RTP Payload Format for sub-codestream latency JPEG 2000 streaming
draft-ietf-avtcore-rtp-j2k-scl-00
| Document | Type | Active Internet-Draft (avtcore WG) | |
|---|---|---|---|
| Authors | Pierre-Anthony Lemieux , David Taubman | ||
| Last updated | 2023-11-17 | ||
| Replaces | draft-lemieux-avtcore-rtp-j2k-scl | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | (None) | ||
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draft-ietf-avtcore-rtp-j2k-scl-00
Audio/Video Transport Core Maintenance P.-A. Lemieux, Ed.
Internet-Draft Sandflow Consulting LLC
Intended status: Standards Track D. S. Taubman
Expires: 20 May 2024 University of New South Wales
17 November 2023
RTP Payload Format for sub-codestream latency JPEG 2000 streaming
draft-ietf-avtcore-rtp-j2k-scl-00
Abstract
This RTP payload format defines the streaming of a video signal
encoded as a sequence of JPEG 2000 codestreams. The format allows
sub-codestream latency, such that the first RTP packet for a given
codestream can be emitted before the entire codestream is available.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 20 May 2024.
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
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extracted from this document must include Revised BSD License text as
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provided without warranty as described in the Revised BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 4
3. Media format description . . . . . . . . . . . . . . . . . . 4
4. Video signal description . . . . . . . . . . . . . . . . . . 5
5. Payload Format . . . . . . . . . . . . . . . . . . . . . . . 6
5.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 6
5.2. RTP Fixed Header Usage . . . . . . . . . . . . . . . . . 7
5.3. Main Packet Payload Header . . . . . . . . . . . . . . . 8
5.4. Body Packet Payload Header . . . . . . . . . . . . . . . 13
6. JPEG 2000 codestream requirements . . . . . . . . . . . . . . 15
6.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 15
6.2. Transmitting multi-tile images as multiple single-tile
images . . . . . . . . . . . . . . . . . . . . . . . . . 15
7. Sender requirements . . . . . . . . . . . . . . . . . . . . . 16
7.1. Main Packet . . . . . . . . . . . . . . . . . . . . . . . 16
7.2. RTP Packet filtering . . . . . . . . . . . . . . . . . . 16
7.3. Resync point . . . . . . . . . . . . . . . . . . . . . . 16
7.4. PTSTAMP field . . . . . . . . . . . . . . . . . . . . . . 17
7.5. RES field . . . . . . . . . . . . . . . . . . . . . . . . 17
7.6. Extra information . . . . . . . . . . . . . . . . . . . . 17
7.7. Reserved values . . . . . . . . . . . . . . . . . . . . . 17
7.8. Extension values . . . . . . . . . . . . . . . . . . . . 17
7.9. Code-block caching . . . . . . . . . . . . . . . . . . . 18
8. Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . 18
8.1. PTSTAMP . . . . . . . . . . . . . . . . . . . . . . . . . 18
8.2. QUAL . . . . . . . . . . . . . . . . . . . . . . . . . . 18
8.3. RES . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8.4. Extra information . . . . . . . . . . . . . . . . . . . . 21
8.5. Reserved values . . . . . . . . . . . . . . . . . . . . . 22
8.6. Extension values . . . . . . . . . . . . . . . . . . . . 22
8.7. Code-block caching . . . . . . . . . . . . . . . . . . . 22
9. Media Type . . . . . . . . . . . . . . . . . . . . . . . . . 22
9.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 22
9.2. Definition . . . . . . . . . . . . . . . . . . . . . . . 23
10. Mapping to the Session Description Protocol (SDP) . . . . . . 29
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29
12. Security considerations . . . . . . . . . . . . . . . . . . . 30
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 30
13.1. Normative References . . . . . . . . . . . . . . . . . . 30
13.2. Informative References . . . . . . . . . . . . . . . . . 31
Appendix A. Pixel formats . . . . . . . . . . . . . . . . . . . 32
Appendix B. Signal formats . . . . . . . . . . . . . . . . . . . 34
Appendix C. Sample formats . . . . . . . . . . . . . . . . . . . 34
Appendix D. Summary of Changes (Informative) . . . . . . . . . . 35
D.1. Introduction . . . . . . . . . . . . . . . . . . . . . . 35
D.2. Changes from draft-ietf-avtcore-rtp-j2k-scl-00 . . . . . 35
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Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 35
1. Introduction
This RTP payload format specifies the streaming of a video signal
encoded as a sequence of JPEG 2000 codestreams.
In addition to supporting a variety of frame scanning techniques
(progressive, interlaced and progressive segmented frame) and image
characteristics, the payload format includes the following features
specifically designed for streaming applications:
* the payload format allows sub-codestream latency such that the
first RTP packet of a given codestream to be emitted before the
entire codestream is available. Specifically, the payload format
does not rely on the JPEG 2000 PLM and PLT marker segments for
recovery after RTP Packet loss since these markers can only be
written after the codestream is complete and are thus incompatible
with sub-codestream latency. Instead, the payload format includes
payload header fields (ORDH, ORDB, POS and PID) that indicates
whether the RTP packet contains a resynchronization (resync) point
and how a recipient can restart codestream processing from that
resync point. This contrasts with [RFC5371], which also specifies
an RTP payload format for JPEG 2000, but relies on codestream
structures that cannot be emitted until the entire codestream is
available.
* as in [RFC4175], the payload header contains an extension (ESEQ)
to the standard 16-bit RTP sequence number, enabling the payload
format to accommodate high data rates without ambiguity. This is
necessary as the standard sequence number will roll over very
quickly for high data rates likely to be encountered in this
application. For example, the standard sequence number will roll
over in 0.5 seconds with a 1-Gbps video stream with RTP Packet
sizes of at least 1000 octets, which can be a problem for
detecting loss and out-of-order packets particularly in instances
where the round-trip time is greater than the roll over period
(0.5 seconds in this example).
* the payload header optionally contains a temporal offset (PTSTAMP)
relative to the first RTP Packet with the same value of RTP
timestamp field (Section 5.2). The higher resolution of PTSTAMP
compared to the timestamp allows receivers to recover the sender's
clock more rapidly.
