One document matched: draft-greevenbosch-mmusic-signal-3d-format-00.txt
mmusic B. Greevenbosch
Internet-Draft Y. Hui
Intended status: Standards Track Huawei
Expires: September 4, 2011 March 3, 2011
Signal 3D format
draft-greevenbosch-mmusic-signal-3d-format-00
Abstract
This document introduces the SDP attribute "3dFormat", which provides
format description of stereoscopic 3D video. In addition, the
grouping mechanism for SDP is extended to cater for stereoscopic 3D
video.
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Note
Discussion and suggestions for improvement are requested, and should
be sent to mmusic@ietf.org.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
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This Internet-Draft will expire on September 4, 2011.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Requirements notation . . . . . . . . . . . . . . . . . . . . 5
3. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. The "3dFormat" attribute . . . . . . . . . . . . . . . . . . . 8
5. Grouping . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
6. Combinations of attribute values and group usage . . . . . . . 12
7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.1. One single frame compatible stream . . . . . . . . . . . . 14
7.2. Two separate streams . . . . . . . . . . . . . . . . . . . 14
7.3. C-stream and depth map stream . . . . . . . . . . . . . . 14
7.4. Stereoscopic 3D video with two different formats . . . . . 15
8. Formal ABNF grammar of the "3dFormat" attribute . . . . . . . 17
9. Security Considerations . . . . . . . . . . . . . . . . . . . 18
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
10.1. "3dFormat" attribute . . . . . . . . . . . . . . . . . . . 19
10.2. "3DS" value for "group" semantics . . . . . . . . . . . . 20
11. Normative References . . . . . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22
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1. Introduction
In stereoscopic 3D multimedia applications, two views are displayed,
one for the left eye and one for the right eye.
There are various ways of formatting the views of Stereoscopic 3D
video. Examples of 3D formats are frame packing (see [HDMIv1.4a])
and the combination of 2D video and auxiliary data such as depth maps
(see [ISO/IEC 23002-3]). Stereoscopic 3D video may be carried over a
single stream or over several streams, depending on its 3D format.
In multimedia streaming applications, the Session Description
Protocol (SDP) [RFC4566] can be used to provide to the receiver
sufficient information about the media streams, and to enable the
receiver to join and participate in the session.
This document defines an extension to SDP that provides sufficient
information about the format of stereoscopic 3D video carried in the
media stream(s). Before accessing the stream(s), the receiver can
use the 3D format description from SDP to determine whether it has
the capability to receive and render the stereoscopic 3D video
content, and whether it can participate in the session.
The mentioned SDP extension is a new SDP attribute "3dFormat", which
provides the format description of stereoscopic 3D video. The design
of the attribute is based on the following requirements, which are
listed only for informational purposes:
o It SHALL be possible to signal that the left and right views are
carried in a single stream, by the use of frame packing.
o It SHALL be possible to signal that 2D video and auxiliary video
(such as depth maps) are carried in a single stream.
o It SHALL be possible to signal that the left and right views are
carried in two separate streams.
o It SHALL be possible to signal that 2D video and auxiliary video
(such as depth maps) are carried in separate streams.
To bind multiple video streams that carry a single stereoscopic 3D
video, this document also extends the SDP grouping mechanism from
[RFC5888].
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2. Requirements notation
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 [RFC2119].
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3. Definitions
2D video
Video that does not in itself contain depth or parallax
information.
auxiliary video
A sequence of depth or parallax maps, which are used to add depth
to 2D video.
C-view
The centre view: a visual entity as seen from a viewpoint between
the left and right eyes. The C-view can be used to calculate the
L- and R-views.
C-stream
A 2D video stream consisting of a sequence of C-views.
depth map
A two dimensional map, each pixel of which defines the depth of
one or more pixels in an associated 2D video frame.
depth map stream
An auxiliary stream, which contains a sequence of depth maps. The
depth map stream is synchronised with the associated 2D video
stream.
frame packing
A format that packs the L- and R-views into a single 2D video
stream. The packing may be done spatially, where each video frame
is divided into sub-frames, one containing the L-view and one
containing the R-view. The packing can also be done sequentially,
where alternating video frames represent L- and R-views.
L-view
A visual entity that is to be projected to the left eye.
