[FFmpeg-user] ffmpeg architecture question

Michael Koch astroelectronic at t-online.de
Tue Apr 21 12:00:59 EEST 2020

>> 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


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