Aligning Streams in ST 2110 or How to Manage Lip Sync · CURATED BY IP SHOWCASE THEATER AT NAB –...
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CURATED BY IP SHOWCASE THEATER AT NAB – APRIL 8-11, 2019 Aligning Streams in ST 2110 or How to Manage Lip Sync Leigh Whitcomb, SMPTE Fellow, Architect Imagine Communications
Transcript of Aligning Streams in ST 2110 or How to Manage Lip Sync · CURATED BY IP SHOWCASE THEATER AT NAB –...
C U R A T E D B Y
IP SHOWCASE THEATER AT NAB – APRIL 8-11, 2019
Aligning Streams in ST 2110 or How to Manage Lip Sync
Leigh Whitcomb, SMPTE Fellow, Architect
Imagine Communications
What Problem Are We Solving?
2
With ST 2110, Did the Problem Magically Go Away?
No
3
With ST 2110, Did the Problem Get Worse?
Yes
4
ST 2110 Has Separate Essence Flows
5
SDI
21
10
GW
2110-20 video
2110-30 audio
2110-40 ancillary
Network
2110-20 video
2110-30 audio
2110-40 ancillary 21
10
GW
SDI
6
t=0
Processing delay
Processing delay
spatial delay
RX@41ms
TX@12ms
NET
NET Processing delay
TX@50ms
Processing delay
RX@13ms TX@20ms
TX@40ms
Receiver
NET
(aud) RX@21ms
(vid) RX@51ms
13 in/ms
Receiver has to re-align the
A/V
6 slides of Doom and Gloom, Will It Get Better?
Yes
Time Stamps
7
8
t=0
Processing delay
Processing delay
spatial delay
TS=0 RX@41ms
TS=0 TX@12ms
NET
NET Processing delay
TS=0 TX@50ms
Processing delay
TS=0 RX@13ms
TS=0 TX@20ms
TS=0 TX@40ms
Receiver
NET
(aud) TS=0 RX@21ms
(vid) TS=0 RX@51ms
13 in/ms
Receiver has to re-align the
A/V
All Devices Locked Together
Network Time and
Clock
2059 Grandmaster #1
Network Time and
Clock
2059 Grandmaster #2
Ethernet Switch
Local version of
Network Time and
Clock
Media Node #1
GPS #1 GPS #2
Local version of
Network Time and
Clock
Media Node #2
Local version of
Network Time and
Clock
Media Node #3
RTP Time Stamp
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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Time Stamp | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SSRC | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
RTP Header
Link Offset -> Presentation Delay -> Reconstruction Delay
11 Source: VSF TR-03
Reconstruction Delay
• Process each stream separately
• Indirectly align
SDI
21
10
GW
2110-20 video
2110-30 audio
2110-40 ancillary
Network
2110-20 video
2110-30 audio
2110-40 ancillary 21
10
GW
SDI
RTP Timestamps
• Metadata that describes when the essence was created ‒ Can be changed independently of the essence
• Initially created from PTP/2059 time
• 32-bit rollover
• Units ‒ -20 Video: 90 KHz ticks
‒ -30 Audio: 48 KHz ticks
‒ -40 ANC: 90 KHz ticks
RTP Timestamps
0
1E+09
2E+09
3E+09
4E+09
5E+09
6E+09
7E+09
8E+09
9E+09
1E+10
0
30
00
60
00
90
00
12
00
0
15
00
0
18
00
0
21
00
0
24
00
0
27
00
0
30
00
0
33
00
0
36
00
0
39
00
0
42
00
0
45
00
0
48
00
0
51
00
0
54
00
0
57
00
0
60
00
0
63
00
0
66
00
0
69
00
0
72
00
0
75
00
0
78
00
0
81
00
0
84
00
0
87
00
0
90
00
0
93
00
0
96
00
0
99
00
0
RTP
VA
lue
PTP Time (s)
RTP Count value
Audio RTP TS Video RTP TS PTP Time
Testing
• “Dirty Hands” Workshop ‒ Feb. 18 – 22, 2019
‒ Testing newer parts of the standard and parts that were not well tested
Open Work
16
• What is the minimum Reconstruction Delay a product should support?
• Re-timestamping
Key Take Aways
• Separate essence flows requires alignment
• All devices locked together
• RTP Timestamps from PTP/2059 time
• Change RTP Timestamp without changing the Essence
• Reconstruction Delay ‒ Indirectly aligns the streams
• Open work ‒ Re-timestamping and Reconstruction Delay
C U R A T E D B Y
IP SHOWCASE THEATER AT NAB – APRIL 8-11, 2019
Thank You
Leigh Whitcomb, Imagine Communications