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Finally, the payload format also makes use of the unique scalability
features of JPEG 2000 to allow a network agent or recipient to
discard resolutions and/or quality layers merely by inspecting
payload headers (QUAL and RES fields), without having to parse the
underlying codestream.
2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Media format description
The following summarizes the structure of the JPEG 2000 codestream,
which is specified in detail at [jpeg2000-1].
NOTE: as described at Section 6, a JPEG 2000 codestream allows
capabilities defined in any part of the JPEG 2000 family of
standards, including those specified in [jpeg2000-2] and
[jpeg2000-15].
JPEG 2000 represents an image as one or more components, e.g., R, G
and B, each uniformly sampled on a common rectangular reference grid.
An image can be further divided into contiguous rectangular tiles
that are each independently coded and decoded.
NOTE: This payload format allows the transmission of multi-tile
images as multiple single-tile images per stream, as specified at
Section 6.2.
JPEG 2000 codes each image as a standalone codestream. Each
codestream consists of (i) marker segments, which contain coding
parameters and metadata, and (ii) coded data.
The codestream starts with an SOC marker segment and ends with an EOC
marker segment. The main header of the codestream consists of marker
segments between the SOC and first SOT marker segment and contains
information that applies to the codestream in its entirety. It is
generally impossible to decode a codestream without its main header.
The rest of the codestream consists of additional marker segments
(tile-part headers) interleaved with coded image data.
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The coded image data ultimately consists of code-blocks, each
containing coded samples belonging to a rectangular (spatial) region
within one resolution level of one component. Code-blocks are
further collected into precincts, which, accordingly, represents
code-blocks belonging to a spatial region within one resolution level
of one component.
The image coded data can be arranged into several progression orders,
which dictates which aspect of the image appears first in the
codestream (in terms of byte offset). The progression orders are
parameterized according to:
Position (P) The first lines of the image come before the last lines
of the image.
Component (C) The first component of the image come before the last
component of the image.
Resolution Layer (R) The information needed to reconstruct the lower
spatial resolutions of the image come before the information
needed to reconstruct the higher spatial resolutions of the image.
Quality Layer (L) The information needed to reconstruct the most-
significant bits of each sample come before the information needed
to reconstruct the least-significant bit of each sample.
For example, in the PRCL progression order, the information needed to
reconstruct the first lines of the image come before that needed to
reconstruct the last lines of the image and, within a collection of
lines, the information needed to reconstruct the lower spatial
resolutions of the image come before the information needed to
reconstruct the higher spatial resolutions. This progression order
is particular useful for sub-frame latency operations.
4. Video signal description
This RTP payload format supports three distinct video frame scanning
techniques:
* Progressive frame
* Interlaced frame, where each frame consists of two fields. Field
1 occurs temporarily before Field 2. The height in lines of each
field is half the height of the image.
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* Progressive segmented frame (PsF), where each frame consists of
two segments. Segment 1 contains the odd lines (1, 3, 5, 7,...)
of a frame and Segment 2 contains the even lines (2, 4, 6, 8,...)
of the same frame, where lines from the top of the frame to the
bottom of the frame are numbered sequentially starting at 1.
All frames are scanned left to right, top to bottom.
5. Payload Format
5.1. General
<----------- Codestream (image) --------->
| |
< Extended Header > |
| | |
+-----+-----+-----+------------//--+-----+-----+---------
| SOC | ... | SOD | .............. | EOC | P | SOC ...
+-----+-----+-----+------------//--+-----+-----+---------
| |
| |
| |
+---------------------+------+-//--+-----------+---------
Packets | Main | Body | ... | Body | Main ...
+---------------------+------+-//--+-----------+---------
Figure 1: Packetization of a sequence of JPEG 2000 codestreams
(not to scale). P are arbitrary padding bytes.
Each RTP packet, as specified at [RFC3550], is either a Main Packet
or a Body Packet.
A Main Packet consists of the following ordered sequence of
structures concatenated without gaps:
* the RTP Fixed Header;
* a Main Packet Payload Header, as specified at Section 5.3; and
* the payload, which consists of a JPEG 2000 codestream fragment.
A Body Packet consists of the following ordered sequence of
structures concatenated without gaps:
* the RTP Fixed Header;
* a Body Packet Payload Header, as specified at Section 5.4; and
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* the payload, which consists of a JPEG 2000 codestream fragment.
When concatenated, the sequence of JPEG 2000 codestream fragments
emitted by the sender MUST be a sequence of JPEG 2000 codestreams
where two successive JPEG 2000 codestreams MAY be separated by one or
more arbitrary padding bytes.
The JPEG 2000 codestreams MUST conform to Section 6.
The padding bytes MUST be ignored by the recipient.
NOTE: Padding bytes can be used to achieve constant bit rate
transmission.
A JPEG 2000 codestream consists of the bytes between, and including,
the SOC and EOC markers, as defined in [jpeg2000-1].
A JPEG 2000 codestream fragment does not necessarily contain complete
JPEG 2000 packets, as defined in [jpeg2000-1].
A JPEG 2000 codestream Extended Header consists of the bytes between,
and including, the SOC marker and the first SOD marker.
The payload of a Body Packet MUST NOT contain any bytes of the JPEG
2000 codestream Extended Header.
The payload of a Main Packet MUST contain at least one byte of the
JPEG 2000 codestream Extended Header and MAY contain bytes other than
those of the JPEG 2000 codestream Extended Header.
A payload MUST NOT contain bytes from more than one JPEG 2000
codestream.
5.2. RTP Fixed Header Usage
The following RTP header fields have a specific meaning in the
context of this payload format:
marker
1 The payload contains an EOC marker.
0 Otherwise
timestamp
The timestamp is the presentation time of the image to which the
payload belongs.
The timestamp clock rate is 90 kHz.
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The timestamp of successive progressive frames MUST advance at
regular increments based on the instantaneous video frame rate.
The timestamp of Field 1 of successive interlaced frames MUST
advance at regular increments based on the instantaneous video
frame rate, and the Timestamp of Field 2 MUST be offset from the
timestamp of Field 1 by one half of the instantaneous frame
period.
The timestamp of both segments of a progressive segmented frame
MUST be equal.
timestamp of all RTP packets of a given image MUST be equal.
sequence number
The low-order bits of the RTP sequence number. The higher order
bits of the RTP sequence number are contained in the ESEQ field.
