Time Format for a New Label Why PTP?

Time Labels Have Multiple Uses No one label format is optimal for all use cases No one time format is optimal for all use cases No one epoch is optimal for all use cases The design essential is that the chosen format support all known use cases (via use-case applications where necessary) Where there are multiple use cases, good engineering requires that the design be as universal as possible, and not “build in” assumptions about specific use cases. The label design should be independent of any specific transport

The “Digital Birth Certificate” Concept first advanced at Hollywood reach-out meeting in 2010 Comprises … Time value Source ID Media-unit counter(s) Conveys all essential information for captured content It should be possible to add additional fields (such as SMPTE 12) as needed for later processes (post production, playout preparation, etc.)

Simplicity is a Virtue Attempts to address specific user requirements and human-interface issues add complexity to the label, and may reduce its universality Many listed requirements (such as Daily Jam) have local variations and parameters. These are best addressed by user applications Calculation is inexpensive. A single time format such as PTP can easily be rendered in any required form such as HH:MM:SS:FF

PTP is the Natural Choice As SMPTE experts have made very clear, conversion among time formats is complex, maybe even ambiguous, and difficult to solve in the general case SMPTE has adopted PTP for 2059 and 2110 series documents These, together with the time label are fundamental; SMPTE should NOT permit any complexity of time conversion across there Standards Time-format conversion routines for application at the point of use already exist and are easy to implement

Some Objections to PTP Needs to work for absolute and non-absolute time Any non-absolute time may be derived from the media-unit count EDLs etc. need to work in media units Most edit systems define their own internal indexing; a media-unit count is provided in the proposed label You don't have to constrain every time label to use the same time unit That’s just another way of de-standardizing the label (creating multiple labels) Program time does not depend on absolute acquisition time Program time does not even need a label; it may be created from the required start time and a local media-unit count (just like striping)

Summary The proposed Time Label, based on the “Digital Birth Certificate” definition, provides support for all known use cases, including variable frame rate, time lapse, etc. etc. It is simple, but extensible, and is not compromised by assumptions about specific use cases Use of PTP aligns with other core SMPTE Standards SMPTE 12 was adopted in many industries; use of IEEE 1588 will encourage similar widespread acceptance of the new label Conversion from PTP is well-documented and simple to implement