[FFmpeg-user] Filter documentation -- PTSs

[Mark Filipak (ffmpeg)]

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?

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