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Audio For PBS BROADCAST. Lip Sync. Errors Can Hide Below Threshold. WGBH Public Television Quality Workshop. Scenario #1 Show: -1 frame, looks OK Station: -1 frame, looks OK Broadcast Show: -2 frames, looks bad Solution: All sync must be correct (not just look it). Errors Can Cancel.
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Errors Can Hide Below Threshold WGBH Public Television Quality Workshop • Scenario #1 • Show: -1 frame, looks OK • Station: -1 frame, looks OK • Broadcast Show: -2 frames, looks bad • Solution: All sync must becorrect (not just look it)
Errors Can Cancel WGBH Public Television Quality Workshop • Scenario #2 • Show: -3 frames • Station: +3 frames • Broadcast Show: 0 frames, looks good • But two wrongs don’t make a right! • Good shows will look bad on this station! • Solution: All sync must becorrect
Errors Can Drift WGBH Public Television Quality Workshop • Scenario #3 • Broadcast Now: Good • Broadcast Later: Bad • Solution: Be Careful! Change Channels! • Millions of commercial and consumer MPEG decoders drift!
Error Perception Can Drift WGBH Public Television Quality Workshop • Scenario #4 • Sync Now: looks good • Same Sync Later: looks bad • Solution: Patience • Need tight shots of people talking • Some people talk out of sync! • Stare at sync long enough, you will start seeing things!
Production Tips WGBH Public Television Quality Workshop • Delay audio with every video delay • Framesyncs • Switcher effects • LCD & Plasma Displays! • Don’t trust your ears • TEST!
Station Tips WGBH Public Television Quality Workshop • Align sync at every point • Framesyncs & processors • MPEG & ATSC encoder settings • Surprises • Don’t trust your ears • TEST!
Test Tools WGBH Public Television Quality Workshop • Edit Suites and QC Stations • syncheck.com • TV Stations • ID with 1 frame dot and beep, then non-linear editor • Normal programming with Miranda or Evertz solutions
Consumer Tips WGBH Public Television Quality Workshop • LCD & Plasma TV's • Internal decoder should be OK • Separate decoder & audio systems require offset! • MPEG decoders • Try changing channels
Industry Progress • Early Confusion • Subsequent Conflict & Loudness Wars • Recent Consensus: ATSC A85! • www.atsc.org/cms/standards/a_85-2009.pdf WGBH Public Television Quality Workshop
Production Tips WGBH Public Television Quality Workshop • Buy an LKFS meter (BS.1770) • Your mix engineers will like it! • No money? • Dialog peaks at -10 dBFS works pretty well • Produce content to -24 LKFS • Average over entire show, ± 2 dB • Dramatic moments can still be ±10 dB!
Station Tips WGBH Public Television Quality Workshop Set plant for unity gain Set encoder dialnorm to -24 Get an LKFS meter (BS.1770) Measure day-long compliance with -24 LKFS Apply processing if needed Compare local stations and share
5.1 Surround • PBS Submission Requirement • Effective March 2011! • Up-mix OR actual 5.1 production • Requires Dolby E • Caution • Calibrate your LFE monitoring per ATSC A85 • Insure downmix is compatible • Most stations cannot afford to broadcast 5.1 WGBH Public Television Quality Workshop