Timing and Sync SMPTE · PDF fileEpoch Aware Epoch Aware Epoch Aware Slave Device Master...
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Transcript of Timing and Sync SMPTE · PDF fileEpoch Aware Epoch Aware Epoch Aware Slave Device Master...
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Paul Briscoe Manager, Strategic Engineering, Harris Broadcast
Network-‐Based Timing and Synchroniza�on
“Genlock in the Cloud”
IEEE Mee�ngs, Victoria, BC. May 14th, 2013
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Sync and Timing in Media
Why do we synchronize things? Video Switching, Mixing Use Genlock – Black Burst or TLS
What about digital audio? DARS (AES3 / AES11)
What about time? Timecode SMPTE ST-12
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Synchroniza�on in Media
3
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System Synchroniza�on
4
Studio A
Studio B Edit 1
OB Truck
Edit 2 Graphics
MCR Feeds
Master Generators
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System Synchroniza�on
5
Studio A
Studio B Edit 1
OB Truck
Edit 2 Graphics
MCR Feeds
Master Generators
Black, DARS, Timecode
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System Synchroniza�on
6
Studio A
Studio B Edit 1
OB Truck
Edit 2 Graphics
MCR Feeds
Master Generators
Black, DARS, Timecode
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Distribu�on System
7
Master SPG
Autochangeover
First Floor Second Floor Third Floor Fourth Floor Fifth Floor Sixth Floor Seventh Floor
NW Quad SW Quad SE Quad SW Quad
STD 12 STD 13 STD 14 STD 15 STD 16
Master Control / Central Equipment Fourth Floor SW Quad STD 14
Studio Gear
Studio Gear
Slave SPG
Master SPG
Studio Gear
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Distribu�on System Layers
8
Master SPG
Autochangeover
First Floor Second Floor Third Floor Fourth Floor Fifth Floor Sixth Floor Seventh Floor
NW Quad SW Quad SE Quad SW Quad
STD 12 STD 13 STD 14 STD 15 STD 16
Master Control / Central Equipment Fourth Floor SW Quad STD 14
Studio Gear
Studio Gear
Slave SPG
Master SPG
Studio Gear
Master SPG
Autochangeover
Slave SPG
Master SPG
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What do References Deliver?
Frequency Different for each signal type used Varying degrees of tolerance
Phase Known phase references
VSync, HSync - ST318 BlackBurst Audio block, frame - AES3 /
AES11 Time of Day - ST12 Timecode Date - ST309
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Genera�ng Signals
10
Logic state machines generate signals from a clock (timebase)
Operate at framerate modulus Generate the same thing over and over
and over Known rate, but arbitrary phase =
asynchronous This is every piece of free-running gear
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Genera�ng Signals -‐ Freerunning
11
Local high-precision oscillator generates clock SMPTE Frequencies
Logic state machines generate signals
Free-running
TCXO
Signal Generator SDI
Clock
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Genera�ng Locked Signals
12
Frequency Lock – clock for signal generator
Phase Lock – vertical (and horizontal) alignment Achieved by resetting the generator to an
anchor Vertical Sync is a natural anchor for video
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Genera�ng Locked Signals
13
Sync Separator extracts H and V H drives PLL to generate locked timebase V resets signal generator to known phase H and V knobs adjust timing relative to
reference
Logic
Signal Generator
Phase-locked loop
Clock
Sync Separator
Black Burst
SDI H
V
TCXO
V Reset
H V
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Sync and Timing Systems Today
So what’s the problem with that? Ancient technologies (from a simpler
time) Mix of analog and digital-ish signals Serious modern functional limitations
Don’t support > 60 fps, VFR BlackBurst ≠ HDTV Require multiple distributions CAPEX, OPEX nailed down architectures
It’s 2013, there must be a better way!
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IP Networks
15
Touch most equipment today Easy to deploy, modify Remotely / centrally managed Security provisions
The new core infrastructure for media Might be a good way to distribute references
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New Opportunity
16
Studio A
Studio B Edit 1
OB Truck
Edit 2 Graphics
MCR Feeds
Master Generators
IP Network
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Network-‐Delivered Reference Requirements
17
Deliver references over IP network Provide capability of legacy systems Deterministic behaviour Provide open platform for future
Signals (transports) Formats (essence)
Use COTS technology wherever possible
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Network Performance
18
Non-deterministic Can’t predict when things happen Traffic all shares the road Message delays are variable
Jitter! Things get lost We need a core technology that overcomes this!
