Re: [MSE] Timestamp offset mechanism

Hi All,

I'm going to try to summarize what I've read on this thread to see if I
understand everyone's position

1. Eric, Steve, & Kevin all support the sourceTimestampOffset() signature
2. Mark doesn't have a strong preference either way, but is leaning towards
sourceTimestampMapping() because it is more explicit about the application
needing to know about the internal timestamps in the media segments and how
they should map to the presentation timeline.
3. The alternative nextSegmentStartTime()/clearTimestampOffset() suggestion
mentioned at the bottom of
http://lists.w3.org/Archives/Public/public-html-media/2012Jun/0095.html got
no votes
4. Duncan feels this mechanism isn't sufficient to address ad-insertion use
cases he cares about. I just started an Ad Insertion
thread<http://lists.w3.org/Archives/Public/public-html-media/2012Jul/0033.html>
to
continue the discussion. This may require adding a new feature.

Let me know if this is correct or if I've missed something.

Thanks,
Aaron


On Fri, Jun 15, 2012 at 3:40 PM, Aaron Colwell <acolwell@google.com> wrote:

> Hi,
>
> Bug 17004 <https://www.w3.org/Bugs/Public/show_bug.cgi?id=17004> proposes
> a mechanism for adjusting timestamps inside media segments. This enables
> seamlessly splicing content together that doesn't originally exist on a
> common presentation timeline. Inserting advertisements into content is the
> most straight forward use case. There has been some useful discussion in
> the bug comments, but we haven't decided on which method signature to use
> for specifying the timestamp adjustments.
>
> Here are the proposed signatures at this point:
>
> void sourceTimestampMapping(in double presentationTimestamp, in double
> segmentTimestamp)
>  -- or --
> void sourceTimestampOffset(in double timestampOffset)
>
> sourceTimestampMapping() just provides a way to say, "I want this
> timestamp in the segment to map to this presentation time."
> sourceTimestampOffset() is basically just saying, "Add this offset to any
> timestamp in the segment to get the desired presentation time."
>
> Fundamentally they do the exact same thing, but I'm looking for input on
> which option people feel more comfortable with.
>
> Which do you prefer?
> Are you ok with the semantics outlined in the bug description<https://www.w3.org/Bugs/Public/show_bug.cgi?id=17004#c0>
> ?
>
> Aaron
>
>