RTP Payload Format for ISO/IEC 21122 (JPEG XS)
draft-lugan-payload-rtp-jpegxs-00
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
|
|
|---|---|---|---|
| Authors | Sébastien Lugan , Gaël Rouvroy , Antonin Descampe , Thomas Richter , Alexandre Willeme | ||
| Last updated | 2018-05-30 | ||
| Replaced by | draft-ietf-payload-rtp-jpegxs, RFC 9134 | ||
| RFC stream | (None) | ||
| Formats | |||
| Additional resources | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-lugan-payload-rtp-jpegxs-00
Payload Working Group S. Lugan
Internet-Draft G. Rouvroy
Intended status: Standards Track A. Descampe
Expires: December 1, 2018 intoPIX
T. Richter
IIS
A. Willeme
UCL/ICTEAM
May 30, 2018
RTP Payload Format for ISO/IEC 21122 (JPEG XS)
draft-lugan-payload-rtp-jpegxs-00
Abstract
This document specifies a Real-Time Transport Protocol (RTP) payload
format to be used for transporting ISO/IEC 21122 (JPEG XS) encoded
video. ISO/IEC 21122 (JPEG XS) is a low-latency, lightweight image
coding system allowing for an increased resolution and frame rate,
while offering visually lossless quality with reduced amount of
ressources such as power and bandwidth.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 1, 2018.
Copyright Notice
Copyright (c) 2018 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
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publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions, Definitions, and Abbreviations . . . . . . . . . 3
2.1. Application Data Unit . . . . . . . . . . . . . . . . . . 3
2.2. JPEG XS codestream . . . . . . . . . . . . . . . . . . . 3
2.3. JPEG XS frame . . . . . . . . . . . . . . . . . . . . . . 3
2.4. Marker . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.5. Marker Sequence . . . . . . . . . . . . . . . . . . . . . 3
2.6. JPEG XS Header . . . . . . . . . . . . . . . . . . . . . 3
2.7. Video Essence Box . . . . . . . . . . . . . . . . . . . . 4
2.8. JPEG XS Header Segment . . . . . . . . . . . . . . . . . 4
2.9. Slice . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.10. Slice group . . . . . . . . . . . . . . . . . . . . . . . 4
2.11. Fragment . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Media Format Description . . . . . . . . . . . . . . . . . . 4
3.1. Image Data Structures . . . . . . . . . . . . . . . . . . 4
3.2. Codestream . . . . . . . . . . . . . . . . . . . . . . . 6
3.3. Video Essence Box . . . . . . . . . . . . . . . . . . . . 6
3.4. JPEG XS Stream . . . . . . . . . . . . . . . . . . . . . 7
3.5. Fragments . . . . . . . . . . . . . . . . . . . . . . . . 7
4. Payload Format . . . . . . . . . . . . . . . . . . . . . . . 7
4.1. RTP Header Usage . . . . . . . . . . . . . . . . . . . . 8
4.2. Payload Header . . . . . . . . . . . . . . . . . . . . . 8
4.3. Payload Data . . . . . . . . . . . . . . . . . . . . . . 12
4.4. Traffic Shaping and Delivery Timing . . . . . . . . . . . 13
5. Congestion Control Considerations . . . . . . . . . . . . . . 13
6. Payload Format Parameters . . . . . . . . . . . . . . . . . . 14
6.1. Media Type Definition . . . . . . . . . . . . . . . . . . 14
6.2. Mapping to SDP . . . . . . . . . . . . . . . . . . . . . 14
6.2.1. General . . . . . . . . . . . . . . . . . . . . . . . 14
6.2.2. Media type and subtype . . . . . . . . . . . . . . . 14
6.2.3. Traffic shaping . . . . . . . . . . . . . . . . . . . 14
6.2.4. Other parameters . . . . . . . . . . . . . . . . . . 14
6.2.5. Offer/Answer Considerations . . . . . . . . . . . . . 15
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
8. Security Considerations . . . . . . . . . . . . . . . . . . . 15
9. RFC Editor Considerations . . . . . . . . . . . . . . . . . . 16
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
10.1. Normative References . . . . . . . . . . . . . . . . . . 16
10.2. Informative References . . . . . . . . . . . . . . . . . 18
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10.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction
This document specifies a payload format for packetization of ISO/IEC
21122 (JPEG XS) [ISO21122-1] encoded video signals into the Real-time
Transport Protocol (RTP) [RFC3550].
