On Mon, May 18, 2026 at 12:03 PM Andrea paz <gamberucci.andrea@gmail.com> wrote:
I'm not sure how the x265 patches with an alpha channel work.
well, I placed usual jpeg file on second (bottom) track relative to track with transparent video file. as long as jpeg file is bigger than image it should show up in compositor behind figures ... rendering prores with alpha file alone into x265 + alpha should give you file behaving like original prores + alpha and non-transparent jpeg. order (who is on top track) matters!
For my tests, I used an H.264 background without transparency (aereo.mp4). On top of that, I placed the four “puppet” files I downloaded from the Apple website Andrew mentioned. Here's the link to download the files.
https://developer.apple.com/documentation/avfoundation/using-hevc-video-with...
Or, to save time, here’s the link to my Dropbox folder where I’ve gathered the four files plus the render file:
https://www.dropbox.com/scl/fi/ovavq5cqmtfvosz7ulhoy/Archivio.tar.gz?rlkey=5...
Test:
- puppets_with_alpha_hevc.mov It does not display transparency on the timeline or in the rendering created with the "h265_alpha.mp4" preset. - puppets_with_alpha_prores-60fps.mp4 It does not display transparency on the timeline or in the rendering created with the h265_alpha.mp4 preset. - puppets_with_alpha_prores.mov shows transparency on the timeline and in the final render - puppets_with_greenbg_hevc.mov Shows the transparency on the timeline and in the final render after removing the green background using chroma key.
Other files with transparency don't work in either decoding or encoding.
Given these results, I can't figure out what makes transparency work and what doesn't. Codecs? Formats? My system? NOTE: I tried the Kdenlive AppImage and got the same results.
Here's a link to a video showing my tests:
https://www.dropbox.com/scl/fi/lspehro82yvyqozdygq77/2026-05-18_10-22-41.mkv...