5.3. Main Packet Payload Header
Figure 1 specifies the structure of the payload header. Fields are
interpreted as unsigned binary integers in network order.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|MH | TP |ORDH |P|XTRAC| PTSTAMP | ESEQ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R|S|C| RSVD |*| PRIMS | TRANS | MAT |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| XTRAB |
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* RANGE
Figure 2: Structure of the Main Packet Payload Header
MH
0
The RTP Packet is a Body Packet.
1
The RTP Packet is a Main Packet and the codestream has more
than one Main Packet. The next RTP Packet is a Main Packet.
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2
The RTP Packet is a Main Packet and the codestream has more
than one Main Packet. The next RTP Packet is a Body Packet.
3
The RTP Packet is a Main Packet and the codestream has exactly
one Main Packet.
TP
Indicates the scanning structure of the image to which the payload
belongs.
0
Progressive frame.
1
Field 1 of an interlaced frame, where the first line of the
field is the first line of the frame.
2
Field 2 of an interlaced frame, where the first line of the
field is the second line of the frame.
3
Field 1 of an interlaced frame, where the first line of the
field is the second line of the frame.
4
Field 2 of an interlaced frame, where the first line of the
field is the first line of the frame.
5
Segment 1 of a progressive segmented frame, where the first
line of the image is the first line of the frame.
6
Segment 2 of a progressive segmented frame, where the first
line of the image is the second line of the frame.
7
Extension value. See Section 8.6 and Section 7.8.
ORDH
Specifies the progression order used by the codestream and whether
resync points are signaled.
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0
Resync points are not necessarily signaled. The progression
order can vary over the codestream.
1
The progression order is LRCP for the entire codestream. The
first resync point is specified in every Body Packet that
contains one or more resync points.
2
The progression order is RLCP for the entire codestream. The
first resync point is specified in every Body Packet that
contains one or more resync points.
3
The progression order is RPCL for the entire codestream. The
first resync point is specified in every Body Packet that
contains one or more resync points.
4
The progression order is PCRL for the entire codestream. The
first resync point is specified in every Body Packet that
contains one or more resync points.
5
The progression order is CPRL for the entire codestream. The
first resync point is specified in every Body Packet that
contains one or more resync points.
6
The progression order is PRCL for the entire codestream. The
first resync point is specified in every Body Packet that
contains one or more resync points.
7
The progression order can vary over the codestream. The first
resync point is specified in every Body Packet that contains
one or more resync points.
ORDH MUST be 0 is the codestream consists of more than one tile.
NOTE: Only ORDH = 4 and ORDH = 6 allow sub-codestream latency
streaming.
NOTE: Progression order PRCL is defined in [jpeg2000-2]. The
other progression orders are specified in [jpeg2000-1].
P
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0
PTSTAMP is not used.
1
PTSTAMP is used.
XTRAC
Length, in multiples of 4 bytes, of the XTRAB field.
PTSTAMP
PTSTAMP = (timestamp + TOFF) mod 4096, if P = 1 in the Main Packet
of this codestream.
TOFF is the transmission time of this RTP Packet, in the timebase
of the timestamp clock and relative to the first packet with the
same timestamp value.
TOFF = 0 in the first RTP Packet with the same timestamp value.
PTSTAMP = 0, if P = 0 in the Main Packet of this codestream.
NOTE: As described at Section 7.4 and Section 8.1, PTSTAMP is
intended to improve clock recovery at the receiver and only
applies when the transmission time of two consecutive RTP packets
with identical timestamp fields differ by no more than 45 ms =
4095/90,000. [RFC5450] provides addresses the general case when a
RTP packet is transmitted at a time other than its nominal
transmission time.
ESEQ
The high order bits of the extended sequence number.
R
Determines whether Main Packet and codestream header information
can be reused across codestreams.
1
All Main Packets in this stream, as identified by its SSRC
value:
* MUST have identical Main Packet Payload Headers, with the
exception of their TP, MH, ESEQ and PTSTAMP fields;
* MUST contain the same codestream main header information,
with the exception of the SOT and COM marker segments, and
any pointer marker segments; and
* MUST NOT contain bytes other than Extended Header bytes.
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0
Otherwise
S
0
Component colorimetry is not specified, and left to the session
or the application.
PRIMS, TRANS and MAT and RANGE MUST be zero.
1
Component colorimetry is specified by the PRIMS, TRANS and MAT
and RANGE fields.
The codestream components MUST conform to one of the
combinations at Table 1.
+===================================+====================+
| Combination name | Component index |
| +====+=====+=====+===+
| | 0 | 1 | 2 | 3 |
+===================================+====+=====+=====+===+
| Y | Y | | | |
+===================================+----+-----+-----+---+
| YA | Y | A | | |
+===================================+----+-----+-----+---+
| RGB | R | G | B | |
+===================================+----+-----+-----+---+
| RGBA | R | G | B | A |
+===================================+----+-----+-----+---+
| YCbCr | Y | C_B | C_R | |
+===================================+----+-----+-----+---+
| YCbCrA | Y | C_B | C_R | A |
+===================================+----+-----+-----+---+
| The channel A is an opacity channel. The minimum |
| sample value (0) indicates a completely transparent |
| sample, and the maximum sample value (as determined by |
| the bit depth of the codestream component) indicates a |
| completely opaque sample. The opacity channel MUST |
| map to a component with unsigned samples. |
+--------------------------------------------------------+
Table 1: Mapping of codestream components to color
channels
C
0
Code-block caching is not in use.
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1
Code-block caching is in use.
R MUST be equal to 1.
RSVD
Reserved value. See Section 8.5 and Section 7.7.
RANGE
Value of the VideoFullRangeFlag specified in [rec-itu-t-h273]
PRIMS
One of the ColourPrimaries values specified in [rec-itu-t-h273]
TRANS
One of the TransferCharacteristics values specified in
[rec-itu-t-h273]
MAT
One of the MatrixCoefficients values specified in [rec-itu-t-h273]
XTRAB
Allows the contents of the Main Packet Payload Header to be
extended in the future. See Section 8.4 and Section 7.6.