2. Conventions, Definitions, and Abbreviations
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
2.1. Application Data Unit
See Real-time Transport Protocol (RTP) [RFC3550], though for the
purpose of this document identical to a JPEG XS frame.
2.2. JPEG XS codestream
A sequence of bytes representing compressed images formatted
according to ISO/IEC 21122-1.
2.3. JPEG XS frame
Concatenation of the Video Essence box and a JPEG XS codestream
2.4. Marker
A two-byte functional sequence that is part of a JPEG XS codestream
starting with a 0xff byte and a subsequent byte defining its
function.
2.5. Marker Sequence
A marker along with a 16-bit marker size and payload data following
the size.
2.6. JPEG XS Header
A sequence of bytes at the beginning of each JPEG XS codestream
encoded in multiple markers and marker sequences that does not carry
entropy coded data, but metadata such as the frame dimension and
component precision.
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2.7. Video Essence Box
A ISO super box in the sense of ISO/IEC 15444-1 defined in ISO/IEC
21122-3 that includes metadata required to play back a JPEG XS video
stream, such as its color space, its buffer model and its frame rate.
2.8. JPEG XS Header Segment
The concatenation of the Video Essence Box and the JPEG XS Header.
2.9. Slice
The smallest independently decodable unit of a JPEG XS stream.
2.10. Slice group
A contiguous sequence of slices belonging to a fragment, where sizing
constraints on the slice group are derived from the fragment sizing
constraints (see there).
2.11. Fragment
A slice group along with the metadata immediately preceeding and/or
following it, sized such that the first byte of the fragment and the
byte following the last byte of the fragment are in two distinct
packets, except for the last fragment of an Application Dependent
Unit (ADU).
3. Media Format Description
3.1. Image Data Structures
JPEG XS is a low-latency lightweight image coding system for coding
continuous-tone grayscale or continuous-tone color digital images.
This coding system provides an efficient representation of image
signals through the mathematical tool of wavelet analysis. The
wavelet filter process separates each component into multiple bands,
where each band consists of multiple coefficients describing the
image signal of a given component within a frequency domain specific
to the wavelet filter type, i.e. the particular filter corresponding
to the band.
Wavelet coefficients are grouped into precincts, where each precinct
includes all coefficients over all bands that contribute to a spatial
region of the image.
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One or multiple Precincts are furthermore combined into slices
consisting of an integral number of precincts. Precincts do not
cross slice boundaries, and wavelet coefficients in precincts that
are part of different slices can be decoded independently from each
other. Note, however, that the wavelet transformation runs across
slice boundaries. A slice always extends over the full width of the
image, but may only cover parts of its height.
A slice is the smallest indepedently decodable unit of a JPEG XS
codestream, bearing in mind that it decodes to wavelet coefficients
which still require inverse wavelet filtering to give an image.
Multiple contiguous slices are combined into slice groups. Slice
groups along with preceeding and/or following metadata form
fragments. Fragments, and by that slice groups, are sized such that
each RTP packet contains at most two fragments. This is equivalent
to stating that the first byte of the fragment and the byte following
the last byte of a fragment are part of two distinct packets, except
for the last fragment.
