t>
<t hangText="Change controller:">
<list style='empty'>
<t>IETF Audio/Video Transport working group delegated from the IESG</t>
</list>
</t>
</list>
</t>
</section>
<section title="Media Type Registration for DV Audio">
<t>
<list style='hanging'>
<t hangText="Type name:">audio</t>
<t hangText="Subtype name:">DV</t>
<t hangText="Required parameters:">
<list style='hanging'>
<t hangText="encode:">type of DV format. Permissible values for encode are<vspace />
SD-VCR/525-60,<vspace />
SD-VCR/625-50,<vspace />
HD-VCR/1125-60,<vspace />
HD-VCR/1250-50,<vspace />
SDL-VCR/525-60,<vspace />
SDL-VCR/625-50,<vspace />
314M-25/525-60,<vspace />
314M-25/625-50,<vspace />
314M-50/525-60,<vspace />
314M-50/625-50,<vspace />
370M/1080-60i,<vspace />
370M/1080-50i,<vspace />
370M/720-60p,<vspace />
370M/720-50p,<vspace />
306M/525-60 (for backward compatibility),<vspace />
and 306M/625-50 (for backward compatibility).</t>
</list>
</t>
<t hangText="Optional parameters:">
<list style='hanging'>
<t hangText="audio:">whether the DV stream includes audio data or not.
Permissible values for audio are bundled and none. Defaults to
none.</t>
</list>
</t>
<t hangText="Encoding considerations:">
<list style='empty'>
<t>DV audio can be transmitted with RTP as specified in RFCXXXX (This
document).
Other transport methods are not specified.</t>
</list>
</t>
<t hangText="Security considerations:">
<list style='empty'>
<t>See <xref target="sec_cons"/> of RFCXXXX (This document).</t>
</list>
</t>
<t hangText="Interoperability considerations:">NONE</t>
<t hangText="Published specification:">
<list style='empty'>
<t>IEC 61834 Standard<vspace />
SMPTE 314M<vspace />
SMPTE 370M<vspace />
RFCXXXX (This document)<vspace />
SMPTE 306M (for backward compatibility).</t>
</list>
</t>
<t hangText="Applications that use this media type:">
Audio and video streaming and conferencing tools.</t>
<t hangText="Additional information:">NONE</t>
<t hangText="Person & email address to contact for further information:">
<list style='empty'>
<t>Katsushi Kobayashi</t>
<t>e-mail: ikob@ni.aist.go.jp</t>
</list>
</t>
<t hangText="Intended usage:">COMMON</t>
<t hangText="Restrictions on usage:">
This media type depends on RTP framing, and hence is only
defined for transfer via RTP (RFC 3550). Transfer within
other framing protocols is not defined at this time.</t>
<t hangText="Author:">
<list style='empty'>
<t>Katsushi Kobayashi</t>
</list>
</t>
<t hangText="Change controller:">
<list style='empty'>
<t>IETF Audio/Video Transport working group delegated from the IESG</t>
</list>
</t>
</list>
</t>
</section>
</section>
<section title="SDP Parameters">
<section title="Mapping of Payload Type Parameters to SDP">
<t>The information carried in the media type specification has a
specific mapping to fields in the Session Description Protocol (SDP),
which is commonly used to describe RTP sessions. When SDP is
used to specify sessions employing the DV encoding, the mapping is
as follows:</t>
<t>
<list style='symbols'>
<t>The media type ("video") goes in SDP "m=" as the media name.</t>
<t>The media subtype ("DV") goes in SDP "a=rtpmap" as the encoding
name. The RTP clock rate in "a=rtpmap" MUST be 90000 which for
the payload format defined in this document is a 90kHz clock.</t>
<t>Any remaining parameters go in the SDP "a=fmtp" attribute by
copying them directly from the media type string as a semicolon
separated list of parameter=value pairs.</t>
</list>
</t>
