[FFmpeg-user] multiple flat videos in a equirectangular projection - v360 filter

[Jim Hollingsworth]

SPAM

On Sun, Jul 17, 2022 at 7:54 AM Michael Koch <astroelectronic at t-online.de>
wrote:

> Am 17.07.2022 um 12:09 schrieb Denis Połeć:
> >
> >> Am 16.07.2022 um 22:12 schrieb Michael Koch <
> astroelectronic at t-online.de>:
> >>
> >> Am 16.07.2022 um 20:57 schrieb Denis Połeć:
> >>>> Am 16.07.2022 um 11:46 schrieb Paul B Mahol <onemda at gmail.com>:
> >>>>
> >>>> On Sat, Jul 16, 2022 at 11:22 AM Denis Połeć <denis.polec at gmail.com>
> 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.
> >>
> > Thank you for your reply.
> >
> >> ffmpeg -f lavfi -i color=color=white:size=1920x1080 -lavfi
> drawbox=color=gray:t=1 -frames 1 -y mask.png
> > This works.
> >
> >> ffmpeg -f lavfi -i testsrc2=size=1920x1080 -i mask.png -lavfi
> multiply=offset=0 -frames 1 -y test.png
> > But ffmpeg says multiply filter doesn’t exist.
>
> Get a newer version. The multiply filter was added not so long ago.
>
> Michael
>
> _______________________________________________
> ffmpeg-user mailing list
> ffmpeg-user at ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-user
>
> To unsubscribe, visit link above, or email
> ffmpeg-user-request at ffmpeg.org with subject "unsubscribe".
>