Figure 1 shows an example of packets, slices and slice groups. In
this Figure, M indicates metadata preceeding or following slice
groups, SlcGrp the slice groups and Slc the slices. As seen there, a
fragment may contain more than one slice if the slices are too short
to fill up an entire packet, and fragment and packet boundaries need
only to align at the start and the end of the ADU. Fragments may
extend over more than two packets, depending on their size, but a
packet never contains more than two fragments. Slice group and
fragment boundaries conincide, except for the first and the last
fragment, which include additional metadata. Unlike regularly sized
packets, the fragment and the slice group size may vary.
<------------------- Application Data Unit (ADU) ------------------->
+-----------+-----------+-----------+-----------+-/ /-+-------------+
| Packet #0 | Packet #1 | Packet #2 | Packet #3 | | Packet #n-1 |
+-----------+---+-------+-----------+---+-------+-/ /-+-------------+
| Fragment #0 | Fragment #1 | Fragment #m-1 |
+---+-----------+-----------------------+---------/ /-----------+---+
| M | SlcGrp #0 | SlcGrp #1 | SlcGrp #m-1 | M |
+---+-----------+-----------------------+---------/ /-----------+---+
| M |Slc#0 Slc#1| Slc #2 | Slc #k-1 | M |
+---+-----------+-----------------------+---------/ /-----------+---+
Figure 1: Slice Groups and Fragments
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3.2. Codestream
The codestream is a linear stream of bits from the first bit to the
last bit representing the sample values of a single frame, bare any
interpretation relative to a colorspace. It can be divided into
(8-bit) bytes, starting with the first bit of the codestream. Bits
within bytes are enumerated from the least significant bit (LSB) to
the most significant bit (MSB), with the least significant bit having
the index zero. Bits within bytes are transmitted in decreasing
magnitude order, with the MSB of a byte transmitted first and the LSB
transmitted last. This implies, in particular, that fields that are
longer than 8 bits are transmitted with the most significant byte
first. This is also denoted as "big endian" format.
The codestream consists of multiple syntax elements: markers, marker
segments and entropy coded data.
Markers inidicate syntactical elements of the codestreams. They
consist of an 0xff-byte and a second byte defining the nature of the
marker. The SOC marker (hex 0xff10) indicates the start of the
codestream, the EOC marker (hex 0xff11) its end.
Marker segments are markers along with a length field and payload
data following the length field. Marker segments define control
information necessary to steer the decoding process. The JPEG XS
specification ISO/IEC 21122-1 [ISO21122-1] defines additional markers
beyond SOC and EOC.
The sequence of bytes made up by all markers that precede the entropy
coded data is also denoted as JPEG XS Header in the following.
Entropy coded data represents the image data itself. The data is
organized in slices, where each slice consists of a slice header that
starts with the SLC marker (hex 0xff20) and payload data, consisting
of encoded wavelet coefficients.
The overall codestream format, including the definition of all
markers, is further defined in ISO/IEC 21122-1 [ISO21122-1].
3.3. Video Essence Box
While the information defined in the codestream is sufficient to
reconstruct the sample values of one video frame, the interpretation
of the samples remains undefined by the codestream itself. This
interpretation, including the color space, frame rate and other
information significant to play a JPEG XS stream are contained in the
Video Essence box, which preceeds each JPEG XS codestream. The
syntax of the Video Essence box follows ISO/IEC 15444-1 [ISO15444-1];
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it consists of multiple subboxes, each with a particular meaning.
Its contents, in particular its subboxes are defined in ISO/IEC
21122-3 [ISO21122-3].
3.4. JPEG XS Stream
A JPEG XS stream is a sequence of frames, where each frame is coded
independently of each other. For the purpose of RTP transport, each
frame forms an Application Dependent Unit (ADU).
A JPEG XS frame consists of the concatenation of a Video Essence box
(as defined in ISO/IEC 21122-3 [ISO21122-3]) and a JPEG XS codestream
(as defined in ISO/IEC 21122-1 [ISO21122-1]). As defined above, the
codestream consists of a JPEG XS header, one or multiple slice
groups, and an EOC marker.
