I get a box in the bottom corner showing "Preview rendering failed, check your parameters": https://i.imgur.com/2SSMnOz.png The error is "Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codepar instead." https://i.imgur.com/MDYn5kr.png This happens "out of the box" with the default configuration on Debian Testing for me. This is a warning and not an error, and shouldn't be reported as an error. The X also needs to be pressed dozens of times to clear the repeated warning - it should clear all of the same warning at once.
This warning shows you that there is no accurate preview rendering settings available. You have to copy an existing pre rendering setting and adjust it to your actual project/clip size and type.
Dear Bug Submitter, This bug has been in NEEDSINFO status with no change for at least 15 days. Please provide the requested information as soon as possible and set the bug status as REPORTED. Due to regular bug tracker maintenance, if the bug is still in NEEDSINFO status with no change in 30 days the bug will be 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 If you have already provided the requested information, please mark the bug as REPORTED so that the KDE team knows that the bug is ready to be confirmed. Thank you for helping us make KDE software even better for everyone!
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!