5.4. Body Packet Payload Header
Figure 3 specifies the structure of the Body Packet Payload Header.
Fields are interpreted as unsigned binary integers in network order.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|MH | TP |RES |*|QUAL | PTSTAMP | ESEQ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| POS | PID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* ORDH
Figure 3: Structure of the Body Packet Payload Header
RES
0
The payload can contribute to all resolution layers.
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Otherwise
The payload contains at least one byte of one JPEG 2000 packet
belonging to resolution level (N_L + RES - 7) but does not
contain any byte of any JPEG 2000 packet belonging to lower
resolution levels. N_L is the number of decomposition levels
of the codestream.
ORDB
0
No resync point is specified for the payload.
1
The payload contains a resync point.
ORDB MUST be 0 is the codestream consists of more than one tile.
QUAL
0
The payload can contribute to all quality layers.
Otherwise
The payload contributes only to quality layer index QUAL or
above.
POS
Byte offset from the start of the payload to the first byte of the
resync point belonging to the precinct identified by PID.
POS MUST be 0 if ORDB = 0.
PID
Unique identifier of the precinct of the resync point.
PID = c + s * num_components
where:
* _c_ is the index (starting from 0) of the image component to
which the precinct belongs;
* _s_ is a sequence number which identifies the precinct within
its tile-component; and
* _num_components_ is the number of components of the codestream.
If PID is present, the payload MUST NOT contain codestream bytes
from more than one precinct.
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PID MUST be 0 if ORDB = 0.
NOTE: PID is identical to precinct identifier I specified in
[jpeg2000-9].
6. JPEG 2000 codestream requirements
6.1. General
The JPEG 2000 codestream MAY include capabilities beyond those
specified at [jpeg2000-1], including those specified in [jpeg2000-2]
and [jpeg2000-15].
NOTE: The Rsiz parameter and CAP marker segments of each JPEG 2000
codestream contain detailed information on the capabilities necessary
to decode the codestream.
NOTE: The caps media type parameter defined in Section 9.2 allows
applications to signal required device capabilities.
NOTE: The block coder specified at [jpeg2000-15] improves throughput
and reduces latency compared to the original arithmetic block coder
defined in [jpeg2000-1].
For interlaced or progressive segmented frames, the height specified
in the JPEG 2000 main header MUST be the height in lines of the field
or the segment, respectively.
If any decomposition level involves only horizontal decomposition
then no decomposition level MUST involve only vertical decomposition;
and conversely, if any decomposition level involves only vertical
decomposition then no decomposition level MUST involve only
horizontal decomposition.
6.2. Transmitting multi-tile images as multiple single-tile images
A sequence of multi-tile images can be transmitted by splitting it
into multiple sequences of single-tile images, where:
* each sequence of single-tile images corresponds to a unique tile
of the multi-tile image;
* each sequence of single-tile images is transmitted in a separate
RTP stream;
* the coordinates of each single-tile image are expressed using the
coordinate system of the multi-tile image; and
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* the bitstreams of each of each single-tile image are identical to
the corresponding bitstreams in the multi-tile image.
Such sequences of single-tile images are identified using the tile
media type parameter specified at Section 9.2.
7. Sender requirements
7.1. Main Packet
Only Main Packets MAY contain bytes of the JPEG 2000 codestream
Extended Header.
The sender MUST either emit a single Main Packet with MH = 3, or one
or more Main Packets with MH = 1 followed by a single Main Packet
with MH = 2.
The Main Packet Payload Headers fields MUST be identical in all Main
Packet of a given codestream, with the exception of:
* MH;
* ESEQ; and
* PTSTAMP.
7.2. RTP Packet filtering
A network agent MAY strip out RTP Packet from a codestream that are
of no interest to a particular client, e.g., based on a resolution or
a spatial region of interest. Such a network agent SHOULD include a
CSRC identifier to identify the SSRC field of the original source
from which content was stripped.
7.3. Resync point
A resync point is the first byte of JPEG 2000 packet header data for
a precinct and for which PID < 2^24.
NOTE: Resync points cannot be specified if the codestream consists of
more than one tile (ORDB and ORDH are both equal to zero). To
transmit codestreams that consist of more than one tile and benefit
from resync points, the technique specified at Section 6.2 can be
used.
NOTE: A resync point can be used by a receiver to process a
codestream even if earlier packets in the codestream have been
corrupted, lost or deliberately discarded by a network agent. As a
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corollary, resync points can be used by a network agent to discard
packets that are not relevant to a given rendering resolution or
region of interest. Resync points play a role similar to pointer
marker segments, albeit tailored for high bandwidth low latency
streaming applications.
7.4. PTSTAMP field
A sender SHOULD set P = 1, but only if it can generate PTSTAMP
accurately.
PTSTAMP can be derived from the same clock that is used to produce
the 32-bit timestamp field in the RTP fixed header. Specifically, a
sender maintains, at least conceptually, a 32-bit counter that is
incremented by a 90kHz clock. The counter is sampled at the point
when each RTP Packet is or SHOULD be at least notionally transmitted
and the 12 LSBs of the sample are stored in the PTSTAMP field.
If P = 1, then the transmission time TOFF (as defined at Section 5.3)
for two consecutive RTP packets with identical timestamp fields MUST
NOT differ by more than 4095.
7.5. RES field
A sender SHOULD set RES > 0 whenever possible.
NOTE: While a sender can always safely set RES = 0, this makes it
more difficult to discard packets based on resolution, as described
at Section 8.3.
7.6. Extra information
The sender MUST set the value of XTRAC to 0.
Future edition of this specification can permit other values.
7.7. Reserved values
The sender MUST set reserved values to 0.
Future edition of this specification can specify other values such
that these values can be ignored by receivers that conform to this
specification.
7.8. Extension values
A sender MUST NOT use an extension value.
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7.9. Code-block caching
This section applies only if C = 1.
A sender can improve bandwidth efficiency by only occasionally
transmitting code-blocks corresponding to static portions of the
video and otherwise transmitting empty code-blocks. When C = 1, and
as described at Section 8.7, a receiver maintains a simple cache of
previously received code-blocks, which it uses to replace empty code-
blocks.
A sender alone determines which and when code-blocks are replaced
with empty code-blocks.