3.5. Fragments
For the purpose of transport, JPEG XS frames are separated into one
or multiple fragments such that the start of the fragment and the
byte following the last byte of a fragment are in two distinct
packets used for RTP transport, except for the last fragment of a
JPEG XS frame which may be contained in only a single packet.
A fragment consists of all metadata preceeding its first slice, one
or multiple slices, and potentially the EOC marker following the last
slice.
The collection of slices in a fragment is also denoted as slice
group, and slice groups within a frame are enumerated from top to
bottom by the slice group counter. That is, the first slice group of
a frame is slice group #0, and the slice group counter increments by
1 from top to bottom for each slice group, and by that for each
fragment.
NOTE: By this definition, the first fragment consists of at least the
Video Essence Box, the JPEG XS header, and the first slice group.
The last fragment consists of at least the last slice group and the
EOC marker. In case the frame consists of only a single fragment,
this fragment contains both the JPEG XS header segment and the EOC.
4. Payload Format
This section specifies the payload format for JPEG XS video streams
over the Real-time Transport Protocol (RTP) [RFC3550].
In order to be transported over RTP, each JPEG XS stream is
transported in a distinct RTP stream, identified by a distinct SSRC.
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Each of those RTP streams is divided into Application Data Units
(ADUs). Each ADU shall correspond to a single JPEG XS frame.
Each ADU is split into packets, depending e.g. on the Maximum
Transmission unit (MTU) of the network. Every packet shall have same
size, except the last packet of every ADU which could be shorter.
Packet boundaries shall coincide with ADU boundaries, i.e. the first
byte of an ADU shall be the first byte of payload data within a JPEG
XS segment.
A JPEG XS frame, and by that each ADU, shall consist of a Video
Essence box defining the meta information required for playback,
concatenated to the JPEG XS codestream, defining the sample values of
the picture.
The JPEG XS stream, as defined in ISO/IEC 21122-1 [ISO21122-1] itself
consists of a JPEG XS header that defines picture parameters, and one
or multiple slices that contain the entropy coded picture data and an
EOC marker. A slice is the smallest independently decodable unit of
a JPEG XS codestream.
JPEG XS frames are separated into fragments such that the first byte
of a fragment and the byte following the last byte of a fragment are
in two disinct packets, except for the last fragment of the frame.
Fragments are enumerated by the slice group index of the slice group
contained within.
4.1. RTP Header Usage
The SSRC RTP field is used to discriminate each separate JPEG XS
video stream from others. Within a specific JPEG XS video stream,
identified by its SSRC, the picture counter field is used to identify
to which picture a packet corresponds to.
4.2. Payload Header
The following figure illustrates the RTP payload header used in order
to transport each JPEG XS video stream (identified by a distinct
SSRC).
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+---+-+-+-------+-+-------------+-------------------------------+
| V |P|X| CC |M| PT | Sequence number |
+---+-+-+-------+-+-------------+-------------------------------+
| Timestamp |
+---------------------------------------------------------------+
| Synchronization source (SSRC) identifier |
+-----+-+-+---------+---------------------+-+-------------------+
| Ver |f|c| SlcGrp | SlcGrpOffset |C| Picture Counter |
+-----+-+-+---------+---------------------+-+-------------------+
| Data |
+---------------------------------------------------------------+
Figure 2: RTP and payload headers
The version (V), padding (P), extension (X), CSRC count (CC),
sequence number and synchronization source (SSRC) fields follow their
respective definitions in RFC 3550 [RFC3550].
The timestamp should be based on a globally synchronized 90 kHz clock
reference, and should correspond to the number of cycles since the
SMPTE Epoch (as per defined in SMPTE ST 2059-1:2015 [SMPTE-ST2059])
modulo 2^32:
timestamp = floor((now - epoch)*90000) % 2^32
where now and epoch are real numbers expressed in seconds, now being
the current timestamp and epoch the reference timestamp and floor
indicates rounding to the next lower integer.
