FFmpeg: How to add shadow overlay at the bottom of the video?

Question

I need to add a little shadow at the bottom of the video.

Initial video

Expected result

The one version for doing this is to have the shadow (.png) image which will be added to the video as an overlay. But I thought, is there any way to do it without a shadow image?

llogan · Accepted Answer · 2019-12-18T19:12:58.183

4

Using the split, format, geq, and overlay filters:

ffmpeg -i input.jpg -filter_complex "[0]split[v0][v1];[v0]format=rgba,geq=r=0:g=0:b=0:a=255*(Y/H)[fg];[v1][fg]overlay=format=auto" -frames:v 1 -q:v 2 out.jpg

split - make two copies of the input: one for geq and the other for overlay
format - make the input have alpha channel
geq - create a gradient with alpha
overlay - place gradient over original image

Another example but this adds the crop filter to halve the gradient so it stops in the middle:

ffmpeg -i input.jpg -filter_complex "[0]split[v0][v1];[v0]crop=iw:ih/2,format=rgba,geq=r=0:g=0:b=0:a=255*(Y/H)[fg];[v1][fg]overlay=0:H-h:format=auto" -frames:v 1 -q:v 2 out.jpg

There is probably a more efficient way to do this, but it works. See filter documentation.

edited Dec 18 '19 at 19:12

answered Dec 17 '19 at 19:31

llogan

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What would we change if we wanted the overlay at a different position on the video and not the bottom? Could you please elaborate on that bit? – Navid Khan Feb 27 '20 at 09:51
@NavedKhan Which position? – llogan Feb 27 '20 at 18:17
For instance, if I wanted the same overlay at the top of the video. ( The overlay would have to be inversed as well ) – Navid Khan Feb 28 '20 at 05:01
I've came up with this solution to add the gradient-angle: https://gist.github.com/coderofsalvation/bb922e8e9cfed101ad4e9e1700d9ef25 – coderofsalvation Nov 09 '20 at 08:52
@llogan is it possible to add shadow or shadow image outside(like actual shadow means behind) of the video not an overlay?? – Vivek Thummar Mar 18 '21 at 07:13
@VivekThummar A drop shadow? You should ask a new question since it would be a completely different method. – llogan Mar 18 '21 at 18:24
ok, i will ask a new question in next some days(sorry for that).. – Vivek Thummar Mar 19 '21 at 04:48

FFmpeg: How to add shadow overlay at the bottom of the video?

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