MoQ Media Interop
draft-cenzano-moq-media-interop-00
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| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Jorge Cenzano Ferret , Alan Frindell | ||
| Last updated | 2024-10-21 | ||
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| Intended RFC status | (None) | ||
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| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
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draft-cenzano-moq-media-interop-00
Media Over QUIC J. Cenzano-Ferret
Internet-Draft A. Frindell
Intended status: Informational Meta
Expires: 24 April 2025 21 October 2024
MoQ Media Interop
draft-cenzano-moq-media-interop-00
Abstract
This protocol can be used to send and receive video and audio over
Media over QUIC Transport [MOQT].
About This Document
This note is to be removed before publishing as an RFC.
The latest revision of this draft can be found at
https://afrind.github.io/draft-cenzano-media-interop/draft-cenzano-
moq-media-interop.html. Status information for this document may be
found at https://datatracker.ietf.org/doc/draft-cenzano-moq-media-
interop/.
Discussion of this document takes place on the Media Over QUIC
Working Group mailing list (mailto:moq@ietf.org), which is archived
at https://mailarchive.ietf.org/arch/browse/moq/. Subscribe at
https://www.ietf.org/mailman/listinfo/moq/.
Source for this draft and an issue tracker can be found at
https://github.com/afrind/draft-cenzano-media-interop.
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 24 April 2025.
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Copyright Notice
Copyright (c) 2024 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
and restrictions with respect to this document. Code Components
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Protocol Operation . . . . . . . . . . . . . . . . . . . . . 3
2.1. Track Names . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Mapping Tracks to MoQT Object Model . . . . . . . . . . . 3
2.3. Timestamps . . . . . . . . . . . . . . . . . . . . . . . 3
2.4. Object Format . . . . . . . . . . . . . . . . . . . . . . 4
3. Video H264 in AVCC with WCP Payload Format . . . . . . . . . 4
4. Audio Opus bitstream Payload Format . . . . . . . . . . . . . 5
5. Conventions and Definitions . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Normative References . . . . . . . . . . . . . . . . . . 6
8.2. Informative References . . . . . . . . . . . . . . . . . 7
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
This protocol specifies a simple mechanism for sending media (video
and audio) over MOQT for both live-streaming and VC use cases. The
protocol is flexible in order to support this range of use cases.
Media parameters can be updated in the middle of a the track (ex:
frame rate, resolution, codec, etc)
The protocol defines a low overhead packaging format optimized for
WebCodecs called WCP that is extensible to other formats such as
FMP4. This is not LoC [LOC], but will eventually be merged with that
specification.
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2. Protocol Operation
2.1. Track Names
The publisher selects a namespace of their choosing, and sends an
ANNOUNCE message for this namespace. Since MoQT tracks are
immutable, each new broadcast MUST have a unique namespace. It is
RECOMMENDED that the last tuple of the track namespace contain a
broadcast timestamp to ensure uniqueness.
Within the namespace the publisher offers media tracks named videoX
and audioX, where X is an integer starting at 0 and increasing by 1
for each additional track of a given type.
For example, if the publisher issues 2 audio tracks and 1 video
track, the track names available will be video0, audio0, and audio1.
The subscriber will consider all of those tracks belonging to the
same namespace as part of the same synchronization group (timestamps
aligned to the same timeline).
2.2. Mapping Tracks to MoQT Object Model
For the video track, the publisher begins a new group at the start of
each IDR (so object 0 will be always an IDR Keyframe), and each group
contains a single subgroup. Each object has the format described in
Section 2.4.
For the audio track, the publisher begins a new group with each audio
object, and each group contains a single subgroup. Each object has
the format described in Section 2.4.
TODO: Datagram forwarding preference could be used, but has problems
if audio frame does not fit in a single UDP payload.
2.3. Timestamps
To avoid using fractional numbers and having to deal with rounding
errors, timestamps will be expressed with two integers:
* timestamp numerator (ex: PTS, DTS, duration)
* timebase
To convert a timestamp into seconds you just need to: timestamp(s) =
timestamp numerator / timebase
_Example:_
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PTS = 11, timebase = 30
PTS(s) = 11/30 = 0.366666
2.4. Object Format
All objects this protocol have the following format.
{
Media Type (i)
Media payload (..)
}
Figure 1: MOQT Media object
* Media Type: Indicates what kind of media payload will follow.
