Track Matte stinger doesn't work

[madrigal]

Hi all,

I tried to make a Track Matte stinger by generating left and right videos in kdenlive, then conjoining them with ffmpeg. However, whatever I tried with ffmpeg, it didn't work. The ffmpeg command I used was ffmpeg -i "%left%" -i "%right%" -filter_complex hstack -vcodec vp8 "%output%" ( batch file is included). It seems to me the the transparency goes away using ffmpeg, but I don't know why. The command is the same as https://obsproject.com/kb/track-matte-stinger-transitions. (I though it might be a bug in OBS not accepting VP9 or something, but that's not likely either.) Could anyone help me?

obviously, the video-files are only designed in order to troubleshoot, and not what I would use for the stinger.
versions: obs is 30.0.2 and ffmpeg is ffmpeg-2023-12-18-git-be8a4f80b9-full_build

Thanks,
Madrigal

 

[madrigal]

I thought I had searched the internet thoroughly before posting, but apparently the internet is a vast space :-) :whistle:
I found this reddit and it suggested an alternative command, which worked. Because OBS gave a different command, which did not work for me, could that page mention the line of code below (and maybe props to the reddit user)
VP8 input:

ffmpeg -c:v libvpx -i left.webm -c:v libvpx -i left.webm -filter_complex "[0:V:0][1:V:0]hstack,format=yuva420p[out]" -map "[out]" -map 0:a? -map 1:a? -c:v libvpx-vp9 -c:a copy stinger-matte.webm

VP9 input:

ffmpeg -c:v libvpx-vp9 -i left.webm -c:v libvpx-vp9 -i right.webm -filter_complex "[0:V:0][1:V:0]hstack,format=yuva420p[out]" -map "[out]" -map 0:a? -map 1:a? -c:v libvpx-vp9 -c:a copy stinger-matte.webm

glad I found a solution, though I still wonder why it didn't work for me

Cheers, Madrigal