The sender cannot however determine with certainty the state of the
receiver's cache: some code-blocks might have been lost in transit,
the sender doesn't know exactly when the receiver started processing
the stream, etc.
A code-block is _empty_ if:
* it does not contribute code-bytes as specified in the parent JPEG
2000 packet header; or
* if the code-block conforms to [jpeg2000-15], contains an HT
cleanup segment and the first two bytes of the Magsgn byte-stream
are between 0xFF80 and 0xFF8F.
NOTE: the last condition allows the encoder to insert padding bytes
to achieve a constant bit rate even when code-block does not
contribute code-bytes, as suggested at [jpeg2000-15], F.4.
8. Receiver
8.1. PTSTAMP
Receivers can use PTSTAMP values to accelerate sender clock recovery
since PTSTAMP typically updates more regularly than timestamp.
8.2. QUAL
A receiver can discard packets where QUAL > N if it is interested in
reconstructing an image that only incorporates quality layers N and
below.
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8.3. RES
The JPEG 2000 coding process decomposes an image using a sequence of
discrete wavelet transforms (DWT) stages.
+===============+============+=============+===========+============+
| Decomposition | Resolution | Subbands | Keep all | ... to |
| level | level | | Body | decode an |
| | | | Packets | image with |
| | | | with RES | at most |
| | | | equal to | these |
| | | | or less | dimensions |
| | | | than | |
| | | | this | |
| | | | value... | |
+===============+============+=============+===========+============+
| 1 | 5 | HL1,LH1,HH1 | 7 | W x H |
+---------------+------------+-------------+-----------+------------+
| 2 | 4 | HL2,LH2,HH2 | 6 | (W/2) x |
| | | | | (H/2) |
+---------------+------------+-------------+-----------+------------+
| 3 | 3 | HL3,LH3,HH3 | 5 | (W/4) x |
| | | | | (H/4) |
+---------------+------------+-------------+-----------+------------+
| 4 | 2 | HL4,LH4,HH4 | 4 | (W/8) x |
| | | | | (H/8) |
+---------------+------------+-------------+-----------+------------+
| 5 | 1 | HL5,LH5,HH5 | 3 | (W/16) x |
| | | | | (H/16) |
+---------------+------------+-------------+-----------+------------+
| 5 | 0 | LL5 | 2 | (W/32) x |
| | | | | (H/32) |
+---------------+------------+-------------+-----------+------------+
Table 2: Optional discarding of Body Packets based on the value
of the RES field when decoding a reduced resolution image, in the
case where N_L = 5 and all DWT stages consist of both horizontal
and vertical transforms. The image has nominal width and height
of W x H.
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Table 2 illustrates the case where each DWT stage consists of both
horizontal and vertical transforms, which is the only mode supported
in [jpeg2000-1]. The first stage transforms the image into (i) the
image at half-resolution (LL1 sub-bands) and (ii) residual high-
frequency data (HH1, LH1, HL1 sub-bands). The second stage
transforms the image at half-resolution (LL1 sub-bands) into the
image at quarter resolution (LL2 sub-bands) and residual high-
frequency data (HH2, LH2, HL2 sub-bands). This process is repeated
N_L times, where N_L is the number of decomposition levels as defined
in the COD and COC marker segments of the codestream.
The decoding process reconstructs the image by reversing the coding
process, starting with the lowest resolution image stored in the
codestream (LL_(N_L)).
As a result, it is possible to reconstruct a lower resolution of the
image by stopping the decoding process at a selected stage. For
example, in order to reconstruct the image at quarter resolution
(LL2), only sub-bands with index greater than 2, e.g., HL3, LH3, HH3,
HL4, LH4, HH4, etc., are necessary. In other words, a receiver that
wishes to reconstruct an image at quarter resolution could discard
all packets where RES >= 6 since those packets can only contribute to
HL1, LH1, HH1, HL2, LH2 and HH2 sub-bands.
In the case where all DWT stages consist of both horizontal and
vertical transforms, the maximum decodable resolution is reduced by a
factor of 2^(7 - N) if all Body Packets where RES > N are discarded.
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+===============+============+=============+===========+============+
| Decomposition | Resolution | Subbands | Keep all | ... to |
| level | level | | Body | decode an |
| | | | Packets | image with |
| | | | with RES | at most |
| | | | equal to | these |
| | | | or less | dimensions |
| | | | than | |
| | | | this | |
| | | | value... | |
+===============+============+=============+===========+============+
| 1 | 5 | HL1,LH1,HH1 | 7 | W x H |
+---------------+------------+-------------+-----------+------------+
| 2 | 4 | HL2,LH2,HH2 | 6 | (W/2) x |
| | | | | (H/2) |
+---------------+------------+-------------+-----------+------------+
| 3 | 3 | HX3 | 5 | (W/4) x |
| | | | | (H/2) |
+---------------+------------+-------------+-----------+------------+
| 4 | 2 | HX4 | 4 | (W/8) x |
| | | | | (H/2) |
+---------------+------------+-------------+-----------+------------+
| 5 | 1 | HX5 | 3 | (W/16) x |
| | | | | (H/2) |
+---------------+------------+-------------+-----------+------------+
| 5 | 0 | LX5 | 2 | (W/32) x |
| | | | | (H/2) |
+---------------+------------+-------------+-----------+------------+
Table 3: Optional discarding of Body Packets based on the value
of the RES field when decoding a reduced resolution image, in the
case where N_L = 5 and some DWT stages consist of only horizontal
transforms. The image has nominal width and height of W x H.
Table 3 illustrates the case where some of DWT stage consist of only
horizontal transforms, as specified at Annex F of [jpeg2000-2].
A receiver can therefore discard all Body Packets where RES is
greater than some threshold value if it is interested in decoding an
image with its resolution reduced by a factor determined by the
threshold value, as illustrated in Table 2 and Table 3.
8.4. Extra information
The receiver MUST accept values XTRAC other than 0 and MUST ignore
the value of XTRAB, whose length is given by XTRAC.
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Future edition of this specification can specify XTRAB contents such
that this content can be ignored by receivers that conform to this
specification.
8.5. Reserved values
The receiver MUST ignore the value of reserved values.
8.6. Extension values
The receiver MUST discard an RTP packet that contains any extension
value.
