Re: ISSUE-151 Clarify syncbase in SMPTE continuous mode - Draft Change Applied

On Mon, May 28, 2012 at 8:29 AM, Glenn Adams <glenn@skynav.com> wrote:

>
> On Mon, May 28, 2012 at 7:35 AM, Andreas Tai <tai@irt.de> wrote:
>
>> **
>> Thanks, Glenn for clarification. That´s the same how I understand it.
>>
>> I would therefore propose the following change in chapter 10.4 Time
>> Intervals:
>>
>> => 4th bullet point
>>
>> Now:
>> "If the governing time mode is media or smpte with mode continuous, then
>> time expressions must be interpreted as equivalent to offset based timing
>> in [SMIL 2.1], namely, as offsets from an implicit syncbase."
>>
>> Change Proposal:
>> "If the governing time mode is media, then time expressions must be
>> interpreted as equivalent to offset based timing in [SMIL 2.1], namely, as
>> offsets from an implicit syncbase."
>>
>
In the most recent ED, this text has been updated to refer to the new
Appendix N suggested interpretations of time expression semantics.


>
> The current text is correct since for smpte time base with continuous
> marker mode, time expressions are in fact equivalent to offset based
> timing, where the start of the implicit syncbase for tt:tt is 00:00:00.0.
> However, given the following bullet in 10.4 (about smpte discontinuous
> begin equivalent to marker values), I can see how one may   read 10.4 as
> saying that smpte continuous mode does not entail marker values. The
> intention is that smpte continuous be marker values that are equivalent to
> offset based timing (due to satisfaction of continuity and monotonicity).
> Perhaps breaking out smpte continuous into its own bullet would be the way
> to better express this intention.
>
>
>
>
>