[FFmpeg-user] v360 expressions

Paul B Mahol onemda at gmail.com
Thu Feb 27 12:25:43 EET 2020

On 2/27/20, Michael Koch <astroelectronic at t-online.de> wrote:
> Am 27.02.2020 um 00:14 schrieb 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.
> Evil and ugly? That's no problem for me :-)  I need expressions for some
> special effects and don't care about processing speed.
> Regarding "limited" I have the opposite opinion. It's a limitation not
> to have expressions.

And I need money, so free work has to stop.

>> Use mpv player, which have support to send commands via keybindings,
>> you could even write lua plugin(s).
> Thanks for these hints, will have a look at them.
> Michael
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