Created attachment 147865 [details] Videoproject file used for performing tests. Alpha channel missing in rendering, black pixels instead *** Different behaviour in comparison to former version, here: 20.08.3. STEPS TO REPRODUCE Creating a simple short video with transparent alpha sections (file attached) 1. Put colour clip into project bin 2. Insert that clip in video track 2. 2. Add transform effect to that clip 3. Shrink clip to size 50% Rendering "with alpha": 4. Render: Choose format: All formats "Video with alpha" tested. OBSERVED RESULT Works fine with version 20.08.3b (with formats VP8, VP9, MOV and custom prores (f=mov acodec=pcm_s16le vcodec=prores_ks vprofile=4444 vendor=ap10 pix_fmt=yuva444p10le mlt_image_format=rgb24a qscale=%quality): Results with 21.12.3 uniformly no alpha, just black pixels in the available formats VP9, MOV, Ut; and in custom prores. VP8 Crashes: "[libvpx @ 0x7fe6e0003740] Transparency encoding with auto_alt_ref does not work Failed to copy encoder parameters to output video stream" (adding auto-alt-ref=0 in the options prevents rendering from crashing but with same result as other formats - no alpha) SOFTWARE/OS VERSIONS Ubuntu 20.04.4 KDE Frameworks Version: 5.68.0 Qt Version: 5.12.8 MLT version 7.4.0 Difference to 20.08.3 where it works still properly: MLT-Version there is 6.23.0 (KDE Frameworks 5.74.0 and Qt 5.14.1 shouldn't be relevant).
Can you please test the latest version and see if you can still reproduce?
(In reply to farid from comment #1) > Can you please test the latest version and see if you can still reproduce? In the version 22.08.0 (linux appimage) "Alpha MOV" works properly "Alpha VP8" crashes as before ("[libvpx @ 0x7fe824002180] Transparency encoding with auto_alt_ref does not work") adding auto-alt-ref=0 in the options -> works fine. "Alpha VP9" works properly "Ut Video" works properly my formerly working custom settings "prores/alpha" (f=mov acodec=pcm_s16le vcodec=prores_ks vprofile=4444 vendor=ap10 pix_fmt=yuva444p10le mlt_image_format=rgb24a qscale=%quality) does NOT (black pixels instead of transparent), even not by changing pix_fmt to yuva420p and mlt_image_format to rgba. The last nightly build "kdenlive-master-325-linux-64-gcc" / Kdenlive_Nightly_appimage-centos7 #325 (Version 22.11.70 (rev. 5cbc6403d)) behaves identically. So maybe it's only the preset for "Alpha V8" that had to be changed. (If the issue is reproducible in other systems). I would be thankful to any hint that could explain why my custom preset still not works.
Created attachment 151709 [details] Alpha VP8_Crashlog I can confirm the crash rendering with Alpha VP8. Attached the crash-log.
I confirm that vp8 is not working and results in crash: Rendering of /tmp/untitled.webm crashed (process:16421): GLib-GObject-WARNING **: 16:08:47.992: cannot register existing type 'gtkmm__GBinding' [libvpx @ 0x7f6ed4201f00] Transparency encoding with auto_alt_ref does not work
I just fixed vp8 alpha encoding by adding the auto-alt-ref=0 parameter to the default render profile. Thanks for your report. https://invent.kde.org/multimedia/kdenlive/-/commit/8a655527e89a364fb0cd283172afac26ccc8c32f Made a few tests but unfortunately I wasn't able to create ProRes videos with alpha either...
Now rendering a PNG with alpha works with Alpha VP8.
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This bug has been in NEEDSINFO status with no change for at least 30 days. The bug is now closed as RESOLVED > WORKSFORME due to lack of needed information. For more information about our bug triaging procedures please read the wiki located here: https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging Thank you for helping us make KDE software even better for everyone!