<t>Note that the examples in RFC3189 (older version of this document) provides
incorrect SDP "a=fmtp" attribute usage.</t>
<t>In the DV video payload format, the a=fmtp line will be used to show
the encoding type within the DV video and will be used as below:</t>
<t>
<list style='empty'>
<t>a=fmtp:<payload type> encode=<DV-video encoding></t>
</list>
</t>
<t>The required parameter <DV-video encoding> specifies which type of DV
format is used. The DV format name will be one of the following:</t>
<t>
<list style='empty'>
<t>SD-VCR/525-60<vspace />
SD-VCR/625-50<vspace />
HD-VCR/1125-60<vspace />
HD-VCR/1250-50<vspace />
SDL-VCR/525-60<vspace />
SDL-VCR/625-50<vspace />
314M-25/525-60<vspace />
314M-25/625-50<vspace />
314M-50/525-60<vspace />
314M-50/625-50<vspace />
370M/1080-60i<vspace />
370M/1080-50i<vspace />
370M/720-60p<vspace />
370M/720-50p<vspace />
306M/525-60 (for backward compatibility)<vspace />
306M/625-50 (for backward compatibility)</t>
</list>
</t>
<t>In order to show whether the audio data is bundled into the DV stream
or not, a format specific parameter is defined as below:</t>
<t>
<list style='empty'>
<t>a=fmtp:<payload type> encode=<DV-video encoding> audio=<audio bundled></t>
</list>
</t>
<t>The optional parameter <audio bundled> will be one of the following:</t>
<t>
<list style='empty'>
<t>bundled<vspace />
none (default)</t>
</list>
</t>
<t>If the fmtp audio parameter is not present, then audio data MUST NOT
be bundled into the DV video stream.</t>
</section>
<section title="Usage with the SDP Offer/Answer Model">
<t>The following considerations apply when using SDP offer-answer
procedures <xref target="RFC3264"/> to negotiate the use of DV payload in RTP:</t>
<t>
<list style='symbols'>
<t>The "encode" parameter can be used for sendrecv,
sendonly and recvonly streams. Each encode type
MUST use a separate payload type number.</t>
<t>Any unknown parameter in an offer MUST be ignored by the receiver
and MUST NOT be included in the answer.</t>
</list>
</t>
<t>In an offer for unbundled streams, in order to associate the
related audio and video, the group attribute as defined in the
Session Description Protocol (SDP) Grouping Framework
<xref target="RFC5888"/> can be used.</t>
</section>
</section>
<section title="Examples">
<t>Some example SDP session descriptions utilizing DV encoding formats
follow.</t>
<section title="Example for Unbundled Streams">
<t>When using unbundled mode, the RTP streams for video and audio will
be sent separately to different ports or different multicast groups.
When this is done, SDP carries several m=?? lines, one for each media
type of the session (see RFC 4566).</t>
<figure>
<preamble>An example SDP description using these attributes is:</preamble>
<artwork><![CDATA[
v=0
o=ikob 2890844526 2890842807 IN IP4 192.0.2.1
s=POI Seminar
i=A Seminar on how to make Presentations on the Internet
u=http://www.example.net/~ikob/POI/index.html
e=ikob@example.net (Katsushi Kobayashi)
c=IN IP4 233.252.0.1/127
t=2873397496 2873404696
m=audio 49170 RTP/AVP 112
a=rtpmap:112 L16/32000/2
m=video 50000 RTP/AVP 113
a=rtpmap:113 DV/90000
a=fmtp:113 encode=SD-VCR/525-60; audio=none
]]></artwork>
<postamble>
This describes a session where audio and video streams are sent
separately. The session is sent to a multicast group 233.252.0.1.
The audio is sent using L16 format, and the video is sent using SD-VCR 525/60 format which corresponds to NTSC format in consumer DV.