As per specified in RFC 3550 [RFC3550] and RFC 4175 [RFC4175], the
RTP timestamp designates the sampling instant of the first octet of
the picture to which the RTP packet belongs. Packets shall not
include data from multiple frames, and all packets belonging to the
same frame shall have the same timestamp. Several successive RTP
packets will consequently have equal timestamps if they belong to the
same picture (that is until the marker bit is set to 1, marking the
last packet of the frame), and the timestamp is only increased when a
new frame begins.
If the sampling instant does not correspond to an integer value of
the clock, the value shall be truncated to the next lowest integer,
with no ambiguity.
The remaining fields are defined as follows:
+-----------------+----------+--------------------------------------+
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| Field | Width | Description |
+-----------------+----------+--------------------------------------+
| Marker (M) | 1 bit | The marker bit is used to indicate |
| | | the last packet of a frame. This |
| | | enables a decoder to finish decoding |
| | | the picture, where it otherwise may |
| | | need to wait for the next packet to |
| | | explicitly know that the frame is |
| | | finished. |
| Payload Type | 7 bits | A dynamically allocated payload type |
| (PT) | | field that designates the payload as |
| | | JPEG XS video. |
| Vers | 3 bits | This field indicates the version |
| | | number of the payload header. The |
| | | value of this field shall be 0 for |
| | | the purpose of this edition of the |
| | | RFC. |
| f | 1 bit | The f field shall be set if a new |
| | | fragment is started within this |
| | | packet, i.e. if this packet contains |
| | | the first byte of a fragment. NOTE: |
| | | The JPEG XS header segment and the |
| | | first slice group form a fragment. |
| | | For that reason, the f-bit remains |
| | | unset in the packet that contains |
| | | the first byte of slice group 0 but |
| | | does not also contains the first |
| | | byte of the Video Essence box. All |
| | | other slice groups form fragments of |
| | | their own. The f bit allows a quick |
| | | identificaiton of packets that start |
| | | a fragment. The SliceGrpStart field |
| | | (see below) can be used to identify |
| | | the start of a slice group. |
| c | 1 bit | The c field is a one-bit field that |
| | | is set if the fragment to which the |
| | | first byte of the packet belongs |
| | | extends througout a subsequent |
| | | packet. |
| SlcGrp | 5 bits | The SlcGrp (Slice Group) field |
| | | contains the slice group index |
| | | modulo 64 that is contained in the |
| | | fragment that is started in this |
| | | packet. If no fragment starts in |
| | | this packet, it contains the slice |
| | | group index modulo 64 of the slice |
| | | group that is contained in the |
| | | fragment to which the first byte of |
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| | | the payload data of this packet |
| | | belongs. |
| SlcGrpOffset | 11 bits | This field indicates the byte offset |
| | | of the slice header marker (SLH, hex |
| | | 0xff20, see ISO/IEC 21122-1 |
| | | [ISO21122-1]) of the slice group |
| | | that starts in this packet, relative |
| | | to the start of the packet. If no |
| | | slice group starts in this packet, |
| | | this field shall be 0. NOTE: Since |
| | | the payload data has a non-zero |
| | | offset within a packet, this field |
| | | can also be used to identify whether |
| | | a slice group starts in a packet. If |
| | | 0, no slice group starts in this |
| | | packet. Consequently, for slice |
| | | groups with a non-zero slice group |
| | | index, this field will be non-zero |
| | | if and only if the f-field is set. |
| | | For the first slice group of a |
| | | frame, however, the f bit indicates |
| | | the start of the fragment. whereas |
| | | this field indicates the start of |
| | | the slice group. Due to the non-zero |
| | | size of the JPEG XS header segment, |
| | | this needs not to happen in the same |
| | | packet. |
| C | 1 bit | The C flag in the payload header |
| | | shall be set if the frame to which |
| | | the first byte of the packet belongs |
| | | extends througout a subsequent |
| | | packet. Consequently, the last |
| | | packet of an ADU is the only packet |
| | | that does not have this bit set. |
| Picture number | 10 bits | Counter indicating the current |
| | | picture number modulo 2^11. The |
| | | picture number is incremented by one |
| | | at the beginning of each frame, and |
| | | stays constant throuout all packets |
| | | that contribute to to the same |
| | | frame. |
+-----------------+----------+--------------------------------------+
Table 1: Payload header fields description
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4.3. Payload Data
The payload data of a JPEG XS transport stream consists of a
concatenation of multiple JPEG XS Frames.
