Re: Time expressions when ttp:timeBase="media"

On Wed, Jan 30, 2013 at 10:38 AM, Jason Livingston <jason@cpcweb.com> wrote:

>  I still have a question about the starting time of the media object
> though.  Does the media object time always start at 0 seconds, or can "a
> coordinate in the media object's time line" be interpreted to mean that the
> media object could start at a non-zero time?  (E.g. if the media object has
> a time code track which starts at 01:00:00:00)
>
> ** **
>
> Personally I would like the answer to be "the media object always starts
> at 0 seconds," but I am not certain if that's the only possible
> interpretation of the spec.
>

The TTML media timebase value of zero corresponds to the beginning of the
external time interval. If the external time interval is derived from a
related media object, then that beginning is implied from the beginning of
that related media object.

I agree that this could be made more clear in the spec, so I've filled
https://www.w3.org/AudioVideo/TT/tracker/issues/200 to that effect