</postamble>
</figure>
</section>
<section title="Example for Bundled Streams">
<t>When sending a bundled stream, all the DIF blocks including system
data will be sent through a single RTP stream.</t>
<figure>
<preamble>An example SDP description for a bundled DV stream is:</preamble>
<artwork><![CDATA[
v=0
o=ikob 2890844526 2890842807 IN IP4 192.0.2.1
s=POI Seminar
i=A Seminar on how to make Presentations on the Internet
u=http://www.example.net/~ikob/POI/index.html
e=ikob@example.net (Katsushi Kobayashi)
c=IN IP4 233.252.0.1/127
t=2873397496 2873404696
m=video 49170 RTP/AVP 112 113
a=rtpmap:112 DV/90000
a=fmtp: 112 encode=SD-VCR/525-60; audio=bundled
a=fmtp: 113 encode=314M-50/525-60; audio=bundled
]]></artwork>
<postamble>
This SDP record describes a session where audio and video streams are
sent bundled. The session is sent to a multicast group 233.252.0.1.
The video is sent using both 525/60 consumer DV and SMPTE standard
314M 50Mbps formats, when the payload type is 112 and 113,
respectively.
</postamble>
</figure>
</section>
</section>
</section>
<section title="Security Considerations" anchor="sec_cons">
<t>RTP packets using the payload format defined in this specification
are subject to the security considerations discussed in the RTP
specification <xref target="RFC3550"/>, and any appropriate RTP profile.
This implies that confidentiality of the media streams is achieved by
encryption. Because the data compression used with this payload format
is applied to end-to-end, encryption may be performed after compression
so there is no conflict between the two operations.</t>
<t>A potential denial-of-service threat exists for data encodings using
compression techniques that have non-uniform receiver-end
computational load. The attacker can inject pathological datagrams
into the stream which are complex to decode and cause the receiver to
be overloaded. However, this encoding does not exhibit any
significant non-uniformity.</t>
<t>As with any IP-based protocol, in some circumstances a receiver may
be overloaded simply by the receipt of too many packets, either
desired or undesired. Network-layer authentication may be used to
discard packets from undesired sources, but the processing cost of
the authentication itself may be too high. In a multicast
environment, mechanisms for joining and pruning of specific sources are
specified in IGMPv3, MLDv2 <xref target="RFC3376"/><xref target="RFC3810"/> or LW-IGMPv3, LW-MLDv2 <xref target="RFC5790"/> and in multicast routing
protocols to allow a receiver to select which sources are allowed to
reach it <xref target="RFC4607"/>.</t>
</section>
<section title="Congestion Control">
<t>The general congestion control considerations for transporting RTP
data apply; see RTP <xref target="RFC3550"/> and any applicable RTP profile like AVP
<xref target="RFC3551"/>.</t>
</section>
<section title="IANA Considerations">
<t>This document updates RFC3189 (older version of this document), and
some registration forms are just updated by this document.
The registration forms (based on the RFC 4855 <xref target="RFC4855"/> definition)
for the Media Types for both video and audio are shown in <xref target="reg_form"/>.</t>
</section>
<section title="Major Changes from RFC 3189">
<t>The changes from RFC 3189 are:</t>
<t>
<list style='format %d.'>
<t>Removed SMPTE 306M, since it is covered by SMPTE 314M format.</t>
<t>Added SMPTE 370M 100Mbps HDTV (1080/60i, 1080/50i, 720/60p, and
720/50p) format.</t>
<t>Incorporated Source Specific Multicast (SSM) spec. for avoiding
overloaded traffic source in multicast usage. Added a reference to
the Source Specific Multicast (SSM) specifications as a way to
reduce unwanted traffic in a multicast application.</t>
<t>Clarified the case where the sender omits subcode DIF block data
from the stream.</t>
<t>Added considerations for the offer/answer model.</t>
<t>Revised Media Types registration form based on new registration
rule (RFC 4855).</t>
<t>Revised section structure based on new example.</t>
</list>
</t>
</section>
<section title="Interoperability with Previous Implementations">
<t>In this section, we discuss interoperability with implementations
based on RFC 3189, which is obsoleted by this document.</t>
<t>RFC 3189 regards SMPTE306M <xref target="SMPTE306M"/> and
SMPTE314M as different encoding formats, although the format
of SMPTE 306M is already covered by SMPTE 314M. Therefore,
this document recommends that the definition depending on
SMPTE306M SHOULD NOT be used, and SMPTE314M SHOULD be used instead.
