[theora-dev] Timestamps...

illiminable ogg at illiminable.com
Fri May 14 17:08:46 PDT 2004



----- Original Message -----
From: "Ralph Giles" <giles at xiph.org>
To: <theora-dev at xiph.org>
Sent: Saturday, May 15, 2004 1:10 AM
Subject: Re: [theora-dev] Timestamps...

<p>> On Fri, May 14, 2004 at 04:23:53PM +0800, illiminable wrote:
>
> > The conversion of time representations is just a simple calculation...
The
> > decode the packets options is a far more complicated operation, and
either
> > requires the demux knowing how to decode itself or being able to call
the
> > decoder to figure it out. Which means processing the page... certainly
any
> > simple calculation will be far more efficient that potentially reading
and
> > processing a whole page of data.
>
> Sounds like you're arguing for real-time granulepos again.
>
No... it that would be nice, but it doesn't really matter, any granule pos
scheme is fine.

> If you know the media is 'continuous' the start time of the page is the
end-
> time of the previous page. Having an extra granulepos field on each page
> doesn't help you at all here. Is there any problem with just applying this
> abstraction to 'discontinuous' streams in DirectShow? I guess so if you
> really need per-packet start and end timestamps.
>

It does help because it means you don't have to search for a pervious page
in every logical stream. At the moment, you have to find the page you want
to start at, then seek backwards to ensure you go back far enough that you
find the previous page of every stream, in order to find the relative start
times of each stream at your desired start position.

Yes... start packet times are pretty much essential for the renderer.

Zen.

>  -r
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