[FFmpeg-user] ffmpeg architecture question

[Paul B Mahol]

On 4/21/20, Michael Koch <astroelectronic at t-online.de> wrote:
> 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.
>

Sometimes best solution is no solution.