Andreashildebrand

ST2110 & AES67 Commonalities & Constraints - Andreas Hildebrand ALC NetworX, Munich

A. Hildebrand: ST2110 & AES67 - Commonalities & Constraints

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Andreas Hildebrand, RAVENNA Technology Evangelist • more than 25 years in the professional audio / broadcasting industry • graduate diploma in computer science • R&D, project & product management experience • member of AES67 TG and ST2110 DG ALC NetworX GmbH, Munich / Germany • established 2008 • R&D center • developing & promoting RAVENNA • Partnerships with > 40 manufacturers RAVENNA • IP media networking technology • designed to meet requirements of professional audio / broadcasting applications • open technology approach, license-free • fully AES67-compliant (built-in) #2

A. Hildebrand: ST2110 & AES67 - Commonalities & Constraints

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SMPTE 2110

SDI

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A. Hildebrand: ST2110 & AES67 - Commonalities & Constraints

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SMPTE 2110 (32NF-60 SVIP - Studio Video over IP) Document structure:

• 2110-10: System Timing & Definitions  defines transport layer and synchronization (SMPTE2059, clocks, RTP, SDP etc.)

• 2110-20: Uncompressed Active Video  defines payload format for raw video (RFC4175, RTP, SDP, constraints) • 2110-21: Timing Model for Uncompressed Active Video  defines timing model for senders and receivers (traffic shaping requirements)

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A. Hildebrand: ST2110 & AES67 - Commonalities & Constraints

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SMPTE 2110 (32NF-60 SVIP - Studio Video over IP) Document structure:

• 2110-30: PCM Digital Audio  defines payload format for linear audio (AES67, constraints) • 2110-31: AES3 Transparent Transport  defines payload format for non-linear audio (RAVENNA AM824)

• 2110-40: Ancillary Data  defines RTP payload format for SDI ancillary data (new IETF draft) • 2110-50: Interoperation of ST 2022-6 Streams  what it says… (VSF TR-04) #5

A. Hildebrand: ST2110 & AES67 - Commonalities & Constraints

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AES67-2015 Standard for Audio Applications of Networks: High-performance Streaming Audioover-IP Interoperability

AES67 #6

A. Hildebrand: ST2110 & AES67 - Commonalities & Constraints

published on September, 11th, 2013

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Scope: •

Interoperability guidelines for professional, low‐latency audio over campus and local area IP networks using existing protocols wherever possible.

•

Excludes:     

Non‐IP networking Low‐bandwidth media Data compression Low‐performance WANs and public Internet Video (should provide good basis for follow‐on video project)

Goal: •

Technology providers may choose to implement interoperability as a special mode, or transition to it as their native mode

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A. Hildebrand: ST2110 & AES67 - Commonalities & Constraints

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AES67

X

Dante

X

WheatNet

RAVENNA

Livewire

Q-LAN

X

X

IP A. Hildebrand: ST2110 & AES67 - Commonalities & Constraints

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AES67 – the “O negative” of audio networking ACIP AES67 AES67

AES67

A. Hildebrand: ST2110 & AES67 - Commonalities & Constraints

RAVENNA

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AES67 technology components: •

Synchronization: IEEE 1588-2008, default profile (media profile suggested)

•

local media clock generation

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A. Hildebrand: ST2110 & AES67 - Commonalities & Constraints

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Synchronization & media clocks •

All nodes are running local clocks

•

Local clocks are precisely synchronized to a common wall clock via PTP

•

Media clocks are generated locally from synchronized local clock

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A. Hildebrand: ST2110 & AES67 - Commonalities & Constraints

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Synchronization & media clocks Master Clock

PTP Slave Clocks (nodes)

Media Clocks

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A. Hildebrand: ST2110 & AES67 - Commonalities & Constraints

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Synchronization & media clocks •

All nodes are running local clocks

•

Local clocks are precisely synchronized to a common wall clock via PTP

•

Media clocks are generated locally from synchronized local clock

•

Generation of any desired media clock (sample rate) possible

•

Concurrent operation of different media clocks possible

•

Phase accuracy of AES 11 (± 5% of sample period) achievable by deployment of PTP-aware switches (BC or TC)

•

Synchronization across facilities possible by reference to absolute time (TAI)

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A. Hildebrand: ST2110 & AES67 - Commonalities & Constraints

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Synchronization & media clocks •

3 type of clocks in the system: •

Wall clock - provided by Grandmaster

 local copy of the wall clock in each node

•

•

Media clock – derived from the local clock (i.e. 48 kHz for audio, 90 kHz for video)

•

RTP clock – derived from the media clock

Essence data (audio samples or video frames) is related to the media clock upon intake - essentially receiving a generation “time stamp” with respect to the media clock