An RTP application could handle a stream identified in SMPTE306M
encoding as in SMPTE314M encoding instead.</t>
<t>An offer MAY include SMPTE306M encoding coming from a legacy
system and receivers SHOULD support this value.</t>
<t>If an initial offer that did not include SMPTE306M was rejected,
the offerer MAY try a new offer with SMPTE306M. For this case,
an RTP application MAY handle a stream identified in SMPTE306M
encoding as in SMPTE314M encoding instead.</t>
</section>
</middle>
<!-- *****BACK MATTER ***** -->
<back>
<!-- References split into informative and normative -->
<!-- There are 2 ways to insert reference entries from the citation libraries:
1. define an ENTITY at the top, and use "ampersand character"RFC2629; here (as shown)
2. simply use a PI "less than character"?rfc include="reference.RFC.2119.xml"?> here
(for I-Ds: include="reference.I-D.narten-iana-considerations-rfc2434bis.xml")
Both are cited textually in the same manner: by using xref elements.
If you use the PI option, xml2rfc will, by default, try to find included files in the same
directory as the including file. You can also define the XML_LIBRARY environment variable
with a value containing a set of directories to search. These can be either in the local
filing system or remote ones accessed by http (http://domain/dir/... ).-->
<references title="Normative References">
&RFC3550;
&RFC3551;
&RFC2119;
&RFC3190;
&RFC3264;
&RFC4288;
&RFC4566;
&RFC4855;
&RFC5888;
<reference anchor="IEC61834">
<!-- the following is the minimum to make xml2rfc happy -->
<front>
<title>
IEC 61834, Helical-scan digital video cassette recording system
using 6,35 mm magnetic tape for consumer use (525-60, 625-50,
1125-60 and 1250-50 systems)
</title>
<author>
<organization>IEC</organization>
</author>
</front>
</reference>
<reference anchor="SMPTE306M">
<front>
<title>
SMPTE 306M, 6.35-mm type D-7 component format - video
compression at 25Mb/s -525/60 and 625/50.
</title>
<author>
<organization>SMPTE</organization>
</author>
</front>
</reference>
<reference anchor="SMPTE314M">
<front>
<title>
SMPTE 314M, Data structure for DV-based audio and compressed
video 25 and 50Mb/s.
</title>
<author>
<organization>SMPTE</organization>
</author>
</front>
</reference>
<reference anchor="SMPTE370M">
<front>
<title>
SMPTE 370M, Data Structure for DV-Based Audio, Data and
Compressed Video at 100 Mb/s 1080/60i, 1080/50i, 720/60p,
and 720/50p.
</title>
<author>
<organization>SMPTE</organization>
</author>
</front>
</reference>
</references>
<references title="Informative References">
<!-- Here we use entities that we defined at the beginning. -->
&RFC2250;
&RFC3376;
&RFC3810;
&RFC4607;
&RFC5790;
<reference anchor="ISO/IEC11172">
<front>
<title>
ISO/IEC 11172, Coding of moving pictures and associated audio
for digital storage media up to about 1,5 Mbits/s.
</title>
<author>
<organization>ISO/IEC</organization>
</author>
</front>
</reference>
<reference anchor="IEC61883">
<front>
<title>
IEC 61883, Consumer audio/video equipment - Digital interface.
</title>
<author>
<organization>IEC</organization>
</author>
</front>
</reference>
<reference anchor="IEEE1394">
<front>
<title>
IEEE Std 1394-1995, Standard for a High Performance Serial Bus
</title>
<author>
<organization>IEEE</organization>
</author>
</front>
</reference>
<reference anchor="ISO/IEC13818">
<front>
<title>
ISO/IEC 13818, Generic coding of moving pictures and associated
audio information.
</title>
<author>
<organization>ISO/IEC</organization>
</author>
</front>
</reference>
</references>
</back>
</rfc>
| PAFTECH AB 2003-2026 | 2026-04-24 04:23:28 |