L-stream
A 2D video stream consisting of a sequence of L-views.
parallax map
A two dimensional map, each pixel of which defines the parallax of
one or more pixels in an associated 2D video frame.
parallax map stream
An auxiliary stream, which contains a sequence of parallax maps.
The parallax map stream is synchronised with the associated 2D
video stream.
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R-view
A visual entity that is to be projected to the right eye.
R-stream
A 2D video stream consisting of a sequence of R-views.
stereoscopic 3D video
The L- and R-streams, ready to be projected to the viewer's left
and right eyes.
sub-frame
A part of a video frame.
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4. The "3dFormat" attribute
The media-level SDP attribute "3dFormat" signals the format of
stereoscopic 3D video. The attribute transfers this information
through two parameters: one indicating the format type of the
stereoscopic 3D video carried in the media stream(s), and the other
indicating the type of the video component, which is a constituent
element of the stereoscopic 3D video. The video component type
depends on the format type of the stereoscopic 3D video. The syntax
of the attribute is defined as follows:
a=3dFormat:<Format Type> <Component Type>
The <Format Type> can have the following values (as indicated between
the quotes):
"FP" Frame Packing
The L- and R-views are packed into a single stream. The packing
may use a side-by-side, top-and-bottom, interleaved, checkerboard
or frame sequential format.
"SC" Simulcast
The L- and R-streams are transmitted separately.
"2DA" 2D + auxiliary
2D video and auxiliary data (such as depth maps or parallax maps)
are transmitted. These can be transmitted in a single stream, as
well as in two separate streams.
The <Component Type> can have the following values (as indicated
between the quotes):
"C" Centre view
The associated stream is a C-stream.
"CD" centre view and depth map
The associated stream contains both the C-view and depth map
sequences.
"ChB" Checkerboard
The video frame consists of alternating pixels from the
corresponding L- and R-views, as illustrated by Figure 1.
"CP" Centre view and parallax map
The associated stream contains both the C-view and parallax map
sequences.
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"D" Depth map
The associated stream is a sequence of depth maps.
"L" Left view
The associated stream is the L-stream.
"LD" Left view and depth map
The associated stream contains both the L-view and depth map
sequences.
"LIL" Line Interleaved
Each video frame consists of alternating scan lines from the L-
and R-views.
"LP" Left view and parallax map
The associated stream contains both the L-view and parallax map
sequences.
"P" Parallax map
The associated stream is a sequence of parallax maps.
"R" Right view
The associated stream is the R-stream.
"SbS" Side by Side
Each video frame is divided in two equally sized sub-frames,
spatially positioned side by side of each other. One sub-frame
contains the L-view, whereas the other contains the R-view.
"Seq" Frame sequential
The single video stream consists of alternating frames from the L-
and R-streams.
"TaB" Top and Bottom
Each video frame is divided in two equally sized sub-frames,
spatially positioned above each other. One sub-frame contains the
L-view, whereas the other contains the R-view.
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+-+-+-+-+-+-+
|L|R|L|R|L|R|
+-+-+-+-+-+-+
|R|L|R|L|R|L|
+-+-+-+-+-+-+
|L|R|L|R|L|R|
+-+-+-+-+-+-+
The checkerboard pattern. The transmitted video frame is composed of
pixels from the L- and R-views. Samples from the L-view are
indicated with "L", whereas samples from the R-view are indicated
with "R".
Figure 1
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5. Grouping
When multiple streams carry a single stereoscopic 3D video, (e.g.
C-stream and parallax map, or separately transmitted L- and
R-streams), the grouping mechanism from [RFC5888] MUST be used.
However, to cater for the special requirements of 3D signalling, the
semantics are expanded:
group-attribute = "a=group:" semantics *(SP identification-tag)
semantics = "LS" / "FID" / "3DS" / semantics-extension
semantics-extension = token
The grouping is needed when multiple streams carry a single
stereoscopic 3D video. This is the case when the <format type> is
"SC", or the <format type> is "2DA" and the 2D video and auxiliary
data are transmitted as multiple streams. A group with the "3Ds"
semantics is called a "3DS group".