+======+=============================+
| Code | Value |
+======+=============================+
| 0x0 | Video H264 in AVCC with WCP |
+------+-----------------------------+
| 0x1 | Audio Opus bitstream |
+------+-----------------------------+
Table 1: Media Types
* Media payload: Media type specific payload
3. Video H264 in AVCC with WCP Payload Format
{
Seq ID (i)
PTS Timestamp (i)
DTS Timestamp (i)
Timebase (i)
Duration (i)
Wall Clock (i)
Metadata Size (i)
Metadata (..)
Payload (..)
}
Figure 2: MOQT Media video h264 WCP
* Seq ID: Monotonically increasing counter for this media track.
* PTS Timestamp: Presentation timestamp in timebase.
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TODO: Varint does NOT accept easily negative values, so it could be
challenging to encode at start (priming).
* DTS Timestamp: Display timestamp in timebase. If B frames are not
used, the encoder SHOULD set this to the same value as PTS.
TODO: Varint does NOT accept easily negative values, so it could be
challenging to encode at start (priming).
* Timebase: Denominator used to calculate PTS, DTS, and Duration.
* Duration: Duration of Payload in timebase. It will be 0 if not
set.
* Wall Clock: Epoch time in ms when this frame started being
captured. It will be 0 if not set.
* Metadata Size: Size in bytes of the metadata section. It will be
0 when no metadata is present.
* Metadata: Extra data needed to decode this stream. This will be
AVCDecoderConfigurationRecord as described in [ISO14496] section
5.3.3.1, with field lengthSizeMinusOne = 3 (So length = 4). If
any other size length is indicated (in
AVCDecoderConfigurationRecord), the receiver SHOULD close the
session with a Protocol Violation error. Any change in encoding
parameters MUST send a new AVCDecoderConfigurationRecord
* Payload: H264 with bitstream AVC1 format as described in
[ISO14496] section 5.3. Using 4 bytes size field length.
4. Audio Opus bitstream Payload Format
{
Seq ID (i)
PTS Timestamp (i)
Timebase (i)
Sample Freq (i)
Num Channels (i)
Duration (i)
Wall Clock (i)
Payload (..)
}
Figure 3: MOQT Media audio Opus WCP
* Seq Id: Monotonically increasing counter for this media track.
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* PTS Timestamp: Indicates PTS in timebase.
TODO: Varint does NOT accept easily negative, so it could be
challenging to encode at start (priming).
* Timebase: Denominator used to calculate PTS and Duration.
* Sample Freq: Sample frequency used in the original signal (before
encoding).
* Num Channels: Number of channels in the original signal (before
encoding).
* Duration: Duration of Payload in timebase. It will be 0 if not
set.
* Wall Clock: Epoch time in ms when this frame started being
captured. It will be 0 if not set.
* Payload: Opus packets, as described in [RFC6716] - section 3
5. Conventions and Definitions
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.
6. Security Considerations
TODO Security
7. IANA Considerations
This document has no IANA actions.
8. References
8.1. Normative References
[ISO14496] ISO, "Carriage of network abstraction layer (NAL) unit
structured video in the ISO base media file format", 2019,
<https://www.iso.org/standard/74429.html>.
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[MOQT] Curley, L., Pugin, K., Nandakumar, S., Vasiliev, V., and
I. Swett, "Media over QUIC Transport", Work in Progress,
Internet-Draft, draft-ietf-moq-transport-07, 21 October
2024, <https://datatracker.ietf.org/doc/html/draft-ietf-
moq-transport-07>.
[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/rfc/rfc2119>.
[RFC6716] Valin, JM., Vos, K., and T. Terriberry, "Definition of the
Opus Audio Codec", RFC 6716, DOI 10.17487/RFC6716,
September 2012, <https://www.rfc-editor.org/rfc/rfc6716>.
[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/rfc/rfc8174>.
8.2. Informative References
[LOC] Zanaty, M., Nandakumar, S., and P. Thatcher, "Low Overhead
Media Container", Work in Progress, Internet-Draft, draft-
mzanaty-moq-loc-03, 4 March 2024,
<https://datatracker.ietf.org/doc/html/draft-mzanaty-moq-
loc-03>.
Acknowledgments
TODO acknowledge.
Authors' Addresses
Jordi Cenzano-Ferret
Meta
Email: jcenzano@meta.com
Alan Frindell
Meta
Email: afrind@meta.com
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