[FFmpeg-user] Filter documentation -- PTSs

[Paul B Mahol]

On Mon, Feb 15, 2021 at 2:23 AM Mark Filipak (ffmpeg) <markfilipak at bog.us>
wrote:

> On 02/14/2021 08:13 PM, Paul B Mahol wrote:
> > On Mon, Feb 15, 2021 at 1:46 AM Mark Filipak (ffmpeg) <
> markfilipak at bog.us>
> > wrote:
> >
> >> On 02/14/2021 07:34 PM, Paul B Mahol wrote:
> >>> On Mon, Feb 15, 2021 at 12:50 AM Mark Filipak (ffmpeg) <
> >> markfilipak at bog.us>
> >>> wrote:
> >>>
> >>>> Disclosure: Everything that follows may be wrong.
> >>>>
> >>>> I reckon that, except for a few filters, the important metric is PTS,
> >> not
> >>>> the frame #s assigned at a
> >>>> filter's input node nor its wall-clock arrival time at a filter's
> input
> >>>> node. For example,
> >>>> 'interleave' performs frame interleaves based on the PTSs of incoming
> >>>> frames -- at least, that's
> >>>> what I think.
> >>>>
> >>>> Am I correct?
> >>>>
> >>>> If so, wouldn't it be helpful if filter documentation included how it
> >>>> generates PTSs?
> >>>>
> >>>
> >>> PTS are not generated.
> >>
> >> ffmpeg -i SOURCE -vf telecine TARGET
> >>
> >> What are the PTSs of the first 5 frames at the output of the filter?
> >>
> >>
> > Interpolated by very complex formula.
>
> So, the PTSs are generated.
>
> What is the formula? Certainly it can't be anywhere nearly as complex as
> the differential equations
> and boundary conditions that control air flow through a duct of arbitrary
> shape or the air flow
> across an aircraft wing of arbitrary profile. I guess if I can handle
> those, I'll be able to handle
> the generated PTSs of a periodic series of frames, eh?
>

You need TB aka timebase too.

TB is rational.
PTS is 64bit integer.


>
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