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Reference distribution. SMPTE proposal. (View the Notes pane to see comments by Rob Silfvast and Willem-Jan Dirks). Introduction. For background on the approach supported within SMPTE: Google search [“Paul Briscoe” and “the new genlock”].
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Reference distribution SMPTE proposal (View the Notes pane to see comments by Rob Silfvast and Willem-Jan Dirks)
Introduction For background on the approach supported within SMPTE: Google search [“Paul Briscoe” and “the new genlock”] • First years there will be a mixed environment. Feedback of customers is to keep a long transition period in mind. • Traditional gen-lock sources will source the reference in this mixed environment. • Receiving signals that some “Big players” in the broadcast domain are aiming for the SMPTE 33TS reference solution. • We don’t want to inherit the current situation where references need to be tuned for different sources.
Pro: • Doesn’t increase bandwidth usage. Calculations are made in each endpoint using the timestamps already distributed by the clock master. Only a single control packet to tell the endpoint which reference to take. • SMPTE defined standard which is respected in the Video Broadcast (VB) domain. • Ready for future reference standards. • Multiple reference standards distribution in a single network (not used today in VB).
Cons: • Calculations are not straight forward. • No backup master as when using streams, this could result in a “reference jump” when switching from Master to a new Master. • A relation to TAI (via GPS) is needed for synchronizing “Traditional” infrastructures to an AVB network.
To Do before deciding: • Investigating the “cost” of a SMPTE implementation • Most complex implementation is for the 59,94 reference, since this has a 1,001 relation to a second. Each 1001 second there is an aligned frame. • Find solution for “ref jump” when master changes • Automatic master switching is under discussion for broadcast, since customers are afraid of this principle.