8.7. Code-block caching
This section applies only if C = 1.
When C = 1, and as specified in Section 7.9, the sender can improve
bandwidth efficiency by only occasionally transmitting code-blocks
corresponding to static portions of the video and otherwise
transmitting empty code-blocks, as defined at Section 7.9.
When decoding a codestream, and for each code-block in the
codestream:
* if the code-block in the codestream is empty, the receiver MUST
replace it with a matching code-block from the cache, if one
exists; or
* if the code-block in the codestream is not empty, the receiver
MUST replace any matching code-block from the cache with the code-
block in the codestream.
Two code-blocks are _matching_ if the following characteristics are
identical for both: spatial coordinates, resolution level, component,
sub-band and value of the TP field of the parent RTP packet.
9. Media Type
9.1. General
This RTP payload format is identified using the media type defined at
Section 9.2, which is registered in accordance with [RFC4855] and
using the template of [RFC6838].
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9.2. Definition
Type name
video
Subtype name
jpeg2000-scl
Required parameters
None
Optional parameters
pixel
Specifies the pixel format used by the video sequence.
The parameter MUST be a URI-reference as specified in
[RFC3986].
If the parameter is a relative-ref as specified in [RFC3986],
then it MUST be equal to one of the pixel formats specified in
Table 5 and the RTP header and payload MUST conform with the
characteristics of that pixel format.
If the parameter is not a relative-ref, the specification of
the pixel format is left to the application that defined the
URI.
If the parameter is not specified, the pixel format is
unspecified.
sample
Specifies the format of the samples in each component of the
codestream.
The parameter MUST be a URI-reference as specified in
[RFC3986].
If the parameter is a relative-ref as specified in [RFC3986],
then it MUST be equal to one of the formats specified in
Appendix C and the stream MUST conform with the characteristics
of that format.
If the parameter is not a relative-ref, the specification of
the sample format is left to the application that defined the
URI.
If the parameter is not specified, the sample format is
unspecified.
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width
Maximum width in pixels of each image. Integer between 0 and
4,294,967,295.
The parameter MUST be a sequence of 1 or more digits.
If the parameter is not specified, the maximum width is
unspecified.
height
Maximum height in pixels of each image. Integer between 0 and
4,294,967,295.
The parameter MUST be a sequence of 1 or more digits.
If the parameter is not specified, the maximum height is
unspecified.
signal
Specifies the sequence of image types.
The parameter MUST be a URI-reference as specified in
[RFC3986].
If the parameter is a relative-ref as specified in [RFC3986],
then it MUST be equal to one of the signal formats specified in
Appendix B and the image sequence MUST conform to that signal
format.
If the parameter is not a relative-ref, the specification of
the pixel format is left to the application that defined the
URI.
If the parameter is not specified, the stream consists of an
arbitrary sequence of image types.
caps
The parameters contains a list of sets of constraints to which
the stream conforms, with each set of constraints identified
using an absolute-URI defined by an application.
The parameter MUST conform to the uri-list syntax expressed
using ABNF ([RFC5234]):
uri-list = absolute-URI *(";" absolute-URI)
Each absolute-URI MUST NOT contain any ";" character.
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The application that defines the absolute-URI MUST associate it
with a set of constraints to which the stream conforms. Such
constraints can, for example, include the maximum height and
width of images.
If the parameter is not specified, constraints, beyond those
specified in this document, are unspecified.
tile
The parameter MUST conform to the tile syntax expressed using
ABNF ([RFC5234]):
tile = tile-index "&" image-siz
tile-index = %x31-39 *%x30-39
image-siz = 1*HEXDIG
If the tile parameter is present, each image MUST correspond to
one tile of a multi-tile image, as defined in Section 6.2.
tile-index is the index of the tile in the multi-tile image.
image-siz contains the SIZ marker segment parameters of the
multi-tile image, encoded as a case insensitive hexadecimal
string.
The SIZ parameters of each single-tile image MUST conform to
the following:
* Xsiz MUST be equal to the smaller of (i) the coordinate of
the right edge of tile index tile-index in the multi-tile
image and (ii) Xsiz of the multi-tile image.
* Ysiz MUST be equal to the smaller of (i) the coordinate of
the bottom edge of tile index tile-index in the multi-tile
image and (ii) Ysiz of the multi-tile image.
* XOsiz MUST be equal to the larger of (i) the coordinate of
the left edge of tile index tile-index in the multi-tile
image and (ii) XOsiz of the multi-tile image.
* YOsiz MUST be equal to the larger of (i) the coordinate of
the top edge of tile index tile-index in the multi-tile
image and (ii) YOsiz of the multi-tile image.
* XTOsiz MUST be equal to the coordinate of the left edge of
tile index tile-index in the multi-tile image.
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* YTOsiz MUST be equal to the coordinate of the top edge of
tile index tile-index in the multi-tile image.
* All other parameters MUST be equal to that in the multi-tile
image.
Figure 4 illustrates an example where a multi-tile image that
consists of two tiles is transmitted as two single-tile images
(images 1 and 2). Figure 5 and Table 4 describe the tile and
SIZ parameter values, respectively.
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(a) Multi-tile image
<----------Xsiz---------->
<----> XTOSiz
+------------------------+
| <---Xtsiz----> |
| xxxxxxxxxxxxxxxxxxxxxxxxxxx
| x T0 x T1 | x
| x #######x####### x
| x #......x......# x
| x #......x......# x
+----xxxxxxxxxxxxxxxxxxxxxxxxxxx
<---XOsiz-->
(b) Single-tile image 1
<-------Xsiz------> +--+
<----> XTOSiz | | Reference grid
+-----------------+ +--+
| <---Xtsiz---->
| xxxxxxxxxxxxxx xxxx
| x T0 x x x Tile area
| x #######x xxxx
| x #......x
| x #......x ####
+----xxxxxxxxxxxxxx #..# Image area
<---XOsiz--> ####
(a) Single-tile image 2
<----------Xsiz---------->
<-----XTOSiz------>
+------------------------+
| |
| xxxxxxxxxxxxx
| x T0 | x
| x####### x
| x......# x
| x......# x
+-----------------xxxxxxxxxxxxx
<-------XOsiz-----X---Xtsiz--->
Figure 4: Ssiz parameters for a multi-tile image and two
corresponding single-tile images 1 and 2.