Each JPEG XS frame is the concatenation of multiple fragments where
each fragment contains one and only one slice group. The first
fragment of a frame also contains the Video Essence box and the JPEG
XS header, the last fragment also contains the EOC marker. Figure 3
depicts this layout.
Fragments may extend over multiple RTP packets. In particular, slice
groups and by that fragments have to be sized such that the first
byte of a fragment and the byte following the last byte of a fragment
are in two distinct packets.
The start of a fragment can be identified by the "f" bit in the
Payload header, the start of a slice group within a packet and its
location in the packet by the SliceGrpStart field in the same Payload
header.
^ +-------------------------------------------+ ^
| | Video Essence Box | |
| | +-------------------------------------+ | |
| | | Sub boxes of the Video Essence Box | | |
Frag- | +-------------------------------------+ | JPEG
ment | : additional sub-boxes of the VE-Box : | XS
#0 | +-------------------------------------+ | Header
| | | Seg-
| +-------------------------------------------+ ment
| | JPEG XS Header | |
| | +-------------------------------------+ | |
| | | SOC Marker | | |
| | +-------------------------------------+ | |
| | : Additional Marker Segments : | |
| | +-------------------------------------+ | |
| | | |
| +-------------------------------------------+ v
| | Slice Group #0 |
| | +-------------------------------------+ |
| | | Slice #0 of Slice Group #0 | |
| | | +-------------------------------+ | |
| | | | SLH Marker | | |
| | | +-------------------------------+ | |
| | | : Entropy Coded Data : | |
| | | +-------------------------------+ | |
| | +-------------------------------------+ |
| | | Slice #1 of Slice Group #0 | |
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| | : : |
| | +-------------------------------------+ |
| | | Slice #n-1 of Slice Group #0 | |
| | : : |
v | +-------------------------------------+ |
^ +-------------------------------------------+
| | Slice Group #1 |
Frag- : :
ment : :
#1 : :
| : :
v +-------------------------------------------+
: :
^ +-------------------------------------------+
| | Slice Group #n-1 |
Frag- : :
ment : :
#n-1 +-------------------------------------------+
| | EOC Marker |
v +-------------------------------------------+
Figure 3: JPEG XS Payload Data
4.4. Traffic Shaping and Delivery Timing
The traffic shaping and delivery timing shall be in accordance with
the Network Compatibility Model compliance definitions specified in
SMPTE ST 2110-21 [SMPTE-ST2110-21] for either Narrow Linear Senders
(Type NL) or Wide Senders (Type W).
Note: The Virtual Receiver Buffer Model compliance definitions of ST
2110-21 do not apply.
5. Congestion Control Considerations
Congestion control for RTP SHALL be used in accordance with RFC 3550
[RFC3550], and with any applicable RTP profile: e.g., RFC 3551
[RFC3551]. An additional requirement if best-effort service is being
used is users of this payload format MUST monitor packet loss to
ensure that the packet loss rate is within acceptable parameters.
Circuit Breakers [RFC8083] is an update to RTP [RFC3550] that defines
criteria for when one is required to stop sending RTP Packet Streams.
The circuit breakers is to be implemented and followed.
