Aligning Streams in ST 2110 to Manage Lip Sync

Presenters : Leigh Whitcomb - Imagine Communications

Year : 2019

dlp_document_download : C U R A T E D B Y I P S H O W C A S E T H E AT E R AT N A B – A P R I L 8 -11 , 2 01 9 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 2110 GW 2110 -20 video 2110 -30 audio 2110 -40 ancillary Network 2110 -20 video 2110 -30 audio 2110 -40 ancillary 2110 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 2110 GW 2110 -20 video 2110 -30 audio 2110 -40 ancillary Network 2110 -20 video 2110 -30 audio 2110 -40 ancillary 2110 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 3000 6000 9000 12000 15000 18000 21000 24000 27000 30000 33000 36000 39000 42000 45000 48000 51000 54000 57000 60000 63000 66000 69000 72000 75000 78000 81000 84000 87000 90000 93000 96000 99000 RTP VAlue 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 I P S H O W C A S E T H E AT E R AT N A B – A P R I L 8 -11 , 2 01 9 Thank You Leigh Whitcomb, Imagine Communications Leigh.Whitcomb@imaginecommunications.com