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NOTE: '\' line wrapping per RFC 8792
tile=0&00000190000000c8000000c800000000000000\
c8000000c800000064000000000001080000
Figure 5: Example tile parameter for a multi-tile image
that consists of two tiles.
+===============+==========+================+================+
| SIZ parameter | Two-tile | Image where | Image where |
| | image | tile-index = 1 | tile-index = 2 |
+===============+==========+================+================+
| XSiz | 400 | 300 | 400 |
+---------------+----------+----------------+----------------+
| YSiz | 200 | 200 | 200 |
+---------------+----------+----------------+----------------+
| XTSiz | 200 | 200 | 200 |
+---------------+----------+----------------+----------------+
| YTSiz | 200 | 200 | 200 |
+---------------+----------+----------------+----------------+
| XOSiz | 200 | 200 | 300 |
+---------------+----------+----------------+----------------+
| YOSiz | 0 | 0 | 0 |
+---------------+----------+----------------+----------------+
| XTOSiz | 100 | 100 | 300 |
+---------------+----------+----------------+----------------+
| YTOSiz | 0 | 0 | 0 |
+---------------+----------+----------------+----------------+
Table 4: Selected SIZ parameters for a two-tile image and two
corresponding single-time images.
cache
The value of the parameter MUST be either false or true.
If the parameter is true, the field C MAY be 0 or 1; otherwise
the field C MUST be 0.
If the parameter is not specified, then the parameter is equal
to false.
Encoding considerations
This media type is framed and binary, see Section 4.8 of
[RFC6838].
Security considerations
See Section 12.
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Interoperability considerations
The RTP stream is a sequence of JPEG 2000 images. An
implementation that conforms to the family of JPEG 2000 standards
can decode and attempt to display each image.
Published specification
This document
Applications that use this media type
video streaming and communication
Person and email address to contact for further information
Pierre-Anthony Lemieux <pal@sandflow.com>
Intended usage
COMMON
Restrictions on Usage
This media type depends on RTP framing, and hence is only defined
for use with RTP as specified at [RFC3550]. Transport within
other framing protocols is not defined at the time.
Author
Pierre-Anthony Lemieux (mailto:pal@sandflow.com)
Change controller
IETF Audio/Video Transport Core Maintenance Working Group
delegated from the IESG.
10. Mapping to the Session Description Protocol (SDP)
The mapping of the payload format media type and its parameters to
SDP, as specified in [RFC8866] MUST be done according to Section 3 of
[RFC4855].
11. IANA Considerations
This memo requests that IANA registers the content type specified at
Section 9. The media type is also requested to be added to the IANA
registry for RTP Payload Format MIME types
(http://www.iana.org/assignments/rtp-parameters).
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12. Security considerations
RTP packets using the payload format specified in this document are
subject to the security considerations discussed in [RFC3550] , and
in any applicable RTP profile such as [RFC3551], [RFC4585],
[RFC3711], [RFC5124]. However, as [RFC7202] discusses, it is not an
RTP payload format's responsibility to discuss or mandate what
solutions are used to meet the basic security goals like
confidentiality, integrity, and source authenticity for RTP in
general. This responsibility lays on anyone using RTP in an
application. They can find guidance on available security mechanisms
and important considerations in [RFC7201]. Applications SHOULD use
one or more appropriate strong security mechanisms. The rest of this
Security Considerations section discusses the security impacting
properties of the payload format itself.
This RTP payload format and its media decoder do not exhibit any
significant non-uniformity in the receiver-side computational
complexity for RTP Packet processing, and thus are unlikely to pose a
denial-of-service threat due to the receipt of pathological data.
Nor does the RTP payload format contain any active content.
Security considerations related to the JPEG 2000 codestream contained
in the payload are discussed at Section 3 of [RFC3745].
13. References
13.1. Normative References
[jpeg2000-1]
ITU-T, "Recommendation ITU-T T.800, JPEG 2000 image coding
system: Core coding system", June 2019.
[jpeg2000-2]
ITU-T, "Recommendation ITU-T T.801, JPEG 2000 image coding
system: Extensions", June 2021.
[jpeg2000-15]
ITU-T, "Recommendation ITU-T T.814, JPEG 2000 image coding
system: High-throughput JPEG 2000", June 2019.
[rec-itu-t-h273]
ITU-T, "Recommendation ITU-T H.273, Coding-independent
code points for video signal type identification", July
2021.
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[jpeg2000-9]
ITU-T, "JPEG 2000 image coding system: Interactivity
tools, APIs and protocols", January 2005.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550,
July 2003, <https://www.rfc-editor.org/info/rfc3550>.
[RFC8866] Begen, A., Kyzivat, P., Perkins, C., and M. Handley, "SDP:
Session Description Protocol", RFC 8866,
DOI 10.17487/RFC8866, January 2021,
<https://www.rfc-editor.org/info/rfc8866>.
[RFC4855] Casner, S., "Media Type Registration of RTP Payload
Formats", RFC 4855, DOI 10.17487/RFC4855, February 2007,
<https://www.rfc-editor.org/info/rfc4855>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008,
<https://www.rfc-editor.org/info/rfc5234>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
13.2. Informative References
[RFC5371] Futemma, S., Itakura, E., and A. Leung, "RTP Payload
Format for JPEG 2000 Video Streams", RFC 5371,
DOI 10.17487/RFC5371, October 2008,
<https://www.rfc-editor.org/info/rfc5371>.
[RFC4175] Gharai, L. and C. Perkins, "RTP Payload Format for
Uncompressed Video", RFC 4175, DOI 10.17487/RFC4175,
September 2005, <https://www.rfc-editor.org/info/rfc4175>.
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[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
Specifications and Registration Procedures", BCP 13,
RFC 6838, DOI 10.17487/RFC6838, January 2013,
<https://www.rfc-editor.org/info/rfc6838>.
[RFC3551] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and
Video Conferences with Minimal Control", STD 65, RFC 3551,
DOI 10.17487/RFC3551, July 2003,
<https://www.rfc-editor.org/info/rfc3551>.