A 3DS group MUST NOT contain data that is (potentially) inconsistent
with other data in the 3DS group:
o A 3DS group MUST NOT contain both a parallax map stream and a
depth map stream.
o A 3DS group MUST NOT contain more than one parallax map stream.
o A 3DS group MUST NOT contain more than one depth map stream.
o A 3DS group MUST contain at least one 2D video stream.
o If a 3GS group contains an L- and an R-stream, it MUST NOT contain
a depth map or a parallax map.
o If a 3DS group contains only one 2D video stream, it MUST also
contain a parallax map stream or a depth map stream.
o If a 3DS group contains a parallax map stream or a depth map
stream, it MUST also contain a 2D video stream.
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6. Combinations of attribute values and group usage
The following table summarises the possible combinations of attribute
values and grouping:
+-----+----+-------+---------+
| | FP | SC | 2DA |
+-----+----+-------+---------+
| C | | | D/P,3DS |
| | | | |
| CD | | | T |
| | | | |
| ChB | T | | |
| | | | |
| CP | | | T |
| | | | |
| D | | | C/L,3DS |
| | | | |
| L | | R,3DS | D/P,3DS |
| | | | |
| LD | | | T |
| | | | |
| LIL | T | | |
| | | | |
| LP | | | T |
| | | | |
| P | | | C/L,3DS |
| | | | |
| R | | L,3DS | |
| | | | |
| SbS | T | | |
| | | | |
| Seq | T | | |
| | | | |
| TaB | T | | |
+-----+----+-------+---------+
The table is to be read as follows:
o The columns indicate <Format Type> values, whereas the rows
indicate <Component Type> values.
o For one particular column, we denote the <Format Type> value by
"FT" and the <Component Type> value by "CT".
o When an entry in the table is empty, it means that the
corresponding combination of FT and CT is not allowed.
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o When an entry in the table contains a single <Component Type>
value CTsec, it means that another stream with the <Component
Type> value CTsec and the same <Format Type> value FT is needed.
o When multiple <Component Type> values are listed, separated by a
"/" symbol, only one secondary stream is needed, which must have
one of the listed <Component Type> values, and the same <Format
Type> value FT.
o When an entry contains "3DS", it means that a 3DS group is needed.
o When an entry in the table contains the letter "T" (true), it
means that the corresponding combination FT and CT is allowed,
that there is no required secondary stream, and that a 3DS group
is not needed.
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7. Examples
7.1. One single frame compatible stream
The following is an example of an SDP description of a session which
contains a single stream, in which the L- and R-streams are packed,
in side by side fashion.
v=0
o=Alice 2890844526 2890842807 IN IP4 131.163.72.4
s=The technology of 3D-TV
c=IN IP4 131.164.74.2
t=0 0
m=video 49170 RTP/AVP 99
a=rtpmap:99 H264/90000
a=3dFormat:FP SbS
m=audio 52890 RTP/AVP 10
a=rtpmap:10 L16/16000/2
7.2. Two separate streams
The following is an example of an SDP description of a session with
an audio stream, an L-stream and an R-stream.
v=0
o=Alice 2890844526 2890842807 IN IP4 131.163.72.4
s=The technology of 3D-TV
c=IN IP4 131.164.74.2
t=0 0
a=group:3DS 1 2
m=video 49170 RTP/AVP 99
a=rtpmap:99 H264/90000
a=3dFormat:SC L
a=mid:1
m=video 49172 RTP/AVP 101
a=rtpmap:101 H264/90000
a=3dFormat:SC R
a=mid:2
m=audio 52890 RTP/AVP 10
a=rtpmap:10 L16/16000/2
7.3. C-stream and depth map stream
The following is an example of an SDP description of a session with
an audio stream, a C-stream and a depth map stream.
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v=0
o=Alice 2890844526 2890842807 IN IP4 131.163.72.4
s=The technology of 3D-TV
c=IN IP4 131.164.74.2
t=0 0
a=group:3DS 1 2
m=video 49170 RTP/AVP 99
a=rtpmap:99 H264/90000
a=3dFormat:2DA C
a=mid:1
m=video 49172 RTP/AVP 101
a=rtpmap:101 H264/90000
a=3dFormat:2DA D
a=mid:2
m=audio 52890 RTP/AVP 10
a=rtpmap:10 L16/16000/2
7.4. Stereoscopic 3D video with two different formats
In the following example, there are two different formats for
stereoscopic 3D video. One consists of stream 1 (C-stream) and
stream 2 (parallax map stream), whereas the other consists of stream
3 (L-stream) and stream 4 (R-stream). There also is an audio stream,
which can be used with both formats.
