[FFmpeg-user] v360 expressions

Paul B Mahol onemda at gmail.com
Thu Feb 27 01:14:23 EET 2020

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).

More information about the ffmpeg-user mailing list