Synchronization and Timing Issues in the Broadcast Environment. Ralf Herrmann Application Engineer

Transcription

1 Synchronization and Timing Issues in the Broadcast Environment Ralf Herrmann Application Engineer

2 SD/HD Grundlagen Ortsauflösung höheres Pixelraster: - Schärferer Bildeindruck - mehr Details 2

3 SD/HD Grundlagen Vertikal-zeitliche Auflösung Progressiv: Volle vertikale Auflösung pro Abtastzeitpunkt Interlace: Halbe vertikale Auflösung pro Abtastzeitpunkt (alternierend) 3

4 What Happens When Signals are Incorrectly Timed? Misaligned image Vertically or horizontally Commonly called screen tearing Incorrect color burst Flashes of color or unlocked color burst 4

5 Incorrectly Timed Composite Analog Video 5

6 Analog Video Synchronization Synchronization requires three basic parameters to match a reference Vertical Sync = Field Timing Horizontal Sync = Line Timing Color Sync = Subcarrier Timing 6

7 Composite Analog Video (PAL) Peak White 700 mv Horizontal Blanking Interval Active Picture Blanking Level 0 mv Sync 30 mv 7 Horizontal Sync Pulse Color Burst

8 PAL Horizontal Blanking 8

9 Vertical Interval Vertical Blanking Vertical Sync Pre-Equalizing Pulses Post Equalizing Pulses 9

10 SD 625 Vertical Blanking 10

11 HD Analog Horizontal Timing HD Tri-Level Sync Signal Fast rise times provide accurate timing edges Tri-level period much shorter than analog black burst 11

12 HD Analog Vertical Timing 12

13 Analog Video Sync Black Burst versus Tri-Level Sync Why Tri Level Sync? HD has faster rise/fall times Easier extraction of simplified field pulses O H Defined on rising edge of Tri-level sync 0v easier defined than 50% slice point of -300mv Improves jitter performance and sync separation Black Burst High Frequency subcarrier signal Known methods of extraction Known methods of multiply to other rates Used throughout facility 13

14 Digital Video SDI Test Pattern and SDI Black Reference SDI Test Pattern Various test patterns for different tests Color Bars Multiburst test signals (visual check of SDI monitors) SDI matrix / pathological signal (SDI stress test pattern) SDI Black Reference no video content (black picture) Start / End of Active Video used for synchronization might include ANC data like embedded audio with / without muted audio channels or ANC Time Code 14

15 HANC Digital Video ANC Data Areas VANC 15

16 (3FFh) Cb (000h) Y (000h) Cr (XYZh) Y (3FFh) Cb (000h) Y (000h) Cr (XYZh) Y Cb 0 Y 0 Cr 1 Y 1 SMPTE 259 (SD) Digital Horizontal Line Last active picture sample First active picture sample E A V 0mV O H Analog Bi-level Sync 300mV COMPONENT: Active line digitized, EAV/SAV added S A V XYZ Word Conveys Start/End of Line (H), Vertical Blanking (V), and Field (F) 16

17 (3FFh) C (3FFh) Y (000h) C (000h) Y (000h) C (000h) Y (XYZh) C (XYZh) Y LN0 C LN0 Y LN1 C LN1 Y CRC0 C CRC0 Y CRC1 C CRC1 Y (3FFh) C (3FFh) Y (000h) C (000h) Y (000h) C (000h) Y (XYZh) C (XYZh) Y Cb 0 Y 0 Cr 1 Y 1 SMPTE 292 (HD) Digital Horizontal Line Last active picture sample First active picture sample E A V 0mV 300mV O H +300mV Analog Tri-level Sync COMPONENT: Active line digitized, EAV/SAV added S A V XYZ Word Conveys Start/End of Line (H), Vertical Blanking (V), and Field (F) 17

18 Time Code Defined in SMPTE 12M-1 and 12M-2 Actually counts frames in a video sequence, not necessarily real-time E.g. 08:10:12.20 is 8 hours, 10 minutes, 12 seconds, 20 frames time code can be synchronized to the GPS signal (for real-time) Time Code formats: LTC (Longitudinal Time Code): Discrete signal, independent of video VITC (Vertical Interval Time Code): Located in the active line portion within the vertical blanking interval of an analog composite signal (SD) D-VITC (Digitized Vertical Interval Time Code): VITC on SDI ATC (Ancillary Time Code): ANC LTC or ANC VITC on SDI LTC VITC ATC 18

19 SPG8000 Master Sync / Clock Reference Generator Master sync pulse generator with multiple video reference outputs Master clock generator with multiple timecode outputs Optional GPS-based synchronization Optional SD/HD/3G test signal generation (plus embedded audio) Optional AES audio tones and DARS outputs Optional backup power supply Remote configuration with web-based interface, and remote management with SNMP 19

20 System Architecture Multiple Video Reference Outputs 20

21 Timing Delay Delay is a function of type of cable and the length of cable Additional delay can be introduced by routers and other inline equipment Time nsec Length of RG-59 feet Length of 8281 feet

22 SPG8000 Stay Genlock Provides Stability No Synchronization Shock on momentary loss of reference input With Go Internal Frequency, frequency mismatch appears as rotating colorburst vector on the vectorscope display and moving circle on the timing display With Stay Current Frequency, the SPG8000/TG8000 maintains the previous frequency and the vector 22

23 SPG8000 Stay Genlock Keeps Output Signals Clean Generate a noisy ( 30dB) black burst reference input SPG8000/TG8000 can still genlock to that noisy input, and also generate clean black burst outputs Noisy black burst on genlock input Clean black burst on output 23

24 ECO80x0 Automatic Changeover Unit 24

25 ECO80x0 Automatic Changeover Unit Modular architecture ECO8000: 3, 6, or 9 channels (standard BNC connectors) ECO8020: 5, 10, 15 or 20 channels (high density BNC connectors) Electronic switching Fast switching speed for near glitchless switch on black burst 50 MHz bandwidth limit cannot use for SDI test signals Change Over loses all power, keeps the current input switched to output Relay only Slight glitch (~2ms) on outputs when relay is switched > 3 Ghz bandwidth, suitable for SDI up to 3G and almost all other signal types (cannot use for 5V word clock) LTC change over support (up to 4 channels) 25

26 SPG ECO80x0 Primary SPG + Backup SPG with automatic changeover for highreliability applications Dual power supplies for high uptime Alarms and status monitoring via SNMP and GPI 26

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