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6. Payload Format Parameters
6.1. Media Type Definition
Type name: video
Subtype name: jpeg-xs
Encoding considerations:
This media type is framed and binary; see Section 4.8 in RFC 6838
[RFC6838].
Security considerations:
Please see the Security Considerations section in RFC XXXX
6.2. Mapping to SDP
6.2.1. General
A Session Description Protocol (SDP) object shall be created for each
RTP stream and it shall be in accordance with the provisions of SMPTE
ST 2110-10 [SMPTE-ST2110-10].
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:
6.2.2. Media type and subtype
The media type ("video") goes in SDP "m=" as the media name.
The media subtype ("jpeg-xs") 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 90 kHz clock.
6.2.3. Traffic shaping
The SDP object shall include the TP parameter and may include the
CMAX parameter as specified in SMPTE ST 2110-21 [SMPTE-ST2110-21].
6.2.4. Other parameters
The SDP object shall include the following payload-format-specific
parameter in the a=fmtp line:
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SSN SMPTE Standard Number in the format: ST<number>-<part>:<year>
e.g. ST2110-20:2017
The number shall be that of the JPEG XS standard
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.
6.2.5. Offer/Answer Considerations
The following considerations apply when using SDP offer/answer
procedures [RFC3264] to negotiate the use of the JPEG XS payload in
RTP:
o The "encode" parameter can be used for sendrecv, sendonly, and
recvonly streams. Each encode type MUST use a separate payload
type number.
o Any unknown parameter in an offer MUST be ignored by the receiver
and MUST NOT be included in the answer.
7. IANA Considerations
This memo requests that IANA registers video/jpeg-xs as specified in
Section 6.1. The media type is also requested to be added to the
IANA registry for "RTP Payload Format MIME types" [1].
8. Security Considerations
RTP packets using the payload format defined in this specification
are subject to the security considerations discussed in the RTP
specification [RFC3550] and in any applicable RTP profile such as
RTP/AVP [RFC3551], RTP/AVPF [RFC4585], RTP/SAVP [RFC3711], or RTP/
SAVPF [RFC5124]. This implies that confidentiality of the media
streams is achieved by encryption.
However, as "Securing the RTP Framework: Why RTP Does Not Mandate a
Single Media Security Solution" [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 lies on anyone using RTP in an application. They can
find guidance on available security mechanisms and important
considerations in "Options for Securing RTP Sessions" [RFC7201].
Applications SHOULD use one or more appropriate strong security
mechanisms.
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This payload format and the JPEG XS encoding do not exhibit any
substantial non-uniformity, either in output or in complexity to
perform the decoding operation and thus are unlikely to pose a
denial-of-service threat due to the receipt of pathological
datagrams.
It is important to note that HD or UHDTV JPEG XS-encoded video can
have significant bandwidth requirements (typically more than 1 Gbps
for ultra high-definition video, especially if using high framerate).
This is sufficient to cause potential for denial-of-service if
transmitted onto most currently available Internet paths.
Accordingly, if best-effort service is being used, users of this
payload format MUST monitor packet loss to ensure that the packet
loss rate is within acceptable parameters. Packet loss is considered
acceptable if a TCP flow across the same network path, and
experiencing the same network conditions, would achieve an average
throughput, measured on a reasonable timescale, that is not less than
the RTP flow is achieving. This condition can be satisfied by
implementing congestion control mechanisms to adapt the transmission
rate (or the number of layers subscribed for a layered multicast
session), or by arranging for a receiver to leave the session if the
loss rate is unacceptably high.
This payload format may also be used in networks that provide
quality-of-service guarantees. If enhanced service is being used,
receivers SHOULD monitor packet loss to ensure that the service that
was requested is actually being delivered. If it is not, then they
SHOULD assume that they are receiving best-effort service and behave
accordingly.
9. RFC Editor Considerations
Note to RFC Editor: This section may be removed after carrying out
all the instructions of this section.
