[FFmpeg-user] v360 expressions

[Paul B Mahol]

On 2/27/20, Michael Koch <astroelectronic at t-online.de> wrote:
> 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.

I told you already that expressions are evil, slow, limited and ugly.
Use mpv player, which have support to send commands via keybindings,
you could even write lua plugin(s).