[FFmpeg-user] ffmpeg architecture question

[Michael Koch]

Am 21.04.2020 um 11:07 schrieb Paul B Mahol:
> On 4/21/20, Michael Koch <astroelectronic at t-online.de> wrote:
>>>> I now appreciate that 'blend' has a "preferred" input similar to
>>>> 'overlay',
>>>> but that behavior is not
>>>> documented. In the case of 'overlay', the name "main" doesn't convey that
>>>> meaning, and in the case
>>>> of 'blend', that behavior is not documented at all. Both documentations
>>>> should explain how
>>>> timestamps control output and that the 1st filter-input's timestamp
>>>> determines the filter-output's
>>>> timestamp.
>>> Blend filter does not have preferred input since long time.
>> If the blend filter gets two input frames with different timestamps,
>> then what's the timestamp of the output frame?
>> I can think ot at least 5 possible scenarios:
>> -- timestamp is copied from the first input
>> -- copied from the second input
>> -- the smaller of the two timestamps
>> -- the larger of the two timestams
>> -- the artihmetic mean of the two timestamps
>>
> It is discouraged to use blend in such case.

How would you solve the problem?
Given is a sequence of frames 1, 2, 3, 4, ...
Wanted is a sequence 1, 1, 1+2, 2, 2, 3, 3, 3+4, 4, 4, ...
where "+" stands for a mix of two frames.

Michael