RFC XXXX is to be replaced by the RFC number this specification
receives when published.
10. References
10.1. Normative References
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[ISO15444-1]
International Organization for Standardization (ISO) -
International Electrotechnical Commission (IEC),
"Information technology - JPEG 2000 image coding system:
Core coding system", ISO/IEC IS 15444-1, 2016,
<https://www.iso.org/standard/70018.html>.
[ISO21122-1]
International Organization for Standardization (ISO) -
International Electrotechnical Commission (IEC),
"Information technology - Low-latency lightweight image
coding system - Part 1: Core coding system", ISO/IEC DIS
21122-1, under development,
<https://www.iso.org/standard/74535.html>.
[ISO21122-3]
International Organization for Standardization (ISO) -
International Electrotechnical Commission (IEC),
"Information technology - Low-latency lightweight image
coding system - Part 3: Transport and container formats",
ISO/IEC NP 21122-3, under development,
<https://www.iso.org/standard/74537.html>.
[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>.
[RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
with Session Description Protocol (SDP)", RFC 3264,
DOI 10.17487/RFC3264, June 2002,
<https://www.rfc-editor.org/info/rfc3264>.
[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>.
[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>.
[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>.
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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>.
[RFC8083] Perkins, C. and V. Singh, "Multimedia Congestion Control:
Circuit Breakers for Unicast RTP Sessions", RFC 8083,
DOI 10.17487/RFC8083, March 2017,
<https://www.rfc-editor.org/info/rfc8083>.
[SMPTE-ST2110-10]
Society of Motion Picture and Television Engineers, "SMPTE
Standard - Professional Media Over Managed IP Networks:
System Timing and Definitions", SMPTE ST 2110-10:2017,
2017, <https://doi.org/10.5594/SMPTE.ST2110-10.2017>.
[SMPTE-ST2110-21]
Society of Motion Picture and Television Engineers, "SMPTE
Standard - Professional Media Over Managed IP Networks:
Traffic Shaping and Delivery Timing for Video", SMPTE ST
2110-21:2017, 2017,
<https://doi.org/10.5594/SMPTE.ST2110-21.2017>.
10.2. Informative References
[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>.
[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>.
[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>.
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[SMPTE-ST2059]
Society of Motion Picture and Television Engineers, "SMPTE
Standard - Generation and Alignment of Interface Signals
to the SMPTE Epoch", SMPTE ST 2059-1:2015, 2015,
<https://doi.org/10.5594/SMPTE.ST2059-1.2015>.
10.3. URIs
[1] http://www.iana.org/assignments/rtp-parameters
Authors' Addresses
Sebastien Lugan
intoPIX S.A.
Rue Emile Francqui, 9
1435 Mont-Saint-Guibert
Belgium
Phone: +32 10 23 84 70
Email: s.lugan@intopix.com
URI: http://www.intopix.com
Gael Rouvroy
intoPIX S.A.
Rue Emile Francqui, 9
1435 Mont-Saint-Guibert
Belgium
Phone: +32 10 23 84 70
Email: g.rouvroy@intopix.com
URI: http://www.intopix.com
Antonin Descampe
intoPIX S.A.
Rue Emile Francqui, 9
1435 Mont-Saint-Guibert
Belgium
Phone: +32 10 23 84 70
Email: a.descampe@intopix.com
URI: http://www.intopix.com
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Thomas Richter
Fraunhofer IIS
Am Wolfsmantel 33
91048 Erlangen
Germany
Phone: +49 9131 776 5126
Email: thomas.richter@iis.fraunhofer.de
URI: https://www.iis.fraunhofer.de/
Alexandre Willeme
Universite catholique de Louvain
Place du Levant, 2 - bte L5.04.04
1348 Louvain-la-Neuve
Belgium
Phone: +32 10 47 80 82
Email: alexandre.willeme@uclouvain.be
URI: https://uclouvain.be/en/icteam
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