[FFmpeg-user] Pan and scan

[Lingjiang Fang]

On Wed, 16 Dec 2020 18:25:59 +0100
Michael Koch <astroelectronic at t-online.de> wrote:

>Am 16.12.2020 um 17:34 schrieb adam smith via ffmpeg-user:
>> Hi guys,
>>
>> I am looking at turning 16x9 content into 1x1
>> I want to be able to specify the source area that should be used for
>> the output in 1 second increments and move between them smoothly.
>>
>> It looks like I could perhaps use the crop filter or the zoompan
>> filter to achieve this. Does anyone have any reasons why one would
>> be better than the other?
>
>I think in this case it's better to use the crop filter, because it 
>supports commands.
>
>ffmpeg -i in.mp4 -lavfi sendcmd=f=coord.cmd,crop at 1=w=800:h=800:x=0:y=0 
>out.mp4
>
>You can specify the top left coordinates of the square window in the 
>file "coord.cmd":
>
>0.0-1.0 [expr] crop at 1 x 'lerp(0,100,TI)';
>0.0-1.0 [expr] crop at 1 y 'lerp(0,100,TI)';
>1.0-2.0 [expr] crop at 1 x 'lerp(100,150,TI)';
>1.0-2.0 [expr] crop at 1 y 'lerp(100,220,TI)';
>2.0-3.0 [expr] crop at 1 x 'lerp(150,80,TI)';
>2.0-3.0 [expr] crop at 1 y 'lerp(220,220,TI)';
>and so on...
>
>In this example linear interpolation is used in the intervals.
>For more info about 'sendcmd' see also chapter 2.80 in my book:
>http://www.astro-electronic.de/FFmpeg_Book.pdf

wow, the book is a great work, awesome!!!

>
>Michael
>
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--
Best regards,
Lingjiang Fang