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

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."
>

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.