[Matroska-devel] requesting "AvgTimePerFrame" or "FieldRate" header field

madshi madshi at gmail.com
Sat Dec 15 22:10:25 CET 2012


> However, I'm thinking of situations in which there are gaps in the
> playback, e.g. due to outages in DVB-T reception. In such cases
> several frames could be missing, and of course there's no reason
> not to display anything during those missing frames. Instead the
> last frame available should be shown, of course. Therefore I'd like
> to keep the "Default".

>From my point of view, gaps don't matter. This new information field isn't
really going to be used "actively" during playback. That's what the
container timestamps are for. The only purpose of the new field is to allow
the renderer to make proper decisions at the *start* of playback. E.g.
which refresh rate to switch to, whether to activate deinterlacing, whether
to activate frame interpolation, choosing specific rendering/presentation
modes, things like that. Those are all decisions that are made at the start
of playback. Once playback has started, the new information field has no
real practical purpose, anymore, I think.

I consider the meaning of this field to simply signal which underlying
"clock" the video will be running at. When there are gaps, there will be a
few "clock beats" without new/different content, but that doesn't affect
the clock speed at all.

Anyway, I'm ok with "Default" in the name, just thinking that it's somewhat
superfluous.

> Alright, so we have a working proposal, I'd say. I'll write this up as
> a new email and hope Steve will chime in on it.

Great!

Best regards, Mathias.


2012/12/15 Moritz Bunkus <moritz at bunkus.org>

> Hey,
>
> On Sat, Dec 15, 2012 at 8:08 PM, madshi <madshi at gmail.com> wrote:
>
> > I understand what you mean. However, I think for true VFR content this
> field
> > should not be written at all, or set to 0. An "average" field rate
> > information for VFR content isn't really useful.
>
> Point taken, and I wasn't leaning towards "Average" anymore anyway.
> However, I'm thinking of situations in which there are gaps in the
> playback, e.g. due to outages in DVB-T reception. In such cases
> several frames could be missing, and of course there's no reason not
> to display anything during those missing frames. Instead the last
> frame available should be shown, of course. Therefore I'd like to keep
> the "Default".
>
> > Then let's be extra precise:
>
> Definitely.
>
> Alright, so we have a working proposal, I'd say. I'll write this up as
> a new email and hope Steve will chime in on it.
>
> Kind regards,
> mosu
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