[FFmpeg-user] v360 expressions

Michael Koch astroelectronic at t-online.de
Thu Feb 27 01:06:45 EET 2020

Am 25.02.2020 um 11:37 schrieb Paul B Mahol:
> On 2/25/20, Paul B Mahol <onemda at gmail.com> wrote:
>> On 2/25/20, Michael Koch <astroelectronic at t-online.de> wrote:
>>> Am 25.02.2020 um 10:40 schrieb Paul B Mahol:
>>>> On 2/25/20, Michael Koch <astroelectronic at t-online.de> wrote:
>>>>> Paul,
>>>>>> On 2/19/20, Michael Koch <astroelectronic at t-online.de> wrote:
>>>>>>> Hi,
>>>>>>> would it be possible to allow expressions for the yaw, pitch and roll
>>>>>>> parameters in the v360 filter? I have a project where I need these
>>>>>>> angles to be a function of time.
>>>>>> Nope, would make filter 10x times slower.
>>>>> Would it always slow down the filter, or only if these expressions are
>>>>> actually a function of time?
>>>>> Some nice effects would be possible when the angles and/or field of
>>>>> view
>>>>> could be functions of time.
>>>>> A "eval" option (like in "eq" filter) could be added to specify when to
>>>>> evaluate the expressions, and the default would be "init" for fast
>>>>> processing.
>>>> Eval is evil. It is not gonna be added.
>>> And what about sendcmd / commands?
>> Will look into adding it.
> Done.

I have tested it and it works to send constant values to the v360 
filter, but it doesn't work to send an expression, as in the 3rd line of 
this *.cmd file. With overlay filter this method works fine.

0.00-1.00 v360 yaw 0;
1.00-2.00 v360 yaw 60;
2.00-4.00 v360 yaw 'lerp(60,120,t-2)';

I understand it doesn't work because v360 doesn't accept expressions.
Would it be possible to evaluate the expression already in sendcmd, and 
then send the result to the target filter?

A workaround would be to write many lines in the *.cmd file, one line 
for each frame.


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