Am 16.07.2022 um 20:57 schrieb Denis Połeć:
Am 16.07.2022 um 11:46 schrieb Paul B Mahol <[email protected]>:
On Sat, Jul 16, 2022 at 11:22 AM Denis Połeć <[email protected]> wrote:
Hello,
I wouldn't call myself a beginner, but I still need a little bit to become
a pro. :)
I have a question that might be easy to answer.
I am working on a script to bring multiple flat videos into a
equirectangular projection by using v360 filter.
I have the problem that the edges of the input are very jagged.
This did not lead to a good result when I play the equirectangular
projection in a 360 player. I have also already tried different
interpolation modes, which does not lead to a better result.
Does anyone have an idea how I can avoid that? Is there a better way to do
this task?
Here is an example code with the result. The video in the example has a
resolution of 1080p:
ffmpeg -i BRAIN.mp4 -lavfi "\
[0]v360=input=flat:output=e:id_fov=45:w=5120:h=2560:yaw='0':alpha_mask=1[fg1];\
[0]v360=input=flat:output=e:id_fov=45:w=5120:h=2560:yaw=90:alpha_mask=1[fg2];[fg2][fg1]overlay[a];\
[0]v360=input=flat:output=e:id_fov=45:w=5120:h=2560:yaw=-90:alpha_mask=1[fg3];[fg3][a]overlay[b];\
[0]v360=input=flat:output=e:id_fov=45:w=5120:h=2560:yaw=180:alpha_mask=1[fg4];[fg4][b]overlay[c];\
\
[0]v360=input=flat:output=e:id_fov=45:w=5120:h=2560:yaw=0:pitch=45:alpha_mask=1[fg5];[fg5][c]overlay[d];\
[0]v360=input=flat:output=e:id_fov=45:w=5120:h=2560:yaw=90:roll=45:alpha_mask=1[fg6];[fg6][d]overlay[e];\
[0]v360=input=flat:output=e:id_fov=45:w=5120:h=2560:yaw=-90:roll=-45:alpha_mask=1[fg7];[fg7][e]overlay[f];\
[0]v360=input=flat:output=e:id_fov=45:w=5120:h=2560:yaw=180:pitch=-45:alpha_mask=1[fg8];[fg8][f]overlay[g];\
\
[0]v360=input=flat:output=e:id_fov=45:w=5120:h=2560:yaw=0:pitch=-45:alpha_mask=1[fg9];[fg9][g]overlay[h];\
[0]v360=input=flat:output=e:id_fov=45:w=5120:h=2560:yaw=90:roll=-45:alpha_mask=1[fg10];[fg10][h]overlay[i];\
[0]v360=input=flat:output=e:id_fov=45:w=5120:h=2560:yaw=-90:roll=45:alpha_mask=1[fg11];[fg11][i]overlay[j];\
[0]v360=input=flat:output=e:id_fov=45:w=5120:h=2560:yaw=180:pitch=45:alpha_mask=1[fg12];[fg12][j]overlay[k];\
\
[0]v360=input=flat:output=e:id_fov=45:w=5120:h=2560:yaw=0:pitch=90:alpha_mask=1[fg13];[fg13][k]overlay[l];\
[0]drawbox=w=1:h=1:color=black,v360=input=flat:output=e:id_fov=45:w=5120:h=2560:yaw=0:pitch=-90:alpha_mask=1[fg14];[fg14][l]overlay"
-q:v 4 -vframes 1 -y test11.jpg
Your filtergraph is extremely inefficient with that many cascaded overlays
and gives poor results. For proper stitching borders need to have small
transition from full opacity to no opacity.
To add small transitions with opacity on borders could use blurring filters
for example on alpha plane only.
How could I achieve that? How can I blurry just the borders?
You could apply some preprocessing to your input video, before you feed
it to your script.
The trick is to multiply all pixels at the edges by 0.5. This can be
done with a white mask which has gray pixels at the edge.
ffmpeg -f lavfi -i color=color=white:size=1920x1080 -lavfi
drawbox=color=gray:t=1 -frames 1 -y mask.png
ffmpeg -f lavfi -i testsrc2=size=1920x1080 -i mask.png -lavfi
multiply=offset=0 -frames 1 -y test.png
Then use test.png as input for your script.
Michael
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