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v=0
o=Alice 2890844526 2890842807 IN IP4 131.163.72.4
s=The technology of 3D-TV
c=IN IP4 131.164.74.2
t=0 0
a=group:3DS 1 2
a=group:3DS 3 4
m=video 49170 RTP/AVP 99
a=rtpmap:99 H264/90000
a=3dFormat:2DA C
a=mid:1
m=video 49172 RTP/AVP 101
a=rtpmap:101 H264/90000
a=3dFormat:2DA P
a=mid:2
m=video 49174 RTP/AVP 103
a=rtpmap:103 H264/90000
a=3dFormat:SC L
a=mid:3
m=video 49176 RTP/AVP 105
a=rtpmap:105 H264/90000
a=3dFormat:SC R
a=mid:4
m=audio 52890 RTP/AVP 10
a=rtpmap:10 L16/16000/2
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8. Formal ABNF grammar of the "3dFormat" attribute
This section contains the formal ABNF grammar of the "3dFormat"
attribute.
3dFormat-attribute = "a=3dFormat:" formatType componentType
formatType = "FP"/"SC"/"2DA"
componentType = "C"/"CD"/"ChB"/"CP"/"D"/"L"/"LD"/
"LIL"/"LP"/"P"/"R"/"SbS"/"Seq"/"TaB"
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9. Security Considerations
The authors foresee no security issues in addition to those already
listed in [RFC4566].
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10. IANA Considerations
10.1. "3dFormat" attribute
Following the guidelines in [RFC4566], the SDP attribute has to be
registered at IANA:
o Contact name/email: authors of this RFC
o Attribute name: 3dFormat
o Long-form attribute name: Attribute for signalling the format of a
stereoscopic 3D video carried in the media stream(s).
o Type of attribute: media level
o Subject to charset: no
The "3dFormat" SDP media-level attribute is used to signal the format
of stereoscopic 3D video, carried in one or more media stream(s).
The attribute has the following syntax:
a=3dFormat:<Format Type> <Component Type>
The <Format Type> indicates the format type of the stereoscopic 3D
video carried in the media stream(s). It indicates whether the
stereoscopic 3D video is frame packed, simulcast or consists of a 2D
video stream and an auxiliary stream. The <Format Type> can have the
following values (as indicated between the quotes):
"FP" frame packed
"SC" simulcast
"2DA" 2D + auxiliary
The <Component Type> indicates the type of the video component, which
is a constituent element of the stereoscopic 3D video. It can have
the following values:
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"C" centre view
"CD" centre view and depth map
"ChB" checkerboard
"CP" centre view and parallax map
"D" depth map
"L" left view
"LD" left view and depth map
"LIL" line interleaved
"LP" left view and parallax map
"P" parallax map
"R" right view
"SbS" side by side
"Seq" frame sequential
"TaB" top and bottom
10.2. "3DS" value for "group" semantics
Following the standards action policy from [RFC5226], the following
semantics have to be registered with IANA in the "Semantics for the
"group" SDP Attribute" registry under "SDP Parameters":
+-----------------+-------+-----------+
| Semantics | Token | Reference |
+-----------------+-------+-----------+
| 3D synchronised | 3DS | this RFC |
+-----------------+-------+-----------+
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11. Normative References
[HDMIv1.4a]
HDMI, "HDMI Specification Version 1.4a", ISO/IEC
FDIS 23002-3:2007(E), March 2010.
[ISO/IEC 23002-3]
MPEG, "MPEG video technologies part 3: Representation of
auxiliary video and supplemental information", ISO/IEC
FDIS 23002-3:2007(E), December 2002.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, July 2006.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC5888] Camarillo, G. and H. Schulzrinne, "The Session Description
Protocol (SDP) Grouping Framework", RFC 5888, June 2010.
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Authors' Addresses
Bert Greevenbosch
Huawei Technologies Co., Ltd.
Huawei Industrial Base
Bantian, Longgang District
Shenzhen 518129
P.R. China
Phone: +86-755-28978088
Email: bgreeven@huawei.com
Hui Yu
Huawei Technologies Co., Ltd.
Huawei Nanjing R&D Center
101 Software Avenue
Yuhuatai District
Nanjing 210012
P.R. China
Phone: +86-25-56620323
Email: huiyu@huawei.com
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