[RFC4585] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey,
"Extended RTP Profile for Real-time Transport Control
Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585,
DOI 10.17487/RFC4585, July 2006,
<https://www.rfc-editor.org/info/rfc4585>.
[RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
Norrman, "The Secure Real-time Transport Protocol (SRTP)",
RFC 3711, DOI 10.17487/RFC3711, March 2004,
<https://www.rfc-editor.org/info/rfc3711>.
[RFC5124] Ott, J. and E. Carrara, "Extended Secure RTP Profile for
Real-time Transport Control Protocol (RTCP)-Based Feedback
(RTP/SAVPF)", RFC 5124, DOI 10.17487/RFC5124, February
2008, <https://www.rfc-editor.org/info/rfc5124>.
[RFC7201] Westerlund, M. and C. Perkins, "Options for Securing RTP
Sessions", RFC 7201, DOI 10.17487/RFC7201, April 2014,
<https://www.rfc-editor.org/info/rfc7201>.
[RFC7202] Perkins, C. and M. Westerlund, "Securing the RTP
Framework: Why RTP Does Not Mandate a Single Media
Security Solution", RFC 7202, DOI 10.17487/RFC7202, April
2014, <https://www.rfc-editor.org/info/rfc7202>.
[RFC3745] Singer, D., Clark, R., and D. Lee, "MIME Type
Registrations for JPEG 2000 (ISO/IEC 15444)", RFC 3745,
DOI 10.17487/RFC3745, April 2004,
<https://www.rfc-editor.org/info/rfc3745>.
[RFC5450] Singer, D. and H. Desineni, "Transmission Time Offsets in
RTP Streams", RFC 5450, DOI 10.17487/RFC5450, March 2009,
<https://www.rfc-editor.org/info/rfc5450>.
Appendix A. Pixel formats
Table 5 defines pixel formats.
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+=============+=======+=======+=======+=======+===+=====+=========+
| NAME | SAMP | COMPS | TRANS | PRIMS |MAT| VFR | Mapping |
| | | | | | | | in |
| | | | | | | | Table 1 |
+=============+=======+=======+=======+=======+===+=====+=========+
| rgb444sdr | 4:4:4 | RGB | 1 | 1 |0 | 0, | RGB |
| | | | | | | 1 | |
+-------------+-------+-------+-------+-------+---+-----+---------+
| rgb444wcg | 4:4:4 | RGB | 1 | 9 |0 | 0, | RGB |
| | | | | | | 1 | |
+-------------+-------+-------+-------+-------+---+-----+---------+
| rgb444pq | 4:4:4 | RGB | 16 | 9 |0 | 0, | RGB |
| | | | | | | 1 | |
+-------------+-------+-------+-------+-------+---+-----+---------+
| rgb444hlg | 4:4:4 | RGB | 18 | 9 |0 | 0, | RGB |
| | | | | | | 1 | |
+-------------+-------+-------+-------+-------+---+-----+---------+
| ycbcr420sdr | 4:2:0 | YCbCr | 1 | 1 |1 | 0 | YCbCr |
+-------------+-------+-------+-------+-------+---+-----+---------+
| ycbcr422sdr | 4:2:2 | YCbCr | 1 | 1 |1 | 0 | YCbCr |
+-------------+-------+-------+-------+-------+---+-----+---------+
| ycbcr422wcg | 4:2:2 | YCbCr | 1 | 9 |9 | 0 | YCbCr |
+-------------+-------+-------+-------+-------+---+-----+---------+
| ycbcr422pq | 4:2:2 | YCbCr | 16 | 9 |9 | 0 | YCbCr |
+-------------+-------+-------+-------+-------+---+-----+---------+
| ycbcr422hlg | 4:2:2 | YCbCr | 18 | 9 |9 | 0 | YCbCr |
+-------------+-------+-------+-------+-------+---+-----+---------+
Table 5: Defined pixel formats
Each pixel format is characterized by the following:
NAME
Identifies the pixel format
COMPS
RGB Each codestream contains exactly three components, associated
with the R, G and B color channels, in order.
YCbCr Each codestream contains exactly three components,
associated with the Y, C_b and C_r color channels, in order.
SAMP
4:2:0 The C_b and C_r color channels are subsampled horizontally
and vertically by 1/2.
4:2:2 The C_b and C_r color channels are subsampled horizontally
by 1/2.
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4:4:4 No color channels are sub-sampled.
TRANS
Identifies the transfer characteristics allowed by the pixel
format, as defined at [rec-itu-t-h273]
PRIMS
Identifies the color primaries allowed by the pixel format, as
defined at [rec-itu-t-h273]
MAT
Identifies the matrix coefficients allowed by the pixel format, as
defined at [rec-itu-t-h273]
VFR
Allows values of the VideoFullRangeFlag defined at
[rec-itu-t-h273]
Appendix B. Signal formats
prog
The stream MUST only consist of a sequence of progressive frames.
psf
Progressive segmented frame (PsF) stream. The stream MUST only
consist of an alternating sequence of first segment and second
segment.
tff
Interlaced stream. The stream MUST only consist of an alternating
sequence of first field and second field, where the first line of
the first field is the first line of the frame.
bff
Interlaced stream. The stream MUST only consist of an alternating
sequence of first field and second field, where the first line of
the first field is the second line of the frame.
Appendix C. Sample formats
8
All components consist of unsigned 8-bit integer samples.
10
All components consist of unsigned 10-bit integer samples.
12
All components consist of unsigned 12-bit integer samples.
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16
All components consist of unsigned 16-bit integer samples.
Appendix D. Summary of Changes (Informative)
D.1. Introduction
This Appendix summarizes substantive changes across revisions of this
specification. This summary is informative and not intended to be
exhaustive.
D.2. Changes from draft-ietf-avtcore-rtp-j2k-scl-00
* Allow multi-tile images in a single stream, in addition to
allowing multi-tile images to be transmitted as multiple single-
tile streams, as specified at Section 6.2.
* Fix incorrect TRANS values at Table 5.
Authors' Addresses
Pierre-Anthony Lemieux (editor)
Sandflow Consulting LLC
San Mateo, CA
United States of America
Email: pal@sandflow.com
David Scott Taubman
University of New South Wales
Sydney
Australia
Email: d.taubman@unsw.edu.au
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