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One Possible Solu�on
19
NTP Works on IP networks Deterministic Delivers time Not enough
performance millisecond-class
time accuracy
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Enter IEEE 1588 PTP
20
Network-based Precision Time Protocol Delivers precision time to many slaves Spans hundreds of years Sub-nanosecond granularity Delivered over IP network Can be globally locked Can co-exist with other traffic
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1588 Span and Granularity
21
1 Sec
ond
1 Minu
te
1 Hou
r
1 Day
1 Mon
th
1 Yea
r
1 Milli
seco
nd
1 Micr
osec
ond
1 Nan
osec
ond
SDI Video
12M Timecode
Calendar
NTP
AES Audio
Composite Video
IEEE1588
GPS Native
Nanoseconds – 32 bits (1 ns)Whole Seconds - 32 bits (~136 years)
64-bit binary time count
LSB
1 Hz(PPS)
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1588 Span and Granularity
22
1 Sec
ond
1 Minu
te
1 Hou
r
1 Day
1 Mon
th
1 Yea
r
1 Milli
seco
nd
1 Micr
osec
ond
1 Nan
osec
ond
SDI Video
12M Timecode
Calendar
NTP
AES Audio
Composite Video
IEEE1588
GPS Native
Nanoseconds – 32 bits (1 ns)Whole Seconds - 32 bits (~136 years)
64-bit binary time count
LSB
1 Hz(PPS)
Us
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Frequency from Time
23
PTP delivers time, not frequency Frequency is transferred by comparing local timekeeping to incoming “At the tone, the time….”
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Signals From Time
24
Time = signal phase Pick an Epoch (instant in time)
Some past date and time (PTP Epoch)
Define alignment of signals to that instant Can predict future phase of any signal
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Timebase Genera�on from PTP
25
PTP Slave has locked timebase
SMPTE Frequencies are cross-synthesized to required frequency Many methods Low cost High accuracy
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Anchor Genera�on from PTP
26
Signal Generator
Clock
SDI
V Reset
Local Running Time Count Live Running Time
Compare Calculate Next Ver�cal
Equal
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Full Genlock from PTP
27
Logic
Signal Generator
Cross-synthesis
Clock
SDI
TCXO
V Reset
H V
Local Running Time Count
Local Timebase Oscillator
Live Running Time
10 MHz SMPTE Frequency
Compare Calculate Next Ver�cal
Equal
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Dual-‐Mode Genlock Equipment
28
Logic
Signal Generator
Cross-synthesis
Clock
SDI
TCXO
V Reset
H VLocal Running Time Count
Local Timebase Oscillator
Live Running Time
10 MHz
Calculate Next Ver�cal
Equal
Logic
Phase-locked loop
Sync Separator
Black Burst
H
V
TCXO
Compare
P PTP
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Some Limita�ons
29
Within a system, timing is deterministic All running from same master
Between systems, timing is non-deterministic Can achieve frequency lock Phase between systems is manual That’s why we have frame
synchronizers
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Determinis�c Behaviour
30
Establish alignment of all signals at Epoch Yellow and blue represent two different
SMPTE signal types Conveyor belt is PTP timebase Signals phase (anchor) aligned at Epoch
t = 0A
B
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Determinis�c Behaviour
31
At some future time (t=X) Signals will have different phases Each can be calculated from Epoch
t = XA
B
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Determinis�c Behaviour
32
External reference turns belt (GPS) Wheel phase is
predictable between systems
Reference can be GPS, other GNSS, big PTP network
GPS(t) = XA
B
GPS
GPS(t) = XA
B
GPS
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Determinism
33
Time Counter
Time Counter
Time Counter
Timebase
Signal Generator
Signal Generator
Signal Generator
Signal Y
Signal Z
Signal XEpoch Aware
Epoch Aware
Epoch Aware
Slave Device
Master Generator
Time Transport
Can be derived from external sources
(GPS, etc.)
Signals X, Y and Z will be locked and in phase
Slave Device
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Net Result
34
Can deliver all references over IP network Can have independent systems in phase Can share other traffic on same network Control, monitoring File-based transfers Compressed streaming Soon live baseband over IP
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History of Time-‐Based References
35
1998 – Leitch (Kupnicki) develops method
Time transport over BlackBurst 1999 – SMPTE not ready to embrace
- That’s OK, we use it inside products 2007 – SMPTE / EBU establish taskforce
Leitch method modernized to use PTP 2010– Basis for SMPTE Standard work
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SMPTE Ac�vi�es
36
33TS Synchronization and Time Labeling Standardization Committee Drafting the ST 2059 Standard Suite
Includes EG and RP ST 2059-0 Overview of Standard ST-2059-1 Generation of Signals ST-2059-2 SMPTE PTP Profile
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Signal Genera�on Document
37
Specification of SMPTE Epoch Alignment for each signal of interest
References to root standards Formulae for each signal of interest
Direct derivation from time Generation of Time of Day Generation of Timecode
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SMPTE PTP Profile Document
38
SMPTE-specific performance criteria Message Rates Node Types Master Selection Alternate Time Offset
SMPTE-specific metadata Timecode Helper Data System Framerate Miscellaneous System Stuff
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SMPTE ac�vi�es
39
Working Groups 33TS-20 developing sync system
Signal Generation and Profile Work nearing completion
33TS-10 developing new Time Label Work actively underway
Includes EGs and RPs
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Thank-you! Questions?
More information? Shoot me a note Paul Briscoe [email protected]