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A. Hildebrand: ST2110 & AES67 - Commonalities & Constraints

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Synchronization & media clocks

Wall clock PTP

(PTP Grandmaster)

(copy)

• Relations T and R are established on node start-up • Relation S is established on stream start-up • S may be random to defeat cryptotext attacks • This offset will be constant throughout the stream’s lifetime

(copy)

Sender

Receiver

Local clock

T

PTP

Local clock

Stream clock

S

R SDP

Media clock

Media clock

Stream data

• The offset will be conveyed via SDP (a=mediaclk:direct=<offset>) – “0” in ST2110 # 15

A. Hildebrand: ST2110 & AES67 - Commonalities & Constraints

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Synchronization & media clocks •

3 type of clocks in the system: •

Wall clock - provided by Grandmaster •

A local copy of the wall clock in each node

•

Media clock – derived from local clock (i.e. 48 kHz for audio, 90 kHz for video)

•

RTP clock – derived from the media clock

•

Essence data (audio samples or video frames) is related to the media clock upon intake (essentially receiving a generation “time stamp” with respect to the wall clock)

•

Fixed / determinable latency by configuring a suitable link offset (“playout delay”)

•

Inter-stream alignment by comparing and relating the time stamps of individual essence data

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A. Hildebrand: ST2110 & AES67 - Commonalities & Constraints

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AES67 technology components: •

Synchronization: IEEE 1588-2008, default profile (media profile suggested)

•

local media clock generation

•

Network: IPv4 (IPv6), unicast / multicast & IGMPv2

•

Transport: RTP/AVP (RFC 3550 & 3551) / UDP / IP

•

Encoding: 16 / 24 bit linear, 48 (44.1 / 96) kHz, channel count: 1..8

•

Packet Setup: 48 samples (6 / 12 / 16 / 192), max. payload size: 1440 bytes

•

Quality of service: DiffServ w/ 3 suggested traffic classes (DSCP)

•

Connection management: SDP, IGMP (multicast), SIP (unicast)

•

Discovery: excluded, but several possibilities mentioned (i.e. ZeroConf, SAP and others)

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A. Hildebrand: ST2110 & AES67 - Commonalities & Constraints

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SMPTE 2110 (32NF-60 SVIP - Studio Video over IP) Constraints of 2110-10 & -30 w/ respect to AES67 - Synchronisation & Timing -

• PTP:  support of SMPTE 2059-2 required  message rate according to AES-R16-2016 (AES67 PTP Media profile)  defaultDS.slaveOnly=true for devices not capable of entering PTP master state  a=ts-refclk:ptp=traceable and a=tsrefclkts-refclk:localmac=<mac_addr> allowed

• RTP clock: offset= 0 w/ respect to media clock / network clock  a=mediaclk:direct=0

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A. Hildebrand: ST2110 & AES67 - Commonalities & Constraints

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SMPTE 2110 (32NF-60 SVIP - Studio Video over IP) Constraints of 2110-10 & -30 w/ respect to AES67 - Protocols -

• Support of RTCP not required (but must be tolerated) • Support of SIP (or any other connection management protocol) not required • Redundancy: SMPTE 2022-7  no identical IP source and destination addresses • Optional channel assignment map (SDP)  a=fmtp:<payload type> channel-order=<convention>.<order>  Example: a=fmtp:101 channel-order=SMPTE2110.(51,ST)

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A. Hildebrand: ST2110 & AES67 - Commonalities & Constraints

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SMPTE 2110 (32NF-60 SVIP - Studio Video over IP) Constraints of 2110-30 w/ respect to AES67:

• 4 conformance levels: Level

Supported by the Receiver

A

Reception of 48 kHz streams with 1 to 8 audio channels at packet times of 1 ms

B

Level A + 1 to 8 channels at packet times of 125 µs

C

Level A + 1 to 64 channels at packet times of 125 µs

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A. Hildebrand: ST2110 & AES67 - Commonalities & Constraints

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SMPTE 2110 (32NF-60 SVIP - Studio Video over IP) Constraints of 2110-30 w/ respect to AES67:

â&#x20AC;˘ 4 conformance levels: Level

Supported by the Receiver

D

Level C + Reception of 96 kHz streams with 1 to 4 channels at packet times of 1 ms and 1 to 32 channels at packet times of 125 Âľs

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A. Hildebrand: ST2110 & AES67 - Commonalities & Constraints

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Contact information:

Andreas Hildebrand Technology Evangelist ravenna@alcnetworx.de

ALC NetworX GmbH Am Loferfeld 58 81249 Munich Germany

www.ravenna-network.com A. Hildebrand: ST2110 & AES